diff --git a/.github/workflows/golangci-lint.yaml b/.github/workflows/golangci-lint.yaml
index e4519a7..c15563e 100644
--- a/.github/workflows/golangci-lint.yaml
+++ b/.github/workflows/golangci-lint.yaml
@@ -12,9 +12,9 @@ jobs:
     steps:
       - uses: actions/setup-go@v3
         with:
-          go-version: 1.18
+          go-version: 1.18.x
       - uses: actions/checkout@v3
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v3
         with:
-          version: v1.46
\ No newline at end of file
+          version: v1.50.0
\ No newline at end of file
diff --git a/.golangci.yaml b/.golangci.yaml
index fc94e3b..23a5ad2 100644
--- a/.golangci.yaml
+++ b/.golangci.yaml
@@ -1,6 +1,17 @@
 run:
   timeout: 3m
 go: '1.18'
+skip-dirs:
+  skip-files:
+    - "./*_test.go$"
+linters:
+  enable:
+    - whitespace
+    - gocritic
+    - prealloc
+    - unparam
+    - usestdlibvars
+    - goimports
 linters-settings:
   forbidigo:
     # Forbid the following identifiers (list of regexp).
@@ -8,4 +19,10 @@ linters-settings:
     forbid:
       - ^print.*$
       - 'fmt\.Print.*'
-    exclude_godoc_examples: false
\ No newline at end of file
+    exclude_godoc_examples: false
+  gocritic:
+    enabled-tags:
+      - diagnostic
+      - style
+      - opinionated
+      - experimental
\ No newline at end of file
diff --git a/api/lambda/handlers/tracker_test.go b/api/lambda/handlers/tracker_test.go
index 3ed1590..35ea0f5 100644
--- a/api/lambda/handlers/tracker_test.go
+++ b/api/lambda/handlers/tracker_test.go
@@ -68,7 +68,7 @@ func TestHandleLambdaEvent(t *testing.T) {
 			tracker := &parcelTrackerMock{}
 			tc.setupTrackerMock(tracker)
 
-			req := events.APIGatewayProxyRequest{Body: fmt.Sprintf(`{"track_id":["%s"]}`, tc.trackId)}
+			req := events.APIGatewayProxyRequest{Body: fmt.Sprintf(`{"track_id":[%q]}`, tc.trackId)}
 			gotResp, gotErr := Tracking(tracker, 10)(context.Background(), req)
 
 			assert.Equal(t, tc.expResp, gotResp)
diff --git a/api/rest/handlers/tracker_test.go b/api/rest/handlers/tracker_test.go
index 1cb6de1..e7ff59b 100644
--- a/api/rest/handlers/tracker_test.go
+++ b/api/rest/handlers/tracker_test.go
@@ -3,7 +3,7 @@ package handlers
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -74,7 +74,7 @@ func TestHandleRest(t *testing.T) {
 			tracker := &parcelTrackerMock{}
 			tc.setupTrackerMock(tracker)
 
-			data := strings.NewReader(fmt.Sprintf(`{"track_id":["%s"]}`, tc.testId))
+			data := strings.NewReader(fmt.Sprintf(`{"track_id":[%q]}`, tc.testId))
 
 			req, err := http.NewRequest(tc.method, "", data)
 			assert.NoError(t, err)
@@ -87,7 +87,7 @@ func TestHandleRest(t *testing.T) {
 			res := rec.Result()
 			defer res.Body.Close()
 
-			gotResp, err := ioutil.ReadAll(res.Body)
+			gotResp, err := io.ReadAll(res.Body)
 
 			assert.NoError(t, err)
 			assert.Equal(t, tc.expResp, string(gotResp))
diff --git a/cmd/rest-server/main.go b/cmd/rest-server/main.go
index dc9034a..7716696 100644
--- a/cmd/rest-server/main.go
+++ b/cmd/rest-server/main.go
@@ -31,7 +31,7 @@ func main() {
 
 	g, gCtx := errgroup.WithContext(ctx)
 	g.Go(func() error {
-		fmt.Println("Server is listening...")
+		fmt.Print("Server is listening...")
 		return httpServer.ListenAndServe()
 	})
 	g.Go(func() error {
diff --git a/logic/track.go b/logic/track.go
index a86e66b..b0aa410 100644
--- a/logic/track.go
+++ b/logic/track.go
@@ -55,13 +55,9 @@ func (p ParcelsTracker) TrackParcels(_ context.Context, parcelIds []string) (map
 	for {
 		select {
 		case err := <-chanErr:
-			{
-				return nil, err
-			}
+			return nil, err
 		case idsToCarriers := <-chanIdsToCarriers:
-			{
-				go track(idsToCarriers, chanParcels, chanErr)
-			}
+			go track(idsToCarriers, chanParcels, chanErr)
 		case parcels := <-chanParcels:
 			return parcels, nil
 		}
@@ -87,7 +83,6 @@ func (p ParcelsTracker) matchParcelIdsToCarriers(parcelIds []string, chanIdsToCa
 			defer mu.Unlock()
 			idsToCarriers[carrier] = append(idsToCarriers[carrier], parcelId)
 		}(parcelId)
-
 	}
 
 	wg.Wait()
diff --git a/pkg/determine-delivery/carriers/dhl/api_test.go b/pkg/determine-delivery/carriers/dhl/api_test.go
index aff8b3c..699e14c 100644
--- a/pkg/determine-delivery/carriers/dhl/api_test.go
+++ b/pkg/determine-delivery/carriers/dhl/api_test.go
@@ -2,9 +2,9 @@ package dhl
 
 import (
 	"errors"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -43,7 +43,7 @@ func TestApi_TrackByTrackingNumber(t *testing.T) {
 			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 				w.WriteHeader(testCase.status)
 
-				b, err := ioutil.ReadFile(testCase.file)
+				b, err := os.ReadFile(testCase.file)
 				if err != nil {
 					t.Fatal(err)
 				}
diff --git a/pkg/determine-delivery/carriers/dhl/carrier.go b/pkg/determine-delivery/carriers/dhl/carrier.go
index 5c5ebf5..9d0af23 100644
--- a/pkg/determine-delivery/carriers/dhl/carrier.go
+++ b/pkg/determine-delivery/carriers/dhl/carrier.go
@@ -10,53 +10,53 @@ import (
 )
 
 var patterns = map[string]*regexp.Regexp{
-	//It starts with 000
+	// It starts with 000
 	"start000": regexp.MustCompile(`^000`),
 
-	//It starts with JVGL
+	// It starts with JVGL
 	"startJVGL": regexp.MustCompile(`(?i)^JVGL`),
 
-	//It starts with GM
+	// It starts with GM
 	"startGM": regexp.MustCompile(`(?i)^GM`),
 
-	//It starts with LX
+	// It starts with LX
 	"startLX": regexp.MustCompile(`(?i)^LX`),
 
