diff --git a/src/Core/OAuth1Provider.php b/src/Core/OAuth1Provider.php
index 6b2e5489..9821f6dd 100644
--- a/src/Core/OAuth1Provider.php
+++ b/src/Core/OAuth1Provider.php
@@ -60,7 +60,7 @@ public function getRequestToken():AccessToken{
 			->withHeader('Content-Length', '0') // tumblr requires a content-length header set
 		;
 
-		foreach($this->authHeaders as $header => $value){
+		foreach($this::HEADERS_AUTH as $header => $value){
 			$request = $request->withAddedHeader($header, $value);
 		}
 
diff --git a/src/Core/OAuth2Interface.php b/src/Core/OAuth2Interface.php
index 79b039da..9fa58763 100644
--- a/src/Core/OAuth2Interface.php
+++ b/src/Core/OAuth2Interface.php
@@ -18,9 +18,49 @@
  */
 interface OAuth2Interface extends OAuthInterface{
 
+	/** @var int */
 	public const AUTH_METHOD_HEADER = 1;
+	/** @var int */
 	public const AUTH_METHOD_QUERY  = 2;
 
+	/**
+	 * Specifies the authentication method:
+	 *
+	 *   - OAuth2Interface::AUTH_METHOD_HEADER (Bearer, OAuth, ...)
+	 *   - OAuth2Interface::AUTH_METHOD_QUERY (access_token, ...)
+	 *
+	 * @var int
+	 */
+	public const AUTH_METHOD = self::AUTH_METHOD_HEADER;
+
+	/**
+	 * The name of the authentication header in case of OAuth2Interface::AUTH_METHOD_HEADER
+	 *
+	 * @var string
+	 */
+	public const AUTH_PREFIX_HEADER = 'Bearer';
+
+	/**
+	 * The name of the authentication query parameter in case of OAuth2Interface::AUTH_METHOD_QUERY
+	 *
+	 * @var string
+	 */
+	public const AUTH_PREFIX_QUERY = 'access_token';
+
+	/**
+	 * Default scopes to apply if none were provided via the $scopes parameter
+	 *
+	 * @var string[]
+	 */
+	public const DEFAULT_SCOPES = [];
+
+	/**
+	 * The delimiter string for scopes
+	 *
+	 * @var string
+	 */
+	public const SCOPE_DELIMITER = ' ';
+
 	/**
 	 * Obtains an OAuth2 access token with the given $code, verifies the $state
 	 * if the provider implements the CSRFToken interface, and returns an AccessToken object
diff --git a/src/Core/OAuth2Provider.php b/src/Core/OAuth2Provider.php
index f85e2aee..29b1e1f4 100644
--- a/src/Core/OAuth2Provider.php
+++ b/src/Core/OAuth2Provider.php
@@ -25,28 +25,6 @@
  */
 abstract class OAuth2Provider extends OAuthProvider implements OAuth2Interface{
 
-	/**
-	 * Specifies the authentication method:
-	 *   - OAuth2Interface::AUTH_METHOD_HEADER (Bearer, OAuth, ...)
-	 *   - OAuth2Interface::AUTH_METHOD_QUERY (access_token, ...)
-	 */
-	protected int $authMethod = self::AUTH_METHOD_HEADER;
-
-	/**
-	 * The name of the authentication header in case of OAuth2Interface::AUTH_METHOD_HEADER
-	 */
-	protected string $authMethodHeader = 'Bearer';
-
-	/**
-	 * The name of the authentication query parameter in case of OAuth2Interface::AUTH_METHOD_QUERY
-	 */
-	protected string $authMethodQuery = 'access_token';
-
-	/**
-	 * The delimiter string for scopes
-	 */
-	protected string $scopesDelimiter = ' ';
-
 	/**
 	 * An optional refresh token endpoint in case the provider supports TokenRefresh.
 	 * If the provider supports token refresh and $refreshTokenURL is null, $accessTokenURL will be used instead.
@@ -61,17 +39,12 @@ abstract class OAuth2Provider extends OAuthProvider implements OAuth2Interface{
 	 */
 	protected string|null $clientCredentialsTokenURL = null;
 
-	/**
-	 * Default scopes to apply if none were provided via the $scopes parameter in OAuth2Provider::getAuthURL()
-	 */
-	protected array $defaultScopes = [];
-
 	/**
 	 * @inheritDoc
 	 */
 	public function getAuthURL(array|null $params = null, array|null $scopes = null):UriInterface{
 		$params ??= [];
-		$scopes ??= $this->defaultScopes;
+		$scopes ??= $this::DEFAULT_SCOPES;
 
 		unset($params['client_secret']);
 
@@ -83,7 +56,7 @@ public function getAuthURL(array|null $params = null, array|null $scopes = null)
 		]);
 
 		if(!empty($scopes)){
-			$params['scope'] = implode($this->scopesDelimiter, $scopes);
+			$params['scope'] = implode($this::SCOPE_DELIMITER, $scopes);
 		}
 
 		if($this instanceof CSRFToken){
@@ -128,7 +101,7 @@ protected function parseTokenResponse(ResponseInterface $response):AccessToken{
 		if(isset($data['scope']) || isset($data['scopes'])){
 			$scope = ($data['scope'] ?? $data['scopes'] ?? []);
 
-			$token->scopes = (is_array($scope)) ? $scope : explode($this->scopesDelimiter, $scope);
+			$token->scopes = (is_array($scope)) ? $scope : explode($this::SCOPE_DELIMITER, $scope);
 		}
 
 		unset($data['expires_in'], $data['refresh_token'], $data['access_token'], $data['scope'], $data['scopes']);
@@ -161,7 +134,7 @@ public function getAccessToken(string $code, string|null $state = null):AccessTo
 			->withHeader('Accept-Encoding', 'identity')
 			->withBody($this->streamFactory->createStream(QueryUtil::build($body, PHP_QUERY_RFC1738)));
 
-		foreach($this->authHeaders as $header => $value){
+		foreach($this::HEADERS_AUTH as $header => $value){
 			$request = $request->withHeader($header, $value);
 		}
 
@@ -177,17 +150,17 @@ public function getAccessToken(string $code, string|null $state = null):AccessTo
 	 */
 	public function getRequestAuthorization(RequestInterface $request, AccessToken $token):RequestInterface{
 
-		if($this->authMethod === OAuth2Interface::AUTH_METHOD_HEADER){
-			return $request->withHeader('Authorization', $this->authMethodHeader.' '.$token->accessToken);
+		if($this::AUTH_METHOD === OAuth2Interface::AUTH_METHOD_HEADER){
+			return $request->withHeader('Authorization', $this::AUTH_PREFIX_HEADER.' '.$token->accessToken);
 		}
 
-		if($this->authMethod === OAuth2Interface::AUTH_METHOD_QUERY){
-			$uri = QueryUtil::merge((string)$request->getUri(), [$this->authMethodQuery => $token->accessToken]);
+		if($this::AUTH_METHOD === OAuth2Interface::AUTH_METHOD_QUERY){
+			$uri = QueryUtil::merge((string)$request->getUri(), [$this::AUTH_PREFIX_QUERY => $token->accessToken]);
 
 			return $request->withUri($this->uriFactory->createUri($uri));
 		}
 
-		throw new ProviderException('invalid auth type');
+		throw new ProviderException('invalid auth AUTH_METHOD');
 	}
 
