Private rails for the agentic economy on Solana.

Stealth addresses and x402 payments for AI agents — every payment lands at a fresh, single-use address that only the recipient can spend, so who paid whom, and how much, never reaches the public ledger.

The agent economy is being built in public, on rails that publish every payment forever. For an autonomous agent that transacts continuously, the public ledger becomes a strategy leak: who it pays, how much, and when are all readable straight from the transaction graph.

ProwlFi closes that gap at the address layer. It combines two primitives:

• Stealth addresses — the recipient publishes one long-lived meta-address; senders derive a fresh, single-use destination for every payment that cannot be linked to one another or back to the recipient.
• x402 payments — the dormant HTTP 402 Payment Required status code, turned into a working machine-to-machine settlement layer so one agent can pay another over plain HTTP, with the payment landing at a stealth address.

The result: agents keep operating on standard Solana — standard wallets, standard SPL tokens — without surrendering their strategy to anyone with a block explorer. An operator retains a viewing key for a complete, attributable audit trail, so ProwlFi is private from the public, not from you. It is confidentiality infrastructure, not a mixer.

• Single-use stealth addresses — derived per payment on ed25519, no reuse, no clustering.
• x402 stealth payments — pay any agent endpoint over HTTP; settlement lands at a fresh address.
• View-tag scanning — one-byte view tags discard ~99.6% of announcements before any derivation.
• Viewing keys — selective disclosure: export a deterministic audit trail without revealing strategy.
• Gasless sweeps — SOL and SPL, fee-sponsored, so no SOL needs to be pre-funded at a destination.
• Non-custodial — spending keys are derived from your seed and never leave your process.
• Three surfaces — TypeScript SDK, MCP server, and a REST API. Same engine, same guarantees.

npm install @prowlfi/sdk

import { createProwl } from "@prowlfi/sdk";

const agent = createProwl({ chain: "solana" });

// Resolve a recipient to a fresh, one-time stealth address and settle over x402.
const { receipt } = await agent.payX402({
  url: "https://api.vendor.xyz/infer",
  to: "prowl:vendor-7",
  amount: 0.02,
  token: "USDC",
});

// Recipient side: scan announcements with a viewing key and sweep what arrived.
const incoming = await agent.scan(agent.viewingKey());

See examples/ for runnable end-to-end flows.

This is a monorepo for the ProwlFi protocol and its agent-facing surfaces.

Something is coming. Follow @tryProwlFi for the announcement.

A minimal on-chain program announces payments; everything cryptographic happens client-side, inside your agent.

1. Publish. The recipient publishes a meta-address — prowl:<spend>.<view>.
2. Derive. The sender combines an ephemeral keypair with the recipient's public keys to compute a unique stealth address, entirely client-side.
3. Pay. Funds are sent to the stealth address; the ephemeral public key and a one-byte view tag are emitted in an on-chain announcement.
4. Scan. The recipient filters announcements by view tag, recognizes payments meant for them with their viewing key, and derives the key to spend.

on-chain program  ->  pure-TS privacy engine  ->  SDK / MCP / REST

.
├── packages/
│   ├── sdk/            # @prowlfi/sdk — client engine (derivation, x402, scan, sweep)
│   └── mcp-server/     # @prowlfi/mcp-server — MCP tools for agent hosts
├── examples/           # runnable end-to-end flows
├── docs/               # protocol documentation
└── assets/             # brand assets

• Stealth scheme and on-chain announcement program on Solana mainnet
• TypeScript SDK, MCP server, and REST surfaces
• Independent audit and sRFC submission for the stealth-address standard
• Confidential amounts (BN-254) and network-privacy relays
• Cross-SVM coverage

ProwlFi is in active development; the stealth scheme and on-chain program are scoped for third-party audit. Do not treat mainnet usage as audited until that completes. To report a vulnerability, see SECURITY.md — please do not open public issues for security reports.

Contributions are welcome. See CONTRIBUTING.md for the development workflow, and CODE_OF_CONDUCT.md.

Released under the MIT License. © ProwlFi Labs.

_{🐺 Built on Solana · prowl.finance}