-	//It starts with RX
+	// It starts with RX
 	"startRX": regexp.MustCompile(`(?i)^RX`),
 
-	//It starts with 3S
+	// It starts with 3S
 	"start3S": regexp.MustCompile(`(?i)^3S`),
 
-	//It starts with JJD
+	// It starts with JJD
 	"startJJD": regexp.MustCompile(`(?i)^JJD`),
 
-	//Starts with 1 number, followed by 2 letters and 4 to 6 numbers
-	//Example: 1AB12345
-	"pattern1": regexp.MustCompile(`(?i)^[\d]{1}[a-z]{2}[\d]{4,6}$`),
+	// Starts with 1 number, followed by 2 letters and 4 to 6 numbers
+	// Example: 1AB12345
+	"pattern1": regexp.MustCompile(`(?i)^\d[a-z]{2}\d{4,6}$`),
 
-	//Starts with 3 to 4 letters
-	//Example: ABC123456
-	"pattern2": regexp.MustCompile(`(?i)^[a-z]{3}[\d]{6}$`),
+	// Starts with 3 to 4 letters
+	// Example: ABC123456
+	"pattern2": regexp.MustCompile(`(?i)^[a-z]{3}\d{6}$`),
 
-	//Starts with 3-digit carrier code, followed by hyphen (-), followed by the 8-digit masterbill number.
-	//Example: 123-12345678
-	"pattern3": regexp.MustCompile(`^[\d]{3}-[\d]{8}$`),
+	// Starts with 3-digit carrier code, followed by hyphen (-), followed by the 8-digit masterbill number.
+	// Example: 123-12345678
+	"pattern3": regexp.MustCompile(`^\d{3}-\d{8}$`),
 
-	//Order Code: starts with 2 to 3 letters, followed by hyphen (-), 2 to 3 letters, hyphen (-) and 7 numbers
-	//Example: ABC-DE-1234567
-	"pattern4": regexp.MustCompile(`(?i)^[a-z]{2,3}-[a-z]{2,3}-[\d]{7}$`),
+	// Order Code: starts with 2 to 3 letters, followed by hyphen (-), 2 to 3 letters, hyphen (-) and 7 numbers
+	// Example: ABC-DE-1234567
+	"pattern4": regexp.MustCompile(`(?i)^[a-z]{2,3}-[a-z]{2,3}-\d{7}$`),
 
-	//Starts with 4 numbers, followed by hyphen (-) and 5 numbers
-	//Example: 1234-12345
-	"pattern5": regexp.MustCompile(`^[\d]{4}-[\d]{5}$`),
+	// Starts with 4 numbers, followed by hyphen (-) and 5 numbers
+	// Example: 1234-12345
+	"pattern5": regexp.MustCompile(`^\d{4}-\d{5}$`),
 
-	//Numeric only with the length 7,9,10 or 14
-	//Example: 123456789
-	//9 and 10 in UPS as well !!!
-	"numbers7":    regexp.MustCompile(`^[\d]{7}$`),
-	"numbers9_10": regexp.MustCompile(`^[\d]{9,10}$`),
-	"numbers14":   regexp.MustCompile(`^[\d]{14}$`),
+	// Numeric only with the length 7,9,10 or 14
+	// Example: 123456789
+	// 9 and 10 in UPS as well !!!
+	"numbers7":    regexp.MustCompile(`^\d{7}$`),
+	"numbers9_10": regexp.MustCompile(`^\d{9,10}$`),
+	"numbers14":   regexp.MustCompile(`^\d{14}$`),
 }
 
 const layout = "2006-01-02T15:04:05Z"
diff --git a/pkg/determine-delivery/carriers/fedex/api.go b/pkg/determine-delivery/carriers/fedex/api.go
index fd2a348..5b4081c 100644
--- a/pkg/determine-delivery/carriers/fedex/api.go
+++ b/pkg/determine-delivery/carriers/fedex/api.go
@@ -83,7 +83,7 @@ func (api *Api) TrackByTrackingNumber(trackingRequest TrackingRequest) (*Trackin
 		return nil, err
 	}
 
-	if err = getErrors(trackingResponse.Errors); err != nil {
+	if err := getErrors(trackingResponse.Errors); err != nil {
 		return nil, err
 	}
 
@@ -142,7 +142,7 @@ func (api *Api) authorize() (string, error) {
 		if err := json.Unmarshal(response, res); err != nil {
 			return "", err
 		}
-		if err = getErrors(res.Errors); err != nil {
+		if err := getErrors(res.Errors); err != nil {
 			return "", err
 		}
 	}
diff --git a/pkg/determine-delivery/carriers/fedex/api_test.go b/pkg/determine-delivery/carriers/fedex/api_test.go
index 7c20edd..881003f 100644
--- a/pkg/determine-delivery/carriers/fedex/api_test.go
+++ b/pkg/determine-delivery/carriers/fedex/api_test.go
@@ -2,9 +2,9 @@ package fedex
 
 import (
 	"errors"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 	"time"
 
@@ -54,7 +54,7 @@ func TestApi_TrackByTrackingNumber(t *testing.T) {
 			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 				w.WriteHeader(testCase.status)
 
-				b, err := ioutil.ReadFile(testCase.file)
+				b, err := os.ReadFile(testCase.file)
 				if err != nil {
 					t.Fatal(err)
 				}
@@ -106,7 +106,7 @@ func TestApi_authorize(t *testing.T) {
 	for _, testCase := range testCases {
 		t.Run(testCase.name, func(t *testing.T) {
 			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-				b, err := ioutil.ReadFile(testCase.file)
+				b, err := os.ReadFile(testCase.file)
 				if err != nil {
 					t.Fatal(err)
 				}
diff --git a/pkg/determine-delivery/carriers/fedex/carrier.go b/pkg/determine-delivery/carriers/fedex/carrier.go
index 93f00f6..839330a 100644
--- a/pkg/determine-delivery/carriers/fedex/carrier.go
+++ b/pkg/determine-delivery/carriers/fedex/carrier.go
@@ -9,15 +9,15 @@ import (
 )
 
 var patterns = map[string]*regexp.Regexp{
-	//Numeric only with the length 12
-	"numbers12": regexp.MustCompile(`^[\d]{12}$`),
-	//Numeric only with the length 15
-	"numbers15": regexp.MustCompile(`^[\d]{15}$`),
-	//Numeric only with the length 20
-	"numbers20": regexp.MustCompile(`^[\d]{20}$`),
-	//Numeric only with the length 22
-	//22 in UPS as well !!!
-	"numbers22": regexp.MustCompile(`^[\d]{22}$`),
+	// Numeric only with the length 12
+	"numbers12": regexp.MustCompile(`^\d{12}$`),
+	// Numeric only with the length 15
+	"numbers15": regexp.MustCompile(`^\d{15}$`),
+	// Numeric only with the length 20
+	"numbers20": regexp.MustCompile(`^\d{20}$`),
+	// Numeric only with the length 22
+	// 22 in UPS as well !!!
+	"numbers22": regexp.MustCompile(`^\d{22}$`),
 }
 
 type api interface {
@@ -83,14 +83,9 @@ func (c *Carrier) track(trackNumbers []string, chanParcels chan []carriers.Parce
 				return
 			}
 