 	/**
@@ -203,7 +176,7 @@ public function getClientCredentialsToken(array|null $scopes = null):AccessToken
 		$params = ['grant_type' => 'client_credentials'];
 
 		if(!empty($scopes)){
-			$params['scope'] = implode($this->scopesDelimiter, $scopes);
+			$params['scope'] = implode($this::SCOPE_DELIMITER, $scopes);
 		}
 
 		$request = $this->requestFactory
@@ -214,7 +187,7 @@ public function getClientCredentialsToken(array|null $scopes = null):AccessToken
 			->withBody($this->streamFactory->createStream(QueryUtil::build($params, PHP_QUERY_RFC1738)))
 		;
 
-		foreach($this->authHeaders as $header => $value){
+		foreach($this::HEADERS_AUTH as $header => $value){
 			$request = $request->withAddedHeader($header, $value);
 		}
 
@@ -267,7 +240,7 @@ public function refreshAccessToken(AccessToken|null $token = null):AccessToken{
 			->withBody($this->streamFactory->createStream(QueryUtil::build($body, PHP_QUERY_RFC1738)))
 		;
 
-		foreach($this->authHeaders as $header => $value){
+		foreach($this::HEADERS_AUTH as $header => $value){
 			$request = $request->withAddedHeader($header, $value);
 		}
 
diff --git a/src/Core/OAuthInterface.php b/src/Core/OAuthInterface.php
index e8f7a57b..f8909e05 100644
--- a/src/Core/OAuthInterface.php
+++ b/src/Core/OAuthInterface.php
@@ -30,6 +30,20 @@
  */
 interface OAuthInterface extends ClientInterface{
 
+	/**
+	 * additional headers to use during authentication
+	 *
+	 * @var array
+	 */
+	public const HEADERS_AUTH = [];
+
+	/**
+	 * additional headers to use during API access
+	 *
+	 * @var array
+	 */
+	public const HEADERS_API = [];
+
 	/**
 	 * Prepares the URL with optional $params which redirects to the provider's authorization prompt
 	 * and returns a PSR-7 UriInterface with all necessary parameters set
diff --git a/src/Core/OAuthProvider.php b/src/Core/OAuthProvider.php
index 896380f1..5dc4862d 100644
--- a/src/Core/OAuthProvider.php
+++ b/src/Core/OAuthProvider.php
@@ -49,16 +49,6 @@ abstract class OAuthProvider implements OAuthInterface{
 	 */
 	protected string $accessTokenURL;
 
-	/**
-	 * additional headers to use during authentication
-	 */
-	protected array $authHeaders = [];
-
-	/**
-	 * additional headers to use during API access
-	 */
-	protected array $apiHeaders = [];
-
 	/*
 	 * magic properties (public readonly would be cool if the implementation wasn't fucking stupid)
 	 */
@@ -249,7 +239,8 @@ public function request(
 	 * Prepare request headers
 	 */
 	protected function getRequestHeaders(array|null $headers = null):array{
-		return array_merge($this->apiHeaders, ($headers ?? []));
+		/** @noinspection PhpParamsInspection sup PHPStorm?? */
+		return array_merge($this::HEADERS_API, ($headers ?? []));
 	}
 
 	/**
diff --git a/src/Providers/Amazon.php b/src/Providers/Amazon.php
index b4f06403..c0f056ae 100644
--- a/src/Providers/Amazon.php
+++ b/src/Providers/Amazon.php
@@ -29,7 +29,7 @@ class Amazon extends OAuth2Provider implements CSRFToken, TokenRefresh{
 	public const SCOPE_PROFILE_USER_ID = 'profile:user_id';
 	public const SCOPE_POSTAL_CODE     = 'postal_code';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_PROFILE,
 		self::SCOPE_PROFILE_USER_ID,
 	];
diff --git a/src/Providers/BattleNet.php b/src/Providers/BattleNet.php
index f60942de..82e950ed 100644
--- a/src/Providers/BattleNet.php
+++ b/src/Providers/BattleNet.php
@@ -23,12 +23,12 @@
  */
 class BattleNet extends OAuth2Provider implements ClientCredentials, CSRFToken{
 
-	public const SCOPE_OPENID         = 'openid';
-	public const SCOPE_PROFILE_D3     = 'd3.profile';
-	public const SCOPE_PROFILE_SC2    = 'sc2.profile';
-	public const SCOPE_PROFILE_WOW    = 'wow.profile';
+	public const SCOPE_OPENID      = 'openid';
+	public const SCOPE_PROFILE_D3  = 'd3.profile';
+	public const SCOPE_PROFILE_SC2 = 'sc2.profile';
+	public const SCOPE_PROFILE_WOW = 'wow.profile';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_OPENID,
 		self::SCOPE_PROFILE_D3,
 		self::SCOPE_PROFILE_SC2,
diff --git a/src/Providers/BigCartel.php b/src/Providers/BigCartel.php
index 7a1255f4..e669e8e5 100644
--- a/src/Providers/BigCartel.php
+++ b/src/Providers/BigCartel.php
@@ -24,6 +24,10 @@
  */
 class BigCartel extends OAuth2Provider implements CSRFToken, TokenInvalidate{
 
+	public const HEADERS_API = [
+		'Accept' => 'application/vnd.api+json',
+	];
+
 	protected string      $authURL        = 'https://my.bigcartel.com/oauth/authorize';
 	protected string      $accessTokenURL = 'https://api.bigcartel.com/oauth/token';
 	protected string      $revokeURL      = 'https://api.bigcartel.com/oauth/deauthorize/%s'; // sprintf() user id!
@@ -31,7 +35,6 @@ class BigCartel extends OAuth2Provider implements CSRFToken, TokenInvalidate{
 	protected string|null $userRevokeURL  = 'https://my.bigcartel.com/account';
 	protected string|null $apiDocs        = 'https://developers.bigcartel.com/api/v1';
 	protected string|null $applicationURL = 'https://bigcartel.wufoo.com/forms/big-cartel-api-application/';
-	protected array       $apiHeaders     = ['Accept' => 'application/vnd.api+json'];
 
 	/**
 	 * @inheritDoc
diff --git a/src/Providers/Deezer.php b/src/Providers/Deezer.php
index 823ea4fa..d6f14215 100644
--- a/src/Providers/Deezer.php
+++ b/src/Providers/Deezer.php
@@ -24,15 +24,15 @@
  */
 class Deezer extends OAuth2Provider implements CSRFToken{
 
-	public const SCOPE_BASIC              = 'basic_access';
-	public const SCOPE_EMAIL              = 'email';
-	public const SCOPE_OFFLINE_ACCESS     = 'offline_access';
-	public const SCOPE_MANAGE_LIBRARY     = 'manage_library';
-	public const SCOPE_MANAGE_COMMUNITY   = 'manage_community';
-	public const SCOPE_DELETE_LIBRARY     = 'delete_library';
-	public const SCOPE_LISTENING_HISTORY  = 'listening_history';
-
-	protected array $defaultScopes = [
+	public const SCOPE_BASIC             = 'basic_access';
+	public const SCOPE_EMAIL             = 'email';
+	public const SCOPE_OFFLINE_ACCESS    = 'offline_access';
+	public const SCOPE_MANAGE_LIBRARY    = 'manage_library';
+	public const SCOPE_MANAGE_COMMUNITY  = 'manage_community';
+	public const SCOPE_DELETE_LIBRARY    = 'delete_library';
+	public const SCOPE_LISTENING_HISTORY = 'listening_history';
+
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_BASIC,
 		self::SCOPE_EMAIL,
 		self::SCOPE_OFFLINE_ACCESS,
@@ -40,13 +40,14 @@ class Deezer extends OAuth2Provider implements CSRFToken{
 		self::SCOPE_LISTENING_HISTORY,
 	];
 
