Cowrie Research

t402

3 min read

t402

  • Name: t402
  • URL: https://t402.io/
  • Category: open payment protocol / multi-chain stablecoin payment-auth infrastructure / facilitator-and-agent-payments stack
  • Tags: bitcoin-ecosystem ethereum-ecosystem solana-ecosystem
  • Summary: t402 is a facilitator-first paid-request stack. It packages the 402 -> sign -> verify -> settle path, ships chain-specific payment modules and HTTP middleware, and layers wallet tooling and agent integrations on top. Real infrastructure, but still mostly operating glue around a paid-request flow rather than a canonical standard in its own right.
  • What it does:
    • Defines an HTTP-native paid-resource flow where servers advertise payment requirements, clients sign payment authorizations, and facilitators verify and settle the corresponding onchain payment before the resource server returns content
    • Ships chain- and scheme-specific packages spanning EVM, Solana, TON, TRON, NEAR, Aptos, Tezos, Polkadot, Stacks, Cosmos, Stellar, and Bitcoin/Lightning, with the docs emphasizing USDT coverage across many blockchain families
    • Provides server integrations for frameworks like Express, Next.js, Hono, and Fastify plus client wrappers for Fetch and Axios so developers can gate APIs and other HTTP resources behind programmable payments
    • Exposes a facilitator API and a documented self-hosting path for payment verification, settlement, metrics, rate limiting, wallet management, and production operations
    • Integrates with Tether WDK for wallet management and ERC-4337 gasless flows, and separately ships MCP tooling so AI agents can discover and pay for APIs autonomously with spending controls
    • Positions itself for API monetization, premium content, micropayments, and machine- or agent-driven paid access rather than only conventional human checkout
  • Key claims:
    • The docs homepage calls t402 “the open payment protocol for USDT” and says it enables stablecoin payments across 13 blockchain families with a single HTTP header
    • The monorepo README says t402 is an open standard for internet-native payments that aims to support all networks and forms of value, while remaining compatible with Tether WDK as the wallet layer
    • The package architecture published in the README shows t402 is broader than a simple client SDK: it includes core protocol types, many chain mechanisms, HTTP integrations, WDK modules, an A2A transport, mobile tooling, MCP tooling, and CLI utilities
    • The facilitator API docs say the public facilitator handles payment verification and onchain settlement, offers self-service API keys, usage tiers, and supported-network discovery, and can also be self-hosted for greater control and privacy
    • The self-hosted facilitator guide documents a production architecture with Redis-backed idempotency, Prometheus/Grafana monitoring, multi-chain RPC configuration, and operational concerns like rate limits and reverse-proxy deployment, which is a strong clue that t402 should be tracked as real payment infrastructure rather than only as a protocol spec
    • The AI-agent-payments guide says t402’s MCP integration lets agents pay for APIs and services autonomously with budget controls, multi-chain support, and integration into MCP-compatible assistant environments
    • The README advertises a canonical whitepaper, which reinforces that t402 is trying to present itself as a protocol-level standard rather than merely a collection of example middleware packages
  • Whitepaper: An official t402 whitepaper exists and was saved locally as ../whitepapers/t402-whitepaper.pdf; see also ../whitepapers/t402-primary-sources-2026-05-03.md.
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