-			p, err := prepareResponse(response)
-			if err != nil {
-				chanErr <- err
-				return
-			}
 			mu.Lock()
 			defer mu.Unlock()
-			parcels = append(parcels, p...)
+			parcels = append(parcels, prepareResponse(response)...)
 		}(trackNumber)
 	}
 
@@ -98,7 +93,7 @@ func (c *Carrier) track(trackNumbers []string, chanParcels chan []carriers.Parce
 	chanParcels <- parcels
 }
 
-func prepareResponse(response *TrackingResponse) ([]carriers.Parcel, error) {
+func prepareResponse(response *TrackingResponse) []carriers.Parcel {
 	parcels := make([]carriers.Parcel, len(response.Output.CompleteTrackResults))
 	for i, d := range response.Output.CompleteTrackResults {
 		parcels[i] = carriers.Parcel{
@@ -108,7 +103,7 @@ func prepareResponse(response *TrackingResponse) ([]carriers.Parcel, error) {
 			DeliveryDate:   d.TrackResults[0].EstimatedDeliveryTimeWindow.Window.Ends,
 		}
 	}
-	return parcels, nil
+	return parcels
 }
 
 func getPlaces(result TrackResult) []carriers.Place {
diff --git a/pkg/determine-delivery/carriers/fedex/carrier_test.go b/pkg/determine-delivery/carriers/fedex/carrier_test.go
index 67ce28c..8720e39 100644
--- a/pkg/determine-delivery/carriers/fedex/carrier_test.go
+++ b/pkg/determine-delivery/carriers/fedex/carrier_test.go
@@ -44,7 +44,6 @@ func TestCarrier_Track(t *testing.T) {
 			name:         "Ok response",
 			trackNumbers: []string{"12A12345", "12A12346"},
 			setupApiMock: func(api *apiMock, trackNumbers []string) {
-
 				trackingInfo := TrackingInfo{
 					TrackingNumberInfo: TrackingNumberInfo{
 						TrackingNumber: trackNumbers[0],
diff --git a/pkg/determine-delivery/carriers/me/api.go b/pkg/determine-delivery/carriers/me/api.go
index b3c3ee3..bdc22d7 100644
--- a/pkg/determine-delivery/carriers/me/api.go
+++ b/pkg/determine-delivery/carriers/me/api.go
@@ -11,11 +11,11 @@ import (
 	"github.com/valyala/fasthttp"
 )
 
-const statusOk = "000" //Ok
+const statusOk = "000" // Ok
 
 var handleErrors = map[string]error{
-	"103": response_errors.NotFound, //Document not found
-	"104": response_errors.NotFound, //Directory not found
+	"103": response_errors.NotFound, // Document not found
+	"104": response_errors.NotFound, // Directory not found
 }
 
 type Api struct {
@@ -51,7 +51,6 @@ func (api *Api) TrackByTrackingNumber(trackNumber string) (*ShipmentsTrackRespon
 	}
 
 	if shipmentsTrackResponse.Errors.Code != statusOk {
-
 		if err, ok := handleErrors[shipmentsTrackResponse.Errors.Code]; ok {
 			return nil, err
 		}
diff --git a/pkg/determine-delivery/carriers/me/api_test.go b/pkg/determine-delivery/carriers/me/api_test.go
index 6ad34e6..ad8c127 100644
--- a/pkg/determine-delivery/carriers/me/api_test.go
+++ b/pkg/determine-delivery/carriers/me/api_test.go
@@ -2,9 +2,9 @@ package me
 
 import (
 	"errors"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -37,7 +37,7 @@ func TestApi_TrackByTrackingNumber(t *testing.T) {
 			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 				w.WriteHeader(http.StatusOK)
 
-				b, err := ioutil.ReadFile(testCase.file)
+				b, err := os.ReadFile(testCase.file)
 				if err != nil {
 					t.Fatal(err)
 				}
diff --git a/pkg/determine-delivery/carriers/me/carrier.go b/pkg/determine-delivery/carriers/me/carrier.go
index f786485..2397c5a 100644
--- a/pkg/determine-delivery/carriers/me/carrier.go
+++ b/pkg/determine-delivery/carriers/me/carrier.go
@@ -10,13 +10,13 @@ import (
 )
 
 var patterns = map[string]*regexp.Regexp{
-	//Starts with CV, 9 numbers and 2 letters at the end
-	//CV999999999AA
-	"startCV": regexp.MustCompile(`(?i)^CV[\d]{9}[a-z]{2}$`),
+	// Starts with CV, 9 numbers and 2 letters at the end
+	// CV999999999AA
+	"startCV": regexp.MustCompile(`(?i)^CV\d{9}[a-z]{2}$`),
 
-	//Starts with MYCV, 9 numbers and 2 letters at the end
-	//MYCV999999999AA
-	"startMYCV": regexp.MustCompile(`(?i)^MYCV[\d]{9}[a-z]{2}$`),
+	// Starts with MYCV, 9 numbers and 2 letters at the end
+	// MYCV999999999AA
+	"startMYCV": regexp.MustCompile(`(?i)^MYCV\d{9}[a-z]{2}$`),
 }
 
 const layout = "2016-06-30 13: 42: 11"
diff --git a/pkg/determine-delivery/carriers/me/response.go b/pkg/determine-delivery/carriers/me/response.go
index f23a960..b890c1c 100644
--- a/pkg/determine-delivery/carriers/me/response.go
+++ b/pkg/determine-delivery/carriers/me/response.go
@@ -13,25 +13,25 @@ type ShipmentsTrackResponse struct {
 }
 