+	public const AUTH_METHOD = self::AUTH_METHOD_QUERY;
+
 	protected string      $authURL        = 'https://connect.deezer.com/oauth/auth.php';
 	protected string      $accessTokenURL = 'https://connect.deezer.com/oauth/access_token.php';
 	protected string      $apiURL         = 'https://api.deezer.com';
 	protected string|null $userRevokeURL  = 'https://www.deezer.com/account/apps';
 	protected string|null $apiDocs        = 'https://developers.deezer.com/api';
 	protected string|null $applicationURL = 'http://developers.deezer.com/myapps';
-	protected int         $authMethod     = self::AUTH_METHOD_QUERY;
 
 	/**
 	 * @inheritDoc
@@ -61,7 +62,7 @@ public function getAuthURL(array|null $params = null, array|null $scopes = null)
 		$params = array_merge($params, [
 			'app_id'       => $this->options->key,
 			'redirect_uri' => $this->options->callbackURL,
-			'perms'        => implode($this->scopesDelimiter, ($scopes ?? [])),
+			'perms'        => implode($this::SCOPE_DELIMITER, ($scopes ?? [])),
 		]);
 
 		$params = $this->setState($params);
diff --git a/src/Providers/DeviantArt.php b/src/Providers/DeviantArt.php
index 119c3710..a3166433 100644
--- a/src/Providers/DeviantArt.php
+++ b/src/Providers/DeviantArt.php
@@ -21,23 +21,27 @@
  */
 class DeviantArt extends OAuth2Provider implements ClientCredentials, CSRFToken, TokenInvalidate, TokenRefresh{
 
-	public const SCOPE_BASIC              = 'basic';
-	public const SCOPE_BROWSE             = 'browse';
-	public const SCOPE_COLLECTION         = 'collection';
-	public const SCOPE_COMMENT_POST       = 'comment.post';
-	public const SCOPE_FEED               = 'feed';
-	public const SCOPE_GALLERY            = 'gallery';
-	public const SCOPE_MESSAGE            = 'message';
-	public const SCOPE_NOTE               = 'note';
-	public const SCOPE_STASH              = 'stash';
-	public const SCOPE_USER               = 'user';
-	public const SCOPE_USER_MANAGE        = 'user.manage';
-
-	protected array $defaultScopes = [
+	public const SCOPE_BASIC        = 'basic';
+	public const SCOPE_BROWSE       = 'browse';
+	public const SCOPE_COLLECTION   = 'collection';
+	public const SCOPE_COMMENT_POST = 'comment.post';
+	public const SCOPE_FEED         = 'feed';
+	public const SCOPE_GALLERY      = 'gallery';
+	public const SCOPE_MESSAGE      = 'message';
+	public const SCOPE_NOTE         = 'note';
+	public const SCOPE_STASH        = 'stash';
+	public const SCOPE_USER         = 'user';
+	public const SCOPE_USER_MANAGE  = 'user.manage';
+
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_BASIC,
 		self::SCOPE_BROWSE,
 	];
 
+	public const HEADERS_API = [
+		'dA-minor-version' => '20210526',
+	];
+
 	protected string      $authURL        = 'https://www.deviantart.com/oauth2/authorize';
 	protected string      $accessTokenURL = 'https://www.deviantart.com/oauth2/token';
 	protected string      $revokeURL      = 'https://www.deviantart.com/oauth2/revoke';
@@ -45,7 +49,6 @@ class DeviantArt extends OAuth2Provider implements ClientCredentials, CSRFToken,
 	protected string|null $userRevokeURL  = 'https://www.deviantart.com/settings/applications';
 	protected string|null $apiDocs        = 'https://www.deviantart.com/developers/';
 	protected string|null $applicationURL = 'https://www.deviantart.com/developers/apps';
-	protected array       $apiHeaders     = ['dA-minor-version' => '20210526'];
 
 	/**
 	 * @inheritDoc
diff --git a/src/Providers/Discogs.php b/src/Providers/Discogs.php
index 2465c08f..9498a9ff 100644
--- a/src/Providers/Discogs.php
+++ b/src/Providers/Discogs.php
@@ -21,15 +21,17 @@
  */
 class Discogs extends OAuth1Provider{
 
+	public const HEADERS_API = [
+		'Accept' => 'application/vnd.discogs.v2.discogs+json',
+	];
+
 	protected string      $requestTokenURL = 'https://api.discogs.com/oauth/request_token';
 	protected string      $authURL         = 'https://www.discogs.com/oauth/authorize';
 	protected string      $accessTokenURL  = 'https://api.discogs.com/oauth/access_token';
 	protected string      $apiURL          = 'https://api.discogs.com';
 	protected string|null $userRevokeURL   = 'https://www.discogs.com/settings/applications';
 	protected string|null $apiDocs         = 'https://www.discogs.com/developers/';
-	protected string|null $applicationURL  = 'https://www.discogs.com/settings/developers';
-	protected array       $apiHeaders      = ['Accept' => 'application/vnd.discogs.v2.discogs+json'];
-
+	protected string|null $applicationURL = 'https://www.discogs.com/settings/developers';
 	/**
 	 * @inheritDoc
 	 */
diff --git a/src/Providers/Discord.php b/src/Providers/Discord.php
index 504e3180..faa64c9f 100644
--- a/src/Providers/Discord.php
+++ b/src/Providers/Discord.php
@@ -40,7 +40,7 @@ class Discord extends OAuth2Provider implements ClientCredentials, CSRFToken, To
 	public const SCOPE_RPC_NOTIFICATIONS_READ                   = 'rpc.notifications.read';
 	public const SCOPE_WEBHOOK_INCOMING                         = 'webhook.incoming';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_CONNECTIONS,
 		self::SCOPE_EMAIL,
 		self::SCOPE_IDENTIFY,
diff --git a/src/Providers/Foursquare.php b/src/Providers/Foursquare.php
index 2c2ed698..efc49c94 100644
--- a/src/Providers/Foursquare.php
+++ b/src/Providers/Foursquare.php
@@ -21,6 +21,9 @@
  */
 class Foursquare extends OAuth2Provider{
 
+	public const AUTH_METHOD       = self::AUTH_METHOD_QUERY;
+	public const AUTH_PREFIX_QUERY = 'oauth_token';
+
 	protected const API_VERSIONDATE = '20190225';
 
 	protected string      $authURL         = 'https://foursquare.com/oauth2/authenticate';
@@ -29,8 +32,6 @@ class Foursquare extends OAuth2Provider{
 	protected string|null $userRevokeURL   = 'https://foursquare.com/settings/connections';
 	protected string|null $apiDocs         = 'https://developer.foursquare.com/docs';
 	protected string|null $applicationURL  = 'https://foursquare.com/developers/apps';
-	protected string      $authMethodQuery = 'oauth_token';
-	protected int         $authMethod      = self::AUTH_METHOD_QUERY;
 
