Developer Tool for Programmable Money Payments

pay

The missing payment layer for HTTP. pay handles x402 and MPP payment challenges with user-authorized stablecoin signing.

Wrap a selected set of command line tools (curl, claude, codex, whoami, etc.) -- when a stablecoin-gated API returns 402, pay detects the payment protocol, prepares the stablecoin transaction, asks the local wallet to authorize and sign it, then retries with the payment proof.

Install · Quick Start · Docs

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SH
# Without pay — you get a 402  
curl https://debugger.pay.sh/mpp/quote/AAPL

# With pay -- it handles the 402 challenge and returns the response  
pay --sandbox curl https://debugger.pay.sh/mpp/quote/AAPL  

Key Features

💵 Transparent 402 Handling

Wrap your CLI (curl, claude, codex, etc.) -- when an API returns 402, pay detects the payment protocol, prepares the stablecoin transaction, asks the local wallet to authorize and sign it, then retries with the payment proof.

Supports both live payment standards on Solana:

• MPP — Machine Payments Protocol
• x402 — x402 Payment Protocol

Stablecoins deployed to Solana are supported out of the box.

🤖 AI-Native with MCP

pay ships with a built-in MCP server, letting AI assistants request paid API calls through the same local wallet-approval flow.

SH
# Run Claude Code or Codex with pay injected into the agent session  
pay claude  
pay codex  

🛠️ Payment debugging and simulations

pay ships with an embedded Payment Debugger — a local web UI that visualizes every 402 challenge-response cycle as a sequence diagram. See exactly which headers were sent, which protocol was used (MPP or x402), and where things went wrong.

Everything runs locally — no data leaves your machine.

SH
# Start a gateway with the debugger on any API spec  
pay server start --debugger spec.yml

# Or run the bundled demo (sandbox + debugger + sample endpoints)  
pay server demo  

A public debugger is also available.

🔐 Gated Payments via Biometrics

pay lets AI agents use paid APIs without giving them your private key or an API-wide spending credential.

When a command, Claude Code, Codex, or another MCP client hits a paid endpoint, pay prepares the payment locally and asks your wallet backend to authorize the signature. On macOS, that means Touch ID via Keychain. On Windows, Windows Hello. On Linux, GNOME Keyring / polkit. If you reject the prompt, the payment is not signed and the request does not go through.

SH
pay setup    # Touch ID on macOS, Windows Hello on Windows, GNOME Keyring on Linux, or choose 1Password  

📚 Open Source Catalog

The paid API catalog is open source in the pay-skills repo.

Anyone can contribute a provider listing, improve endpoint metadata, or add usage guidance for agents. Catalog entries follow the pay-skills contributing guide, which defines the metadata, pricing, endpoint, and usage-note standards that keep Agent experience consistent.

SH
  pay skills search "maps"  

Good catalog entries make paid APIs easier for both humans and agents to discover, compare, and use safely.

Installation

Prebuilt Binaries

SH
# macOS  
brew install pay

# via NPM  
npm install -g @solana/pay  

From Source

SH
git clone https://github.com/solana-foundation/pay.git  
cd pay  
just install pay  

Verify

SH
pay --version  

Quick Start

SH
# 1. Setup your account  
pay setup  
pay whoami

# 2. Make a paid gated API call to https://debugger.pay.sh sandbox endpoints  
pay --sandbox curl https://debugger.pay.sh/mpp/quote/AAPL

# 3. Or let your AI agent handle it  
pay claude  

Contributing

SH
cd rust  
just build   # release binary  
just test    # all tests  
just lint    # clippy (warnings = errors)  

We welcome contributions — check open issues to get started.

Troubleshooting

Linux: pay topup or pay curl errors with "auth failed"

GNOME Keyring auth uses polkit, which requires a one-time setup step:

SH
sudo cp rust/config/polkit/sh.pay.unlock-keypair.policy /usr/share/polkit-1/actions/  

This grants pay the right to prompt for your password or fingerprint before accessing the keypair.

License

MIT — see LICENSE.

Subject to the foregoing, the Terms of Service available at solana.com/tos

Source: https://github.com/solana-foundation/pay