 type ShipmentTrackResponse struct {
-	ShipmentIdRef         string `xml:"ShipmentIdRef"`        //0xa969003048d2b47311e3fc6109445fb1
-	DocumentIdRef         string `xml:"DocumentIdRef"`        //0xa969003048d2b47311e3fc6109445fb4
-	AgentsIdRef           string `xml:"AgentsIdRef"`          //0xb95653547d06ad014b2580d2c4be55b2
-	ShipmentNumberSender  string `xml:"ShipmentNumberSender"` //001-0255371
+	ShipmentIdRef         string `xml:"ShipmentIdRef"`        // 0xa969003048d2b47311e3fc6109445fb1
+	DocumentIdRef         string `xml:"DocumentIdRef"`        // 0xa969003048d2b47311e3fc6109445fb4
+	AgentsIdRef           string `xml:"AgentsIdRef"`          // 0xb95653547d06ad014b2580d2c4be55b2
+	ShipmentNumberSender  string `xml:"ShipmentNumberSender"` // 001-0255371
 	ShipmentNumberTransit string `xml:"ShipmentNumberTransit"`
 	ShipmentClientID      string `xml:"ShipmentClientID"`
-	DateTimeAction        string `xml:"DateTimeAction"`     //2016-06-25 15:05:53
-	Country               string `xml:"Country"`            //УКРАЇНА
-	City                  string `xml:"City"`               //Дніпродзержинськ
-	ActionId              int    `xml:"ActionId"`           //6
-	StatusCode            string `xml:"StatusCode"`         //606
-	ActionMessages_UA     string `xml:"ActionMessages_UA"`  //Поступлення відправлення на відділення
-	ActionMessages_RU     string `xml:"ActionMessages_RU"`  //Поступление отправления на отделение
-	ActionMessages_EN     string `xml:"ActionMessages_EN"`  //Accepted by the branch
-	DetailMessages_UA     string `xml:"DetailMessages_UA"`  //Дніпродзержинськ
-	DetailMessages_RU     string `xml:"DetailMessages_RU"`  //Дніпродзержинськ
-	DetailMessages_EN     string `xml:"DetailMessages_EN"`  //Дніпродзержинськ
-	DetailPlacesAction    string `xml:"DetailPlacesAction"` //1/1
-	CountryDel            string `xml:"CountryDel"`         //UA
+	DateTimeAction        string `xml:"DateTimeAction"`     // 2016-06-25 15:05:53
+	Country               string `xml:"Country"`            // УКРАЇНА
+	City                  string `xml:"City"`               // Дніпродзержинськ
+	ActionId              int    `xml:"ActionId"`           // 6
+	StatusCode            string `xml:"StatusCode"`         // 606
+	ActionMessages_UA     string `xml:"ActionMessages_UA"`  // Поступлення відправлення на відділення
+	ActionMessages_RU     string `xml:"ActionMessages_RU"`  // Поступление отправления на отделение
+	ActionMessages_EN     string `xml:"ActionMessages_EN"`  // Accepted by the branch
+	DetailMessages_UA     string `xml:"DetailMessages_UA"`  // Дніпродзержинськ
+	DetailMessages_RU     string `xml:"DetailMessages_RU"`  // Дніпродзержинськ
+	DetailMessages_EN     string `xml:"DetailMessages_EN"`  // Дніпродзержинськ
+	DetailPlacesAction    string `xml:"DetailPlacesAction"` // 1/1
+	CountryDel            string `xml:"CountryDel"`         // UA
 	Recipient_Country     string `xml:"Recipient_Country"`
 	Deliverydate          string `xml:"Deliverydate"`
 }
diff --git a/pkg/determine-delivery/carriers/np/api.go b/pkg/determine-delivery/carriers/np/api.go
index a877cc8..5f81f34 100644
--- a/pkg/determine-delivery/carriers/np/api.go
+++ b/pkg/determine-delivery/carriers/np/api.go
@@ -12,24 +12,24 @@ import (
 const URL = "/v2.0/json/"
 
 var handleErrors = map[string]error{
-	"20000500603": response_errors.NotFound,      //Not found
-	"20000300415": response_errors.NotFound,      //Document not found
-	"20000200161": response_errors.NotFound,      //Documents not found
-	"20000200157": response_errors.InvalidNumber, //Document number empty
-	"20000200158": response_errors.InvalidNumber, //Document number incorrect
-	"20001401442": response_errors.InvalidNumber, //Document number is not correct
-	"20001401158": response_errors.InvalidNumber, //Error: wrong format of the document number
-	"20000202391": response_errors.InvalidNumber, //Invalid document number
-	"20000401614": response_errors.InvalidNumber, //Wrong DocumentNumber
-	"20000401620": response_errors.InvalidNumber, //DocumentNumber is invalid
-	"20000201873": response_errors.InvalidNumber, //DocumentNumber invalid
-	"20000201994": response_errors.InvalidNumber, //Invalid DocumentNumber
-	"20002102188": response_errors.InvalidNumber, //DocumentNumber is incorrect
-	"20001402465": response_errors.InvalidNumber, //DocumentNumber invalid format
-	"20002102542": response_errors.InvalidNumber, //Invalid DocumentNumber format
-	"20002102543": response_errors.InvalidNumber, //Document not found by DocumentNumber
-	"20001402806": response_errors.InvalidNumber, //DocumentNumber invalid format.
-	"20002502852": response_errors.InvalidNumber, //DocumentNumber is empty
+	"20000500603": response_errors.NotFound,      // Not found
+	"20000300415": response_errors.NotFound,      // Document not found
+	"20000200161": response_errors.NotFound,      // Documents not found
+	"20000200157": response_errors.InvalidNumber, // Document number empty
+	"20000200158": response_errors.InvalidNumber, // Document number incorrect
+	"20001401442": response_errors.InvalidNumber, // Document number is not correct
+	"20001401158": response_errors.InvalidNumber, // Error: wrong format of the document number
+	"20000202391": response_errors.InvalidNumber, // Invalid document number
+	"20000401614": response_errors.InvalidNumber, // Wrong DocumentNumber
+	"20000401620": response_errors.InvalidNumber, // DocumentNumber is invalid
+	"20000201873": response_errors.InvalidNumber, // DocumentNumber invalid
+	"20000201994": response_errors.InvalidNumber, // Invalid DocumentNumber
+	"20002102188": response_errors.InvalidNumber, // DocumentNumber is incorrect
+	"20001402465": response_errors.InvalidNumber, // DocumentNumber invalid format
+	"20002102542": response_errors.InvalidNumber, // Invalid DocumentNumber format
+	"20002102543": response_errors.InvalidNumber, // Document not found by DocumentNumber
+	"20001402806": response_errors.InvalidNumber, // DocumentNumber invalid format.
+	"20002502852": response_errors.InvalidNumber, // DocumentNumber is empty
 }
 
 type Api struct {
@@ -86,17 +86,17 @@ func (api *Api) makeRequest(r novaPoshtaRequest, method string) ([]byte, error)
 	return res.Body(), nil
 }
 
-func getErrors(TrackingDocumentsResponse *TrackingDocumentsResponse) error {
-	for _, code := range TrackingDocumentsResponse.ErrorCodes {
+func getErrors(trackingDocumentsResponse *TrackingDocumentsResponse) error {
+	for _, code := range trackingDocumentsResponse.ErrorCodes {
 		if err, ok := handleErrors[code]; ok {
 			return err
 		}
 	}
 