 	/**
 	 * @inheritDoc
diff --git a/src/Providers/GitHub.php b/src/Providers/GitHub.php
index 4e0fa24f..e130f2f6 100644
--- a/src/Providers/GitHub.php
+++ b/src/Providers/GitHub.php
@@ -47,21 +47,27 @@ class GitHub extends OAuth2Provider implements CSRFToken, TokenRefresh{
 	public const SCOPE_GPG_KEY_WRITE    = 'write:gpg_key';
 	public const SCOPE_GPG_KEY_ADMIN    = 'admin:gpg_key';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_USER,
 		self::SCOPE_USER_EMAIL,
 		self::SCOPE_PUBLIC_REPO,
 		self::SCOPE_GIST,
 	];
 
+	public const HEADERS_AUTH = [
+		'Accept' => 'application/json',
+	];
+
+	public const HEADERS_API = [
+		'Accept' => 'application/vnd.github.beta+json',
+	];
+
 	protected string      $authURL        = 'https://github.com/login/oauth/authorize';
 	protected string      $accessTokenURL = 'https://github.com/login/oauth/access_token';
 	protected string      $apiURL         = 'https://api.github.com';
 	protected string|null $userRevokeURL  = 'https://github.com/settings/applications';
 	protected string|null $apiDocs        = 'https://developer.github.com/';
 	protected string|null $applicationURL = 'https://github.com/settings/developers';
-	protected array       $authHeaders    = ['Accept' => 'application/json'];
-	protected array       $apiHeaders     = ['Accept' => 'application/vnd.github.beta+json'];
 
 	/**
 	 * @inheritDoc
diff --git a/src/Providers/Google.php b/src/Providers/Google.php
index 1d3e4cad..7163e2b5 100644
--- a/src/Providers/Google.php
+++ b/src/Providers/Google.php
@@ -27,7 +27,7 @@ class Google extends OAuth2Provider implements CSRFToken{
 	public const SCOPE_USERINFO_EMAIL   = 'https://www.googleapis.com/auth/userinfo.email';
 	public const SCOPE_USERINFO_PROFILE = 'https://www.googleapis.com/auth/userinfo.profile';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_EMAIL,
 		self::SCOPE_PROFILE,
 	];
diff --git a/src/Providers/GuildWars2.php b/src/Providers/GuildWars2.php
index 6e6ee3b9..777ffb85 100644
--- a/src/Providers/GuildWars2.php
+++ b/src/Providers/GuildWars2.php
@@ -23,18 +23,18 @@
  */
 class GuildWars2 extends OAuth2Provider{
 
-	public const SCOPE_ACCOUNT        = 'account';
-	public const SCOPE_INVENTORIES    = 'inventories';
-	public const SCOPE_CHARACTERS     = 'characters';
-	public const SCOPE_TRADINGPOST    = 'tradingpost';
-	public const SCOPE_WALLET         = 'wallet';
-	public const SCOPE_UNLOCKS        = 'unlocks';
-	public const SCOPE_PVP            = 'pvp';
-	public const SCOPE_BUILDS         = 'builds';
-	public const SCOPE_PROGRESSION    = 'progression';
-	public const SCOPE_GUILDS         = 'guilds';
-
-	protected const AUTH_ERRMSG       = 'GuildWars2 does not support authentication anymore.';
+	public const SCOPE_ACCOUNT     = 'account';
+	public const SCOPE_INVENTORIES = 'inventories';
+	public const SCOPE_CHARACTERS  = 'characters';
+	public const SCOPE_TRADINGPOST = 'tradingpost';
+	public const SCOPE_WALLET      = 'wallet';
+	public const SCOPE_UNLOCKS     = 'unlocks';
+	public const SCOPE_PVP         = 'pvp';
+	public const SCOPE_BUILDS      = 'builds';
+	public const SCOPE_PROGRESSION = 'progression';
+	public const SCOPE_GUILDS      = 'guilds';
+
+	protected const AUTH_ERRMSG = 'GuildWars2 does not support authentication anymore.';
 
 	protected string      $authURL        = 'https://api.guildwars2.com/v2/tokeninfo';
 	protected string      $apiURL         = 'https://api.guildwars2.com';
@@ -71,7 +71,7 @@ public function storeGW2Token(string $access_token):AccessToken{
 				'token_type' => 'Bearer',
 				'id'         => $tokeninfo->id,
 				'name'       => $tokeninfo->name,
-				'scope'      => implode($this->scopesDelimiter, $tokeninfo->permissions),
+				'scope'      => implode($this::SCOPE_DELIMITER, $tokeninfo->permissions),
 			];
 
 			$this->storage->storeAccessToken($token, $this->serviceName);
diff --git a/src/Providers/LastFM.php b/src/Providers/LastFM.php
index 3683265e..eea2e60c 100644
--- a/src/Providers/LastFM.php
+++ b/src/Providers/LastFM.php
@@ -28,7 +28,8 @@ class LastFM extends OAuthProvider{
 	public const PERIOD_3MONTH  = '3month';
 	public const PERIOD_6MONTH  = '6month';
 	public const PERIOD_12MONTH = '12month';
-	public const PERIODS        = [
+
+	public const PERIODS = [
 		self::PERIOD_OVERALL,
 		self::PERIOD_7DAY,
 		self::PERIOD_1MONTH,
@@ -169,7 +170,7 @@ public function request(
 		/** @phan-suppress-next-line PhanTypeMismatchArgumentNullable */
 		$request = $this->requestFactory->createRequest($method, QueryUtil::merge($this->apiURL, $params));
 
-		foreach(array_merge($this->apiHeaders, ($headers ?? [])) as $header => $value){
+		foreach(array_merge($this::HEADERS_API, ($headers ?? [])) as $header => $value){
 			$request = $request->withAddedHeader($header, $value);
 		}
 
diff --git a/src/Providers/MailChimp.php b/src/Providers/MailChimp.php
index 1908f165..bd7f7bab 100644
--- a/src/Providers/MailChimp.php
+++ b/src/Providers/MailChimp.php
@@ -22,14 +22,13 @@
  */
 class MailChimp extends OAuth2Provider implements CSRFToken{
 
-	protected const API_BASE            = 'https://%s.api.mailchimp.com';
-	protected const METADATA_ENDPOINT   = 'https://login.mailchimp.com/oauth2/metadata';
-
-	protected string      $authURL          = 'https://login.mailchimp.com/oauth2/authorize';
-	protected string      $accessTokenURL   = 'https://login.mailchimp.com/oauth2/token';
-	protected string|null $apiDocs          = 'https://developer.mailchimp.com/';
-	protected string|null $applicationURL   = 'https://admin.mailchimp.com/account/oauth2/';
-	protected string      $authMethodHeader = 'OAuth';
+	protected const API_BASE          = 'https://%s.api.mailchimp.com';
+	protected const METADATA_ENDPOINT = 'https://login.mailchimp.com/oauth2/metadata';
+
+	protected string      $authURL        = 'https://login.mailchimp.com/oauth2/authorize';
+	protected string      $accessTokenURL = 'https://login.mailchimp.com/oauth2/token';
+	protected string|null $apiDocs        = 'https://developer.mailchimp.com/';
+	protected string|null $applicationURL = 'https://admin.mailchimp.com/account/oauth2/';
 
 	/**
 	 * @throws \chillerlan\OAuth\OAuthException
diff --git a/src/Providers/Mastodon.php b/src/Providers/Mastodon.php
index e01ddabd..9978ad64 100644
--- a/src/Providers/Mastodon.php
+++ b/src/Providers/Mastodon.php
@@ -28,14 +28,13 @@ class Mastodon extends OAuth2Provider implements CSRFToken, TokenRefresh{
 	public const SCOPE_FOLLOW = 'follow';
 	public const SCOPE_PUSH   = 'push';
 
