x402
Open HTTP payment standard so agents can pay for APIs per request in stablecoins.
Updated
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Use cases
About x402
x402 is listed in our crypto category and is aimed at builders. Open HTTP payment standard so agents can pay for APIs per request in stablecoins. Pricing, as the maker states it: Open standard. Maturity: Active. We last checked the official link on 2026-10-16.
What is x402?
x402 is an open standard for internet-native payments. It uses HTTP 402 so clients and servers can settle payments inside a normal request flow, aiming to support crypto and fiat networks and forms of value such as stablecoins, tokens and fiat.
The project ships reference SDKs in TypeScript, Python and Go. Sellers add payment middleware to an endpoint; unpaid requests get HTTP 402 and can pay (commonly in stablecoins) and retry. Principles on the official README include remaining an open standard, staying HTTP-native, and staying network-, token- and currency-agnostic.
Sources: the official README and our directory listing, checked 2026-10-18. Official site: x402.org.
Who is x402 for?
Developers and agent builders who want APIs or digital services paid per request without accounts, API keys or prepaid credits.
x402 at a glance
- Open source: Yes (Apache License 2.0)
- GitHub: x402-foundation/x402 · 6,744 stars (as of Oct 21, 2026)
Key features
- Open HTTP payment standard (HTTP 402)
- Reference SDKs in TypeScript, Python and Go
- Network-, token- and currency-agnostic design
- Aimed at API monetization and agentic commerce
x402 FAQ
What is x402?
x402 is an open standard for internet-native payments. It uses HTTP 402 so clients and servers can settle payments inside a normal request flow, aiming to support crypto and fiat networks and forms of value such as stablecoins, tokens and fiat.
Who is x402 for?
Developers and agent builders who want APIs or digital services paid per request without accounts, API keys or prepaid credits.
Is x402 free?
x402's pricing, as the maker states it: Open standard. Check the official site for current plans.
Is x402 open source?
Yes. x402 is released under the Apache License 2.0, according to its GitHub repository.
Is x402 free to use?
The protocol itself is an open standard with zero protocol fees; you still pay the underlying payment-network fees for each transfer.
Which languages have SDKs?
Official reference packages are available for TypeScript, Python and Go, with middleware examples for common web frameworks.
What is it used for?
The project docs name API monetization, agentic commerce, paywalled content and other cases where traditional checkout is too slow or heavy.
What are alternatives to x402?
Similar tools include Binance Agent OS, Crossmint for AI Agents, Skyfire, Wren x402 Doctor, Coinbase Agentic Wallet MCP and Proof x401.
x402 ratings and reviews
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x402 alternatives
Other crypto tools in our directory. See all crypto tools →
Binance Agent OS
Binance developer platform connecting AI agents to trading, market data, Agentic Wallet, x402 payments and on-chain services via MCP, APIs and skills.
Crossmint for AI Agents
Wallets, stablecoin payments and checkout APIs built for AI agents.
Skyfire
Gives AI agents verified identity and payment credentials so they can access and pay for services across the web.
Wren x402 Doctor
Wren x402 Doctor helps sellers of x402 pay-per-call endpoints, the payment standard AI agents use to pay for APIs in USDC, get listed in the Coinbase CDP Bazaar and stay listed. A free lint checks a 402 response against the x402 v2 spec and the Bazaar listing rules (networks, amounts, payTo checksum, description length, injection-like text, schema and metadata), and now also checks a seller's OpenAPI and x402 discovery documents. A paid health check returns every Bazaar listing for your wallet address with 30-day calls, unique payers and an estimated delisting date, and a paid market check (GET /market) returns up to 20 comparable live Bazaar listings with USD price, 30-day calls and payers, plus price quartiles.
Coinbase Agentic Wallet MCP
Coinbase's MCP server and wallet app (formerly Payments MCP) that let agents hold USDC and pay for x402 services on Base, Polygon and Solana within spend limits you set.
Proof x401
Open HTTP protocol and MCP server that let a website ask an AI agent to prove who it is acting for and have the person cryptographically sign the exact transaction terms, using Proof's agent identity wallet.
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