-	lenErrors := len(TrackingDocumentsResponse.Errors)
+	lenErrors := len(trackingDocumentsResponse.Errors)
 	if lenErrors > 0 {
 		errorMsgs := ""
-		for i, e := range TrackingDocumentsResponse.Errors {
+		for i, e := range trackingDocumentsResponse.Errors {
 			errorMsgs += e
 			if i < -1 {
 				errorMsgs += ", "
diff --git a/pkg/determine-delivery/carriers/np/api_test.go b/pkg/determine-delivery/carriers/np/api_test.go
index 42c8565..26db433 100644
--- a/pkg/determine-delivery/carriers/np/api_test.go
+++ b/pkg/determine-delivery/carriers/np/api_test.go
@@ -1,9 +1,9 @@
 package np
 
 import (
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	response_errors "github.com/RomaBilka/parcel-tracking/pkg/response-errors"
@@ -50,7 +50,7 @@ func TestApi_TrackByTrackingNumber(t *testing.T) {
 			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 				w.WriteHeader(http.StatusOK)
 
-				b, err := ioutil.ReadFile(testCase.file)
+				b, err := os.ReadFile(testCase.file)
 				if err != nil {
 					t.Fatal(err)
 				}
@@ -71,7 +71,6 @@ func TestApi_TrackByTrackingNumber(t *testing.T) {
 			if res != nil {
 				assert.Equal(t, testCase.document.DocumentNumber, res.Data[0].Number)
 			}
-
 		})
 	}
 }
diff --git a/pkg/determine-delivery/carriers/np/carrier.go b/pkg/determine-delivery/carriers/np/carrier.go
index c568d29..6b74d5b 100644
--- a/pkg/determine-delivery/carriers/np/carrier.go
+++ b/pkg/determine-delivery/carriers/np/carrier.go
@@ -8,17 +8,17 @@ import (
 )
 
 var patterns = map[string]*regexp.Regexp{
-	//Starts with 59, length 14, only numbers
-	//59************
-	"start59": regexp.MustCompile(`^59[\d]{12}$`),
+	// Starts with 59, length 14, only numbers
+	// 59************
+	"start59": regexp.MustCompile(`^59\d{12}$`),
 
-	//Starts with 20, length 14, only numbers
-	//20************
-	"start20": regexp.MustCompile(`^20[\d]{12}$`),
+	// Starts with 20, length 14, only numbers
+	// 20************
+	"start20": regexp.MustCompile(`^20\d{12}$`),
 
-	//Starts with 1, length 14, only numbers
-	//1*************
-	"start1": regexp.MustCompile(`^1[\d]{13}$`),
+	// Starts with 1, length 14, only numbers
+	// 1*************
+	"start1": regexp.MustCompile(`^1\d{13}$`),
 }
 
 const layout = "08.03.2022 15:16:47"
@@ -66,7 +66,6 @@ func (c *Carrier) Track(trackingIds []string) ([]carriers.Parcel, error) {
 	parcels := make([]carriers.Parcel, len(response.Data))
 
 	for i, d := range response.Data {
-
 		scheduledDeliveryDate, err := helpers.ParseTime(layout, d.ScheduledDeliveryDate)
 		if err != nil {
 			return nil, err
diff --git a/pkg/determine-delivery/carriers/np/response.go b/pkg/determine-delivery/carriers/np/response.go
index 08698fe..6f59735 100644
--- a/pkg/determine-delivery/carriers/np/response.go
+++ b/pkg/determine-delivery/carriers/np/response.go
@@ -17,61 +17,61 @@ type TrackingDocumentsResponse struct {
 }
 