-	protected string|null $apiDocs = 'https://docs.joinmastodon.org/api/';
-
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_READ,
 		self::SCOPE_FOLLOW,
 	];
 
-	protected string $instance = '';
+	protected string|null $apiDocs  = 'https://docs.joinmastodon.org/api/';
+	protected string      $instance = '';
 
 	/**
 	 * set the internal URLs for the given Mastodon instance
diff --git a/src/Providers/MicrosoftGraph.php b/src/Providers/MicrosoftGraph.php
index fb58d334..3860fca9 100644
--- a/src/Providers/MicrosoftGraph.php
+++ b/src/Providers/MicrosoftGraph.php
@@ -22,7 +22,7 @@ class MicrosoftGraph extends AzureActiveDirectory{
 	public const SCOPE_USER_READ          = 'User.Read';
 	public const SCOPE_USER_READBASIC_ALL = 'User.ReadBasic.All';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_OPENID,
 		self::SCOPE_OPENID_EMAIL,
 		self::SCOPE_OPENID_PROFILE,
diff --git a/src/Providers/Mixcloud.php b/src/Providers/Mixcloud.php
index c3f08f70..f246c846 100644
--- a/src/Providers/Mixcloud.php
+++ b/src/Providers/Mixcloud.php
@@ -22,13 +22,14 @@
  */
 class Mixcloud extends OAuth2Provider{
 
+	public const AUTH_METHOD = self::AUTH_METHOD_QUERY;
+
 	protected string      $authURL        = 'https://www.mixcloud.com/oauth/authorize';
 	protected string      $accessTokenURL = 'https://www.mixcloud.com/oauth/access_token';
 	protected string      $apiURL         = 'https://api.mixcloud.com';
 	protected string|null $userRevokeURL  = 'https://www.mixcloud.com/settings/applications/';
 	protected string|null $apiDocs        = 'https://www.mixcloud.com/developers/';
 	protected string|null $applicationURL = 'https://www.mixcloud.com/developers/create/';
-	protected int         $authMethod     = self::AUTH_METHOD_QUERY;
 
 	/**
 	 * @inheritDoc
diff --git a/src/Providers/MusicBrainz.php b/src/Providers/MusicBrainz.php
index 669332d0..e6425326 100644
--- a/src/Providers/MusicBrainz.php
+++ b/src/Providers/MusicBrainz.php
@@ -30,7 +30,7 @@ class MusicBrainz extends OAuth2Provider implements CSRFToken, TokenRefresh{
 	public const SCOPE_SUBMIT_ISRC    = 'submit_isrc';
 	public const SCOPE_SUBMIT_BARCODE = 'submit_barcode';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_PROFILE,
 		self::SCOPE_EMAIL,
 		self::SCOPE_TAG,
diff --git a/src/Providers/NPROne.php b/src/Providers/NPROne.php
index 04717ecd..e192b952 100644
--- a/src/Providers/NPROne.php
+++ b/src/Providers/NPROne.php
@@ -27,7 +27,7 @@ class NPROne extends OAuth2Provider implements CSRFToken, TokenRefresh, TokenInv
 	public const SCOPE_LISTENING_WRITE    = 'listening.write';
 	public const SCOPE_LOCALACTIVATION    = 'localactivation';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_IDENTITY_READONLY,
 		self::SCOPE_LISTENING_READONLY,
 	];
diff --git a/src/Providers/OpenCaching.php b/src/Providers/OpenCaching.php
index ccac33e8..c84b754f 100644
--- a/src/Providers/OpenCaching.php
+++ b/src/Providers/OpenCaching.php
@@ -13,13 +13,19 @@
 use chillerlan\HTTP\Utils\MessageUtil;
 use chillerlan\OAuth\Core\{OAuth1Provider};
 use Psr\Http\Message\ResponseInterface;
-use function sprintf;
+use function implode, sprintf;
 
 /**
  * @see https://www.opencaching.de/okapi/
  */
 class OpenCaching extends OAuth1Provider{
 
+	protected const USER_FIELDS = [
+		'uuid', 'username', 'profile_url', 'internal_id', 'date_registered',
+		'caches_found', 'caches_notfound', 'caches_hidden', 'rcmds_given',
+		'rcmds_left', 'rcmd_founds_needed', 'home_location',
+	];
+
 	protected string      $requestTokenURL = 'https://www.opencaching.de/okapi/services/oauth/request_token';
 	protected string      $authURL         = 'https://www.opencaching.de/okapi/services/oauth/authorize';
 	protected string      $accessTokenURL  = 'https://www.opencaching.de/okapi/services/oauth/access_token';
@@ -32,7 +38,7 @@ class OpenCaching extends OAuth1Provider{
 	 * @inheritDoc
 	 */
 	public function me():ResponseInterface{
-		$response = $this->request('/users/user', ['fields' => 'uuid|username|profile_url|internal_id|date_registered|caches_found|caches_notfound|caches_hidden|rcmds_given|rcmds_left|rcmd_founds_needed|home_location']);
+		$response = $this->request('/users/user', ['fields' => implode('|', $this::USER_FIELDS)]);
 		$status   = $response->getStatusCode();
 
 		if($status === 200){
diff --git a/src/Providers/OpenStreetmap2.php b/src/Providers/OpenStreetmap2.php
index baec444e..c66981d3 100644
--- a/src/Providers/OpenStreetmap2.php
+++ b/src/Providers/OpenStreetmap2.php
@@ -36,7 +36,7 @@ class OpenStreetmap2 extends OAuth2Provider implements CSRFToken{
 	public const SCOPE_WRITE_REDACTIONS = 'write_redactions';
 	public const SCOPE_OPENID           = 'openid';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_READ_GPX,
 		self::SCOPE_READ_PREFS,
 	];
diff --git a/src/Providers/Patreon.php b/src/Providers/Patreon.php
index 1d673bf8..aeca6483 100644
--- a/src/Providers/Patreon.php
+++ b/src/Providers/Patreon.php
@@ -36,7 +36,7 @@ class Patreon extends OAuth2Provider implements CSRFToken, TokenRefresh{
 	public const SCOPE_V2_CAMPAIGNS_MEMBERS_EMAIL   = 'campaigns.members[email]';
 	public const SCOPE_V2_CAMPAIGNS_MEMBERS_ADDRESS = 'campaigns.members.address';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_V2_IDENTITY,
 		self::SCOPE_V2_IDENTITY_EMAIL,
 		self::SCOPE_V2_IDENTITY_MEMBERSHIPS,
diff --git a/src/Providers/PayPal.php b/src/Providers/PayPal.php
index 0cf805c1..3e6a6488 100644
--- a/src/Providers/PayPal.php
+++ b/src/Providers/PayPal.php
@@ -27,7 +27,7 @@ class PayPal extends OAuth2Provider implements ClientCredentials, CSRFToken, Tok
 	public const SCOPE_ADDRESS        = 'address';
 	public const SCOPE_ACCOUNT        = 'https://uri.paypal.com/services/paypalattributes';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_BASIC_AUTH,
 		self::SCOPE_EMAIL,
 	];
@@ -73,7 +73,7 @@ protected function parseTokenResponse(ResponseInterface $response):AccessToken{
 		$token->accessToken  = $data['access_token'];
 		$token->expires      = ($data['expires_in'] ?? AccessToken::EOL_NEVER_EXPIRES);
 		$token->refreshToken = ($data['refresh_token'] ?? null);
-		$token->scopes       = explode($this->scopesDelimiter, ($data['scope'] ?? ''));
+		$token->scopes       = explode($this::SCOPE_DELIMITER, ($data['scope'] ?? ''));
 
 		unset($data['expires_in'], $data['refresh_token'], $data['access_token'], $data['scope']);
 
diff --git a/src/Providers/Slack.php b/src/Providers/Slack.php
index 8e1240b4..f7cf4a4c 100644
--- a/src/Providers/Slack.php
+++ b/src/Providers/Slack.php
@@ -78,7 +78,7 @@ class Slack extends OAuth2Provider implements CSRFToken{
 	public const SCOPE_USERS_READ_EMAIL    = 'users:read.email';
 	public const SCOPE_USERS_WRITE         = 'users:write';
 
