payment protocol

x402

Coinbase

x402 revives the HTTP 402 status code as a stablecoin payment protocol. A server requires payment, the agent or client pays in USDC (typically on Base), the request proceeds — settlement is transport-layer concern, not application code.

Live Official site Documentation Updated today
Adoption
Updated 1d ago
Avg payment size
$0
Daily x402 calls
~2.1M
Across testnet + early mainnet
Protocol details

Protocol details

Version
1.0
Settlement latency
~2 seconds (Base L2 confirmation)
Payment methods
USDCEURC (planned)
Company

Coinbase Global Inc.

Country
United States
HQ
Remote-first / San Francisco
Founded
May 15, 2012
Structure
public
Key people
  • Erik Reppel Project lead
  • Brian Armstrong Coinbase CEO
Timeline

Timeline

  1. May 20, 2025
    x402 spec v0.1 published
  2. Sep 15, 2025
    Base testnet integration
  3. Feb 10, 2026
    x402 v1.0 mainnet stable
  4. Apr 22, 2026
    Stripe pilot for HTTP 402 checkout
Funding and investors

Funding and investors

Investors
Coinbase Ventures (parent)
SDKs and products

SDKs and products

Products
  • x402 spec & reference impl
  • x402 middleware (Express/Fastify/Next)
  • x402 facilitator nodes
SDK languages
TypeScriptPythonGoRust
Stablecoins and chains

Stablecoins and chains

Stablecoins
usdc
Chains
base ethereum
Notable users

Notable users

Users
  • AI agent demos at Coinbase Build 2025
  • Several Y Combinator W26 AI startups
  • Foundation models behind paywalls
Integrations
  • Coinbase Wallet
  • Phantom (planned)
  • Vercel AI SDK
  • LangChain
Security and audits

Security and audits

Bug bounty (max): $250,000
Risk notes

Risk notes

  • ● Spec still evolving — breaking changes possible before 2.0
  • ● Liquidity concentrated on Base; multi-chain support nascent
  • ● Idempotency edge cases at high throughput
Competitors

Competitors

SkyfireHallidayCoinbase Agent Payments (sibling product)
Resources

Resources

Notes

More on agent payments in the AI payments deep dive and the use case.