 type TrackingDocumentResponse struct {
-	Number                               string `json:"Number"`                               //"20400048799000"
-	Redelivery                           any    `json:"Redelivery"`                           //"0"
-	RedeliverySum                        any    `json:"RedeliverySum"`                        //"0"
-	RedeliveryNum                        string `json:"RedeliveryNum"`                        //""
-	RedeliveryPayer                      string `json:"RedeliveryPayer"`                      //"Sender/Recipient"
-	OwnerDocumentType                    string `json:"OwnerDocumentType"`                    //""
-	LastCreatedOnTheBasisDocumentType    string `json:"LastCreatedOnTheBasisDocumentType"`    //""
-	LastCreatedOnTheBasisPayerType       string `json:"LastCreatedOnTheBasisPayerType"`       //""
-	LastCreatedOnTheBasisDateTime        string `json:"LastCreatedOnTheBasisDateTime"`        //""
-	LastTransactionStatusGM              string `json:"LastTransactionStatusGM"`              //""
-	LastTransactionDateTimeGM            string `json:"LastTransactionDateTimeGM"`            //""
-	LastAmountTransferGM                 string `json:"LastAmountTransferGM"`                 //""
-	DateCreated                          string `json:"DateCreated"`                          //"18-11-2021 11:52:42"
-	DocumentWeight                       any    `json:"DocumentWeight"`                       //"3"
-	FactualWeight                        string `json:"FactualWeight"`                        //"3"
-	VolumeWeight                         string `json:"VolumeWeight"`                         //"0.1",
-	CheckWeight                          any    `json:"CheckWeight"`                          //""
-	DocumentCost                         any    `json:"DocumentCost"`                         //"51"
-	SumBeforeCheckWeight                 any    `json:"SumBeforeCheckWeight"`                 //""
-	PayerType                            string `json:"PayerType"`                            //"Sender"
-	RecipientFullName                    string `json:"RecipientFullName"`                    //"ПІБ"
-	RecipientDateTime                    string `json:"RecipientDateTime"`                    //"21.11.2021 13:53:47"
-	ScheduledDeliveryDate                string `json:"ScheduledDeliveryDate"`                //"19.11.2021 13:53:47"
-	PaymentMethod                        string `json:"PaymentMethod"`                        //"Cash"
-	CargoDescriptionString               string `json:"CargoDescriptionString"`               //"Одяг"
-	CargoType                            string `json:"CargoType"`                            //"Cargo",
-	CitySender                           string `json:"CitySender"`                           //"Київ"
-	CityRecipient                        string `json:"CityRecipient"`                        //"Київ"
-	WarehouseRecipient                   string `json:"WarehouseRecipient"`                   // "Відділення №101 (до 15 кг), Міні-відділення: вул. Велика Васильківська, 143/2, (маг. "Фора")"
-	CounterpartyType                     string `json:"CounterpartyType"`                     //"PrivatePerson"
-	AfterpaymentOnGoodsCost              any    `json:"AfterpaymentOnGoodsCost"`              //"0"
-	ServiceType                          string `json:"ServiceType"`                          //"WarehouseWarehouse"
-	UndeliveryReasonsSubtypeDescription  string `json:"UndeliveryReasonsSubtypeDescription"`  //""
-	WarehouseRecipientNumber             any    `json:"WarehouseRecipientNumber"`             //"101"
-	LastCreatedOnTheBasisNumber          string `json:"LastCreatedOnTheBasisNumber"`          //""
-	PhoneRecipient                       string `json:"PhoneRecipient"`                       //"380600000000"
-	RecipientFullNameEW                  string `json:"RecipientFullNameEW"`                  //""
-	WarehouseRecipientInternetAddressRef string `json:"WarehouseRecipientInternetAddressRef"` //"00000000-0000-0000-0000-000000000000"
-	MarketplacePartnerToken              string `json:"MarketplacePartnerToken"`              //""
-	ClientBarcode                        string `json:"ClientBarcode"`                        //""
-	RecipientAddress                     string `json:"RecipientAddress"`                     //"м. Київ, Відділення №101 (до 15 кг), Міні-відділення, вул. Велика Васильківська, 143/2"
-	CounterpartyRecipientDescription     string `json:"CounterpartyRecipientDescription"`     //"Приватна особа"
-	CounterpartySenderType               string `json:"CounterpartySenderType"`               //"PrivatePerson",
-	DateScan                             string `json:"DateScan"`                             //"0001-01-01 00:00:00"
-	PaymentStatus                        string `json:"PaymentStatus"`                        //""
-	PaymentStatusDate                    string `json:"PaymentStatusDate"`                    //""
-	AmountToPay                          string `json:"AmountToPay"`                          //""
-	AmountPaid                           string `json:"AmountPaid"`                           //""
-	Status                               string `json:"Status"`                               //""
-	StatusCode                           string `json:"StatusCode"`                           //""
-	RefEW                                string `json:"RefEW"`                                //"00000000-0000-0000-0000-000000000000"
-	BackwardDeliverySubTypesActions      string `json:"BackwardDeliverySubTypesActions"`      //""
-	BackwardDeliverySubTypesServices     string `json:"BackwardDeliverySubTypesServices"`     //""
-	UndeliveryReasons                    string `json:"UndeliveryReasons"`                    //""
-	DatePayedKeeping                     string `json:"DatePayedKeeping"`                     //""
-	ActualDeliveryDate                   string `json:"ActualDeliveryDate"`                   //""
-	WarehouseSender                      string `json:"WarehouseSender"`                      //""
+	Number                               string `json:"Number"`                               // "20400048799000"
+	Redelivery                           any    `json:"Redelivery"`                           // "0"
+	RedeliverySum                        any    `json:"RedeliverySum"`                        // "0"
+	RedeliveryNum                        string `json:"RedeliveryNum"`                        // ""
+	RedeliveryPayer                      string `json:"RedeliveryPayer"`                      // "Sender/Recipient"
+	OwnerDocumentType                    string `json:"OwnerDocumentType"`                    // ""
+	LastCreatedOnTheBasisDocumentType    string `json:"LastCreatedOnTheBasisDocumentType"`    // ""
+	LastCreatedOnTheBasisPayerType       string `json:"LastCreatedOnTheBasisPayerType"`       // ""
+	LastCreatedOnTheBasisDateTime        string `json:"LastCreatedOnTheBasisDateTime"`        // ""
+	LastTransactionStatusGM              string `json:"LastTransactionStatusGM"`              // ""
+	LastTransactionDateTimeGM            string `json:"LastTransactionDateTimeGM"`            // ""
+	LastAmountTransferGM                 string `json:"LastAmountTransferGM"`                 // ""
+	DateCreated                          string `json:"DateCreated"`                          // "18-11-2021 11:52:42"
+	DocumentWeight                       any    `json:"DocumentWeight"`                       // "3"
+	FactualWeight                        string `json:"FactualWeight"`                        // "3"
+	VolumeWeight                         string `json:"VolumeWeight"`                         // "0.1",
+	CheckWeight                          any    `json:"CheckWeight"`                          // ""
+	DocumentCost                         any    `json:"DocumentCost"`                         // "51"
+	SumBeforeCheckWeight                 any    `json:"SumBeforeCheckWeight"`                 // ""
+	PayerType                            string `json:"PayerType"`                            // "Sender"
+	RecipientFullName                    string `json:"RecipientFullName"`                    // "ПІБ"
+	RecipientDateTime                    string `json:"RecipientDateTime"`                    // "21.11.2021 13:53:47"
+	ScheduledDeliveryDate                string `json:"ScheduledDeliveryDate"`                // "19.11.2021 13:53:47"
+	PaymentMethod                        string `json:"PaymentMethod"`                        // "Cash"
+	CargoDescriptionString               string `json:"CargoDescriptionString"`               // "Одяг"
+	CargoType                            string `json:"CargoType"`                            // "Cargo",
+	CitySender                           string `json:"CitySender"`                           // "Київ"
+	CityRecipient                        string `json:"CityRecipient"`                        // "Київ"
+	WarehouseRecipient                   string `json:"WarehouseRecipient"`                   //  "Відділення №101 (до 15 кг), Міні-відділення: вул. Велика Васильківська, 143/2, (маг. "Фора")"
+	CounterpartyType                     string `json:"CounterpartyType"`                     // "PrivatePerson"
+	AfterpaymentOnGoodsCost              any    `json:"AfterpaymentOnGoodsCost"`              // "0"
+	ServiceType                          string `json:"ServiceType"`                          // "WarehouseWarehouse"
+	UndeliveryReasonsSubtypeDescription  string `json:"UndeliveryReasonsSubtypeDescription"`  // ""
+	WarehouseRecipientNumber             any    `json:"WarehouseRecipientNumber"`             // "101"
+	LastCreatedOnTheBasisNumber          string `json:"LastCreatedOnTheBasisNumber"`          // ""
+	PhoneRecipient                       string `json:"PhoneRecipient"`                       // "380600000000"
+	RecipientFullNameEW                  string `json:"RecipientFullNameEW"`                  // ""
+	WarehouseRecipientInternetAddressRef string `json:"WarehouseRecipientInternetAddressRef"` // "00000000-0000-0000-0000-000000000000"
+	MarketplacePartnerToken              string `json:"MarketplacePartnerToken"`              // ""
+	ClientBarcode                        string `json:"ClientBarcode"`                        // ""
+	RecipientAddress                     string `json:"RecipientAddress"`                     // "м. Київ, Відділення №101 (до 15 кг), Міні-відділення, вул. Велика Васильківська, 143/2"
+	CounterpartyRecipientDescription     string `json:"CounterpartyRecipientDescription"`     // "Приватна особа"
+	CounterpartySenderType               string `json:"CounterpartySenderType"`               // "PrivatePerson",
+	DateScan                             string `json:"DateScan"`                             // "0001-01-01 00:00:00"
+	PaymentStatus                        string `json:"PaymentStatus"`                        // ""
+	PaymentStatusDate                    string `json:"PaymentStatusDate"`                    // ""
+	AmountToPay                          string `json:"AmountToPay"`                          // ""
+	AmountPaid                           string `json:"AmountPaid"`                           // ""
+	Status                               string `json:"Status"`                               // ""
+	StatusCode                           string `json:"StatusCode"`                           // ""
+	RefEW                                string `json:"RefEW"`                                // "00000000-0000-0000-0000-000000000000"
+	BackwardDeliverySubTypesActions      string `json:"BackwardDeliverySubTypesActions"`      // ""
+	BackwardDeliverySubTypesServices     string `json:"BackwardDeliverySubTypesServices"`     // ""
+	UndeliveryReasons                    string `json:"UndeliveryReasons"`                    // ""
+	DatePayedKeeping                     string `json:"DatePayedKeeping"`                     // ""
+	ActualDeliveryDate                   string `json:"ActualDeliveryDate"`                   // ""
+	WarehouseSender                      string `json:"WarehouseSender"`                      // ""
 }
diff --git a/pkg/determine-delivery/carriers/ukrposhta/api_test.go b/pkg/determine-delivery/carriers/ukrposhta/api_test.go
index 94a37f8..a62bf8e 100644
--- a/pkg/determine-delivery/carriers/ukrposhta/api_test.go
+++ b/pkg/determine-delivery/carriers/ukrposhta/api_test.go
@@ -1,9 +1,9 @@
 package ukrposhta
 