-	protected array $defaultScopes         = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_IDENTITY_AVATAR,
 		self::SCOPE_IDENTITY_BASIC,
 		self::SCOPE_IDENTITY_EMAIL,
diff --git a/src/Providers/SoundCloud.php b/src/Providers/SoundCloud.php
index 882ccf24..37edf06c 100644
--- a/src/Providers/SoundCloud.php
+++ b/src/Providers/SoundCloud.php
@@ -25,17 +25,18 @@ class SoundCloud extends OAuth2Provider implements ClientCredentials, TokenRefre
 	public const SCOPE_NONEXPIRING      = 'non-expiring';
 #	public const SCOPE_EMAIL            = 'email'; // ???
 
-	protected array   $defaultScopes    = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_NONEXPIRING,
 	];
 
-	protected string      $authURL          = 'https://api.soundcloud.com/connect';
-	protected string      $accessTokenURL   = 'https://api.soundcloud.com/oauth2/token';
-	protected string      $apiURL           = 'https://api.soundcloud.com';
-	protected string|null $userRevokeURL    = 'https://soundcloud.com/settings/connections';
-	protected string|null $apiDocs          = 'https://developers.soundcloud.com/';
-	protected string|null $applicationURL   = 'https://soundcloud.com/you/apps';
-	protected string      $authMethodHeader = 'OAuth';
+	public const AUTH_PREFIX_HEADER = 'OAuth';
+
+	protected string      $authURL        = 'https://api.soundcloud.com/connect';
+	protected string      $accessTokenURL = 'https://api.soundcloud.com/oauth2/token';
+	protected string      $apiURL         = 'https://api.soundcloud.com';
+	protected string|null $userRevokeURL  = 'https://soundcloud.com/settings/connections';
+	protected string|null $apiDocs        = 'https://developers.soundcloud.com/';
+	protected string|null $applicationURL = 'https://soundcloud.com/you/apps';
 
 	/**
 	 * @inheritDoc
diff --git a/src/Providers/Spotify.php b/src/Providers/Spotify.php
index c0fb4a45..924c8793 100644
--- a/src/Providers/Spotify.php
+++ b/src/Providers/Spotify.php
@@ -59,7 +59,7 @@ class Spotify extends OAuth2Provider implements ClientCredentials, CSRFToken, To
 	public const SCOPE_USER_MANAGE_PARTNER         = 'user-manage-partner';
 	public const SCOPE_USER_CREATE_PARTNER         = 'user-create-partner';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_PLAYLIST_READ_COLLABORATIVE,
 		self::SCOPE_PLAYLIST_MODIFY_PUBLIC,
 		self::SCOPE_USER_FOLLOW_MODIFY,
diff --git a/src/Providers/SteamOpenID.php b/src/Providers/SteamOpenID.php
index f663b967..70d0c56a 100644
--- a/src/Providers/SteamOpenID.php
+++ b/src/Providers/SteamOpenID.php
@@ -29,11 +29,12 @@ class SteamOpenID extends OAuthProvider{
 	protected string|null $apiDocs        = 'https://developer.valvesoftware.com/wiki/Steam_Web_API';
 
 	/**
+	 * we ignore user supplied params here
+	 *
 	 * @inheritDoc
 	 */
 	public function getAuthURL(array|null $params = null):UriInterface{
 
-		// we ignore user supplied params here
 		$params = [
 			'openid.ns'         => 'http://specs.openid.net/auth/2.0',
 			'openid.mode'       => 'checkid_setup',
diff --git a/src/Providers/Stripe.php b/src/Providers/Stripe.php
index 94d373f9..efb2c841 100644
--- a/src/Providers/Stripe.php
+++ b/src/Providers/Stripe.php
@@ -24,10 +24,10 @@
  */
 class Stripe extends OAuth2Provider implements CSRFToken, TokenRefresh, TokenInvalidate{
 
-	public const SCOPE_READ_WRITE     = 'read_write';
-	public const SCOPE_READ_ONLY      = 'read_only';
+	public const SCOPE_READ_WRITE = 'read_write';
+	public const SCOPE_READ_ONLY  = 'read_only';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_READ_ONLY,
 	];
 
diff --git a/src/Providers/Tumblr2.php b/src/Providers/Tumblr2.php
index 1036c2cd..cfaf1a7e 100644
--- a/src/Providers/Tumblr2.php
+++ b/src/Providers/Tumblr2.php
@@ -26,7 +26,7 @@ class Tumblr2 extends OAuth2Provider implements CSRFToken, TokenRefresh{
 	public const SCOPE_WRITE          = 'write';
 	public const SCOPE_OFFLINE_ACCESS = 'offline_access';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_BASIC,
 		self::SCOPE_WRITE,
 		self::SCOPE_OFFLINE_ACCESS,
diff --git a/src/Providers/Twitch.php b/src/Providers/Twitch.php
index 279046cf..1950bdce 100644
--- a/src/Providers/Twitch.php
+++ b/src/Providers/Twitch.php
@@ -45,10 +45,18 @@ class Twitch extends OAuth2Provider implements ClientCredentials, CSRFToken, Tok
 	public const SCOPE_USER_READ_EMAIL            = 'user:read:email';
 	public const SCOPE_USER_READ_SUBSCRIPTIONS    = 'user:read:subscriptions';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_USER_READ_EMAIL,
 	];
 
+	public const HEADERS_AUTH = [
+		'Accept' => 'application/vnd.twitchtv.v5+json',
+	];
+
+	public const HEADERS_API  = [
+		'Accept' => 'application/vnd.twitchtv.v5+json',
+	];
+
 	protected string      $authURL        = 'https://id.twitch.tv/oauth2/authorize';
 	protected string      $accessTokenURL = 'https://id.twitch.tv/oauth2/token';
 	protected string      $revokeURL      = 'https://id.twitch.tv/oauth2/revoke';
@@ -56,8 +64,6 @@ class Twitch extends OAuth2Provider implements ClientCredentials, CSRFToken, Tok
 	protected string|null $userRevokeURL  = 'https://www.twitch.tv/settings/connections';
 	protected string|null $apiDocs        = 'https://dev.twitch.tv/docs/api/reference/';
 	protected string|null $applicationURL = 'https://dev.twitch.tv/console/apps/create';
-	protected array       $authHeaders    = ['Accept' => 'application/vnd.twitchtv.v5+json'];
-	protected array       $apiHeaders     = ['Accept' => 'application/vnd.twitchtv.v5+json'];
 