 import (
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -31,7 +31,7 @@ func TestApi_TrackByTrackingNumber(t *testing.T) {
 			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 				w.WriteHeader(http.StatusOK)
 
-				b, err := ioutil.ReadFile(testCase.file)
+				b, err := os.ReadFile(testCase.file)
 				if err != nil {
 					t.Fatal(err)
 				}
diff --git a/pkg/determine-delivery/carriers/ukrposhta/carrier.go b/pkg/determine-delivery/carriers/ukrposhta/carrier.go
index dc72745..e59da2f 100644
--- a/pkg/determine-delivery/carriers/ukrposhta/carrier.go
+++ b/pkg/determine-delivery/carriers/ukrposhta/carrier.go
@@ -8,11 +8,11 @@ import (
 )
 
 var patterns = map[string]*regexp.Regexp{
-	//Starts with 2 letters 9 numbers and ends with 2 letters
-	"pattern1": regexp.MustCompile(`(?i)^[a-z]{2}[\d]{9}[a-z]{2}$`),
+	// Starts with 2 letters 9 numbers and ends with 2 letters
+	"pattern1": regexp.MustCompile(`(?i)^[a-z]{2}\d{9}[a-z]{2}$`),
 
-	//Numeric only with the length 13
-	"numbers13": regexp.MustCompile(`^[\d]{13}$`),
+	// Numeric only with the length 13
+	"numbers13": regexp.MustCompile(`^\d{13}$`),
 }
 
 const layout = "2019-02-07T16:36:00"
diff --git a/pkg/determine-delivery/carriers/ups/api.go b/pkg/determine-delivery/carriers/ups/api.go
index dc2c3fb..fbff4e5 100644
--- a/pkg/determine-delivery/carriers/ups/api.go
+++ b/pkg/determine-delivery/carriers/ups/api.go
@@ -10,15 +10,15 @@ import (
 )
 
 var handleErrors = map[string]error{
-	"150022": response_errors.InvalidNumber, //Invalid tracking number
-	"150028": response_errors.InvalidNumber, //Hard Invalid shipper number length
-	"151018": response_errors.InvalidNumber, //Invalid tracking number
-	"151044": response_errors.NotFound,      //No tracking information available
-	"151045": response_errors.NotFound,      //No information found
-	"151062": response_errors.NotFound,      //No tracking information available
-	"151068": response_errors.InvalidNumber, //Invalid Shipper Number
-	"152110": response_errors.NotFound,      //No information found for reference number
-	"154030": response_errors.NotFound,      //No information for this tracking number
+	"150022": response_errors.InvalidNumber, // Invalid tracking number
+	"150028": response_errors.InvalidNumber, // Hard Invalid shipper number length
+	"151018": response_errors.InvalidNumber, // Invalid tracking number
+	"151044": response_errors.NotFound,      // No tracking information available
+	"151045": response_errors.NotFound,      // No information found
+	"151062": response_errors.NotFound,      // No tracking information available
+	"151068": response_errors.InvalidNumber, // Invalid Shipper Number
+	"152110": response_errors.NotFound,      // No information found for reference number
+	"154030": response_errors.NotFound,      // No information for this tracking number
 
 }
 
diff --git a/pkg/determine-delivery/carriers/ups/api_test.go b/pkg/determine-delivery/carriers/ups/api_test.go
index 210d1ea..a213a09 100644
--- a/pkg/determine-delivery/carriers/ups/api_test.go
+++ b/pkg/determine-delivery/carriers/ups/api_test.go
@@ -1,9 +1,9 @@
 package ups
 
 import (
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	response_errors "github.com/RomaBilka/parcel-tracking/pkg/response-errors"
@@ -32,7 +32,7 @@ func TestApi_TrackByTrackingNumber(t *testing.T) {
 	for _, testCase := range testCases {
 		t.Run(testCase.name, func(t *testing.T) {
 			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-				b, err := ioutil.ReadFile(testCase.file)
+				b, err := os.ReadFile(testCase.file)
 				if err != nil {
 					t.Fatal(err)
 				}
diff --git a/pkg/determine-delivery/carriers/ups/carrier.go b/pkg/determine-delivery/carriers/ups/carrier.go
index 2527839..04a3736 100644
--- a/pkg/determine-delivery/carriers/ups/carrier.go
+++ b/pkg/determine-delivery/carriers/ups/carrier.go
@@ -9,34 +9,34 @@ import (
 )
 
 var patterns = map[string]*regexp.Regexp{
-	//Starts with 1Z, 5 or 6 digits, 1 letter and 9 or 10 digits, length 18
-	//1Z12345E6605272234
-	"start1z": regexp.MustCompile(`(?i)^1Z[\d]{5,6}[a-z]{1}[\d]{9,10}$`),
-
-	//Starts with 1Z, 4 digits, WWE and 9 digits, length 18
-	//1Z4861WWE194914215
-	"WWE": regexp.MustCompile(`(?i)^1Z[\d]{4}WWE[\d]{9}$`),
-
-	//Starts with 1ZWX, 4 digits, 2 letters and 8 digits, length 18
-	//1ZWX0692YP40636269
-	"start1ZWX": regexp.MustCompile(`(?i)^1ZWX[\d]{4}[a-z]{2}[\d]{8}$`),
-
-	//Starts with ER and 15 digits, length 17
-	//ER751105042015062
-	"startER": regexp.MustCompile(`(?i)^ER[\d]{15}`),
-
-	//Numeric only with the length 9 or 10
-	//Example: 123456789
-	//9 and 10 in DHL as well !!!
-	"numbers9_10": regexp.MustCompile(`^[\d]{9,10}$`),
-
-	//Numeric only with the length 22
-	//22 in Fedex as well !!!
-	"numbers22": regexp.MustCompile(`^[\d]{22}$`),
-
-	//Starts with cgish and 9 digits
-	//cgish000116630
-	"startCGISH": regexp.MustCompile(`(?i)^cgish[\d]{9}$`),
+	// Starts with 1Z, 5 or 6 digits, 1 letter and 9 or 10 digits, length 18
+	// 1Z12345E6605272234
+	"start1z": regexp.MustCompile(`(?i)^1Z\d{5,6}[a-z]\d{9,10}$`),
+
+	// Starts with 1Z, 4 digits, WWE and 9 digits, length 18
+	// 1Z4861WWE194914215
+	"WWE": regexp.MustCompile(`(?i)^1Z\d{4}WWE\d{9}$`),
+
+	// Starts with 1ZWX, 4 digits, 2 letters and 8 digits, length 18
+	// 1ZWX0692YP40636269
+	"start1ZWX": regexp.MustCompile(`(?i)^1ZWX\d{4}[a-z]{2}\d{8}$`),
+
+	// Starts with ER and 15 digits, length 17
+	// ER751105042015062
+	"startER": regexp.MustCompile(`(?i)^ER\d{15}`),
+
+	// Numeric only with the length 9 or 10
+	// Example: 123456789
+	// 9 and 10 in DHL as well !!!
+	"numbers9_10": regexp.MustCompile(`^\d{9,10}$`),
+
+	// Numeric only with the length 22
+	// 22 in Fedex as well !!!
+	"numbers22": regexp.MustCompile(`^\d{22}$`),
+
+	// Starts with cgish and 9 digits
+	// cgish000116630
+	"startCGISH": regexp.MustCompile(`(?i)^cgish\d{9}$`),
 }
 
 type api interface {
diff --git a/pkg/determine-delivery/carriers/usps/api.go b/pkg/determine-delivery/carriers/usps/api.go
index 5886528..6782f02 100644
--- a/pkg/determine-delivery/carriers/usps/api.go
+++ b/pkg/determine-delivery/carriers/usps/api.go
@@ -14,11 +14,11 @@ type Api struct {
 	sourceId string
 }
 
-func NewApi(apiURL, userId, SourceId string) *Api {
+func NewApi(apiURL, userId, sourceId string) *Api {
 	return &Api{
 		apiURL:   apiURL,
 		userId:   userId,
-		sourceId: SourceId,
+		sourceId: sourceId,
 	}
 }
 
diff --git a/pkg/determine-delivery/carriers/usps/api_test.go b/pkg/determine-delivery/carriers/usps/api_test.go
index 16c9b41..655c856 100644
--- a/pkg/determine-delivery/carriers/usps/api_test.go
+++ b/pkg/determine-delivery/carriers/usps/api_test.go
@@ -1,9 +1,9 @@
 package usps
 
 import (
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -33,7 +33,7 @@ func TestApi_TrackByTrackingNumber(t *testing.T) {
 	for _, testCase := range testCases {
 		t.Run(testCase.name, func(t *testing.T) {
 			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-				b, err := ioutil.ReadFile(testCase.file)
+				b, err := os.ReadFile(testCase.file)
 				if err != nil {
 					t.Fatal(err)
 				}
diff --git a/pkg/determine-delivery/carriers/usps/carrier.go b/pkg/determine-delivery/carriers/usps/carrier.go
index 7310318..e120c1a 100644
--- a/pkg/determine-delivery/carriers/usps/carrier.go
+++ b/pkg/determine-delivery/carriers/usps/carrier.go
@@ -7,39 +7,39 @@ import (
 )
 
 var patterns = map[string]*regexp.Regexp{
-	//	9400100000000000000000 length 22
-	"start94001": regexp.MustCompile(`(?i)^94001[\d]{17}$`),
+	// 9400100000000000000000 length 22
+	"start94001": regexp.MustCompile(`(?i)^94001\d{17}$`),
 
-	//	9205500000000000000000 length 22
-	"start92055": regexp.MustCompile(`(?i)^92055[\d]{17}$`),
+	// 9205500000000000000000 length 22
+	"start92055": regexp.MustCompile(`(?i)^92055\d{17}$`),
 
-	//	9407300000000000000000 length 22
-	"start94073": regexp.MustCompile(`(?i)^94073[\d]{17}$`),
+	// 9407300000000000000000 length 22
+	"start94073": regexp.MustCompile(`(?i)^94073\d{17}$`),
 
-	//	9303300000000000000000 length 22
-	"start93033": regexp.MustCompile(`(?i)^93033[\d]{17}$`),
+	// 9303300000000000000000 length 22
+	"start93033": regexp.MustCompile(`(?i)^93033\d{17}$`),
 
-	//	9208800000000000000000 length 22
-	"start92088": regexp.MustCompile(`(?i)^92088[\d]{17}$`),
+	// 9208800000000000000000 length 22
+	"start92088": regexp.MustCompile(`(?i)^92088\d{17}$`),
 
-	//	9202100000000000000000 length 22
-	"start92021": regexp.MustCompile(`(?i)^92021[\d]{17}$`),
+	// 9202100000000000000000 length 22
+	"start92021": regexp.MustCompile(`(?i)^92021\d{17}$`),
 
-	//	9270100000000000000000 length 22
-	"start92701": regexp.MustCompile(`(?i)^92701[\d]{17}$`),
+	// 9270100000000000000000 length 22
+	"start92701": regexp.MustCompile(`(?i)^92701\d{17}$`),
 
-	//	EC000000000US length 13
-	"startEC_endUS": regexp.MustCompile(`(?i)^EC[\d]{9}US$`),
+	// EC000000000US length 13
+	"startEC_endUS": regexp.MustCompile(`(?i)^EC\d{9}US$`),
 
-	//	EA000000000US length 13
-	"startEA_endUS": regexp.MustCompile(`(?i)^EA[\d]{9}US$`),
+	// EA000000000US length 13
+	"startEA_endUS": regexp.MustCompile(`(?i)^EA\d{9}US$`),
 
-	//	CP000000000US length 13
-	"startCP_endUS": regexp.MustCompile(`(?i)^CP[\d]{9}US$`),
+	// CP000000000US length 13
+	"startCP_endUS": regexp.MustCompile(`(?i)^CP\d{9}US$`),
 
-	//	8200000000 length 10
-	//10 in UPS and DHL as well !!!
-	"start80": regexp.MustCompile(`(?i)^82[\d]{8}$`),
+	// 8200000000 length 10
+	// 10 in UPS and DHL as well !!!
+	"start80": regexp.MustCompile(`(?i)^82\d{8}$`),
 }
 
 type api interface {