 	/**
 	 * @see https://dev.twitch.tv/docs/authentication#oauth-client-credentials-flow-app-access-tokens
@@ -71,7 +77,7 @@ public function getClientCredentialsToken(array|null $scopes = null):AccessToken
 		];
 
 		if($scopes !== null){
-			$params['scope'] = implode($this->scopesDelimiter, $scopes);
+			$params['scope'] = implode($this::SCOPE_DELIMITER, $scopes);
 		}
 
 		$request = $this->requestFactory
@@ -80,7 +86,7 @@ public function getClientCredentialsToken(array|null $scopes = null):AccessToken
 			->withBody($this->streamFactory->createStream(QueryUtil::build($params, PHP_QUERY_RFC1738)))
 		;
 
-		foreach($this->authHeaders as $header => $value){
+		foreach($this::HEADERS_AUTH as $header => $value){
 			$request = $request->withAddedHeader($header, $value);
 		}
 
@@ -96,7 +102,7 @@ public function getClientCredentialsToken(array|null $scopes = null):AccessToken
 	 */
 	public function getRequestAuthorization(RequestInterface $request, AccessToken $token):RequestInterface{
 		return $request
-			->withHeader('Authorization', $this->authMethodHeader.' '.$token->accessToken)
+			->withHeader('Authorization', $this::AUTH_PREFIX_HEADER.' '.$token->accessToken)
 			->withHeader('Client-ID', $this->options->key);
 	}
 
diff --git a/src/Providers/Twitter.php b/src/Providers/Twitter.php
index aa579740..9c9f7c7b 100644
--- a/src/Providers/Twitter.php
+++ b/src/Providers/Twitter.php
@@ -25,9 +25,9 @@ class Twitter extends OAuth1Provider{
 
 	// choose your fighter
 	/** @see https://developer.twitter.com/en/docs/basics/authentication/api-reference/authorize */
-	protected string $authURL          = 'https://api.twitter.com/oauth/authorize';
+	protected string $authURL              = 'https://api.twitter.com/oauth/authorize';
 	/** @see https://developer.twitter.com/en/docs/basics/authentication/api-reference/authenticate */
-#	protected string $authURL          = 'https://api.twitter.com/oauth/authenticate';
+#	protected string $authURL              = 'https://api.twitter.com/oauth/authenticate';
 
 	protected string      $requestTokenURL = 'https://api.twitter.com/oauth/request_token';
 	protected string      $accessTokenURL  = 'https://api.twitter.com/oauth/access_token';
diff --git a/src/Providers/TwitterCC.php b/src/Providers/TwitterCC.php
index 957f7cca..426b7e3f 100644
--- a/src/Providers/TwitterCC.php
+++ b/src/Providers/TwitterCC.php
@@ -23,7 +23,7 @@
  */
 class TwitterCC extends OAuth2Provider implements ClientCredentials{
 
-	protected const AUTH_ERRMSG                      = 'TwitterCC only supports Client Credentials Grant, use the Twitter OAuth1 class for authentication instead.';
+	protected const AUTH_ERRMSG = 'TwitterCC only supports Client Credentials Grant, use the Twitter OAuth1 class for authentication instead.';
 
 	protected string      $apiURL                    = 'https://api.twitter.com';
 	protected string|null $clientCredentialsTokenURL = 'https://api.twitter.com/oauth2/token';
diff --git a/src/Providers/Vimeo.php b/src/Providers/Vimeo.php
index efb5d828..a200d865 100644
--- a/src/Providers/Vimeo.php
+++ b/src/Providers/Vimeo.php
@@ -36,16 +36,24 @@ class Vimeo extends OAuth2Provider implements ClientCredentials, CSRFToken, Toke
 	public const SCOPE_PROMO_CODES = 'promo_codes';
 	public const SCOPE_VIDEO_FILES = 'video_files';
 
-	// @see https://developer.vimeo.com/api/changelog
-	protected const API_VERSION    = '3.4';
-
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_PUBLIC,
 		self::SCOPE_PRIVATE,
 		self::SCOPE_INTERACT,
 		self::SCOPE_STATS,
 	];
 
+	// @see https://developer.vimeo.com/api/changelog
+	protected const API_VERSION    = '3.4';
+
+	public const HEADERS_AUTH = [
+		'Accept' => 'application/vnd.vimeo.*+json;version='.self::API_VERSION,
+	];
+
+	public const HEADERS_API  = [
+		'Accept' => 'application/vnd.vimeo.*+json;version='.self::API_VERSION,
+	];
+
 	protected string      $authURL                   = 'https://api.vimeo.com/oauth/authorize';
 	protected string      $accessTokenURL            = 'https://api.vimeo.com/oauth/access_token';
 	protected string      $revokeURL                 = 'https://api.vimeo.com/tokens';
@@ -54,8 +62,6 @@ class Vimeo extends OAuth2Provider implements ClientCredentials, CSRFToken, Toke
 	protected string|null $clientCredentialsTokenURL = 'https://api.vimeo.com/oauth/authorize/client';
 	protected string|null $apiDocs                   = 'https://developer.vimeo.com';
 	protected string|null $applicationURL            = 'https://developer.vimeo.com/apps';
-	protected array       $authHeaders               = ['Accept' => 'application/vnd.vimeo.*+json;version='.self::API_VERSION];
-	protected array       $apiHeaders                = ['Accept' => 'application/vnd.vimeo.*+json;version='.self::API_VERSION];
 
 	/**
 	 * @inheritDoc
diff --git a/src/Providers/WordPress.php b/src/Providers/WordPress.php
index 82b7fbd1..8f6e1aa9 100644
--- a/src/Providers/WordPress.php
+++ b/src/Providers/WordPress.php
@@ -23,7 +23,7 @@ class WordPress extends OAuth2Provider implements CSRFToken{
 	public const SCOPE_AUTH   = 'auth';
 	public const SCOPE_GLOBAL = 'global';
 
-	protected array $defaultScopes = [
+	public const DEFAULT_SCOPES = [
 		self::SCOPE_GLOBAL,
 	];
 
diff --git a/tests/Core/DummyOAuth1Provider.php b/tests/Core/DummyOAuth1Provider.php
index 1be97cb8..a3e2a6e4 100644
--- a/tests/Core/DummyOAuth1Provider.php
+++ b/tests/Core/DummyOAuth1Provider.php
@@ -19,14 +19,15 @@
  */
 final class DummyOAuth1Provider extends OAuth1Provider implements TokenInvalidate{
 
-	protected string  $authURL         = 'https://example.com/oauth/authorize';
-	protected string  $accessTokenURL  = 'https://example.com/oauth/access_token';
-	protected string  $requestTokenURL = 'https://example.com/oauth/request_token';
-	protected string  $revokeURL       = 'https://example.com/oauth/revoke';
-	protected string  $apiURL          = 'https://api.example.com';
-	protected ?string $userRevokeURL   = 'https://account.example.com/apps/';
-	protected array   $authHeaders     = ['foo' => 'bar'];
-	protected array   $apiHeaders      = ['foo' => 'bar'];
+	public const HEADERS_AUTH = ['foo' => 'bar'];
+	public const HEADERS_API  = ['foo' => 'bar'];
+
+	protected string      $authURL         = 'https://example.com/oauth/authorize';
+	protected string      $accessTokenURL  = 'https://example.com/oauth/access_token';
+	protected string      $requestTokenURL = 'https://example.com/oauth/request_token';
+	protected string      $revokeURL       = 'https://example.com/oauth/revoke';
+	protected string      $apiURL          = 'https://api.example.com';
+	protected string|null $userRevokeURL   = 'https://account.example.com/apps/';
 
 	/**
 	 * @inheritDoc
diff --git a/tests/Core/DummyOAuth2BasicProvider.php b/tests/Core/DummyOAuth2BasicProvider.php
index f98600a6..a660f3d0 100644
--- a/tests/Core/DummyOAuth2BasicProvider.php
+++ b/tests/Core/DummyOAuth2BasicProvider.php
@@ -18,9 +18,9 @@
  */
 final class DummyOAuth2BasicProvider extends OAuth2Provider{
 
-	protected string  $authURL        = 'https://example.com/oauth2/authorize';
-	protected string  $accessTokenURL = 'https://example.com/oauth2/token';
-	protected string  $apiURL         = 'https://api.example.com/';
-	protected ?string $userRevokeURL  = 'https://account.example.com/apps/';
+	protected string      $authURL        = 'https://example.com/oauth2/authorize';
+	protected string      $accessTokenURL = 'https://example.com/oauth2/token';
+	protected string      $apiURL         = 'https://api.example.com/';
+	protected string|null $userRevokeURL  = 'https://account.example.com/apps/';
 
 }
diff --git a/tests/Core/DummyOAuth2Provider.php b/tests/Core/DummyOAuth2Provider.php
index 0938d35e..dd85929c 100644
--- a/tests/Core/DummyOAuth2Provider.php
+++ b/tests/Core/DummyOAuth2Provider.php
@@ -19,14 +19,15 @@
  */
 final class DummyOAuth2Provider extends OAuth2Provider implements ClientCredentials, CSRFToken, TokenRefresh, TokenInvalidate{
 
-	protected string  $authURL        = 'https://example.com/oauth2/authorize';
-	protected string  $accessTokenURL = 'https://example.com/oauth2/token';
-	protected string  $revokeURL      = 'https://example.com/oauth2/revoke';
-	protected string  $apiURL         = 'https://api.example.com/';
-	protected ?string $userRevokeURL  = 'https://account.example.com/apps/';
-	protected array   $authHeaders    = ['foo' => 'bar'];
-	protected array   $apiHeaders     = ['foo' => 'bar'];
-	protected int     $authMethod     = self::AUTH_METHOD_QUERY;
+	public const AUTH_METHOD  = self::AUTH_METHOD_QUERY;
+	public const HEADERS_AUTH = ['foo' => 'bar'];
+	public const HEADERS_API  = ['foo' => 'bar'];
+
+	protected string      $authURL        = 'https://example.com/oauth2/authorize';
+	protected string      $accessTokenURL = 'https://example.com/oauth2/token';
+	protected string      $revokeURL      = 'https://example.com/oauth2/revoke';
+	protected string      $apiURL         = 'https://api.example.com/';
+	protected string|null $userRevokeURL  = 'https://account.example.com/apps/';
 
 	/**
 	 * @inheritDoc
diff --git a/tests/Providers/OAuth2ProviderTestAbstract.php b/tests/Providers/OAuth2ProviderTestAbstract.php
index ea50163e..909ef3d9 100644
--- a/tests/Providers/OAuth2ProviderTestAbstract.php
+++ b/tests/Providers/OAuth2ProviderTestAbstract.php
@@ -107,19 +107,19 @@ public function testGetRequestAuthorization():void{
 		$request = $this->requestFactory->createRequest('GET', 'https://foo.bar');
 		$token   = new AccessToken(['accessTokenSecret' => 'test_token_secret', 'accessToken' => 'test_token']);
 
-		$authMethod = $this->getReflectionProperty('authMethod');
+		$authMethod = $this->provider::AUTH_METHOD;
 
 		// header (default)
 		if($authMethod === OAuth2Interface::AUTH_METHOD_HEADER){
 			$this::assertStringContainsString(
-				$this->getReflectionProperty('authMethodHeader').' test_token',
+				$this->provider::AUTH_PREFIX_HEADER.' test_token',
 				$this->provider->getRequestAuthorization($request, $token)->getHeaderLine('Authorization')
 			);
 		}
 		// query
 		elseif($authMethod === OAuth2Interface::AUTH_METHOD_QUERY){
 			$this::assertStringContainsString(
-				$this->getReflectionProperty('authMethodQuery').'=test_token',
+				$this->provider::AUTH_PREFIX_QUERY.'=test_token',
 				$this->provider->getRequestAuthorization($request, $token)->getUri()->getQuery()
 			);
 		}
@@ -133,18 +133,6 @@ public function testRequest():void{
 		$this::assertSame('such data! much wow!', MessageUtil::decodeJSON($this->provider->request('/request'))->data);
 	}
 
-	public function testRequestInvalidAuthTypeException():void{
-		$this->expectException(OAuthException::class);
-		$this->expectExceptionMessage('invalid auth type');
-
-		$this->setReflectionProperty('authMethod', -1);
-
-		$token = new AccessToken(['accessToken' => 'test_access_token_secret', 'expires' => 1]);
-		$this->provider->storeAccessToken($token);
-
-		$this->provider->request('/request');
-	}
-
 	public function testCheckCSRFState():void{
 
 		if(!$this->provider instanceof CSRFToken){
diff --git a/tests/Providers/Unit/MailChimpTest.php b/tests/Providers/Unit/MailChimpTest.php
index 397f38df..2116117c 100644
--- a/tests/Providers/Unit/MailChimpTest.php
+++ b/tests/Providers/Unit/MailChimpTest.php
@@ -56,17 +56,6 @@ public function testRequest():void{
 		$this::assertSame('such data! much wow! (/3.0/)', MessageUtil::decodeJSON($this->provider->request('/3.0/'))->data);
 	}
 
-	public function testRequestInvalidAuthTypeException():void{
-		$this->expectException(OAuthException::class);
-		$this->expectExceptionMessage('invalid auth type');
-
-		$this->setReflectionProperty('authMethod', -1);
-
-		$this->storage->storeAccessToken($this->token, $this->provider->serviceName);
-
-		$this->provider->request('');
-	}
-
 	public function testGetTokenMetadata():void{
 		$token = $this->provider->getTokenMetadata($this->token);
 
diff --git a/tests/Providers/Unit/NPROneTest.php b/tests/Providers/Unit/NPROneTest.php
index 87c1988e..3953ef1c 100644
--- a/tests/Providers/Unit/NPROneTest.php
+++ b/tests/Providers/Unit/NPROneTest.php
@@ -46,18 +46,6 @@ protected function getProviderFQCN():string{
 		return NPROne::class;
 	}
 
-	public function testRequestInvalidAuthTypeException():void{
-		$this->expectException(OAuthException::class);
-		$this->expectExceptionMessage('invalid auth type');
-
-		$this->setReflectionProperty('authMethod', -1);
-
-		$token = new AccessToken(['accessToken' => 'test_access_token_secret', 'expires' => 1]);
-		$this->storage->storeAccessToken($token, $this->provider->serviceName);
-
-		$this->provider->request('https://foo.api.npr.org/');
-	}
-
 	public static function requestTargetProvider():array{
 		return [
 			'empty'          => ['', 'https://localhost/api'],