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T402Volume 02 · Specification
The Stablecoin
Payment Protocol
for the Internet.
An open HTTP-native payment protocol. Wire-compatible with x402, plus the authCapture + dispute layer and USDT-on-TRON. Compatible with Tether's open-source WDK. Built for AI agents.
- Networks
- 47
- Kinds
- 71
- SDKs
- TS · Go · Py · Java
- Protocol fees
- $0.00
- License
- Apache 2.0
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T402.01Mechanism
HTTP-native. Built into the internet.
T402 turns HTTP 402 “Payment Required” into a real protocol. The server signals payment terms in the response; the client replies with a signed stablecoin authorization on the next request. No WebSockets, no polling, no SDK lock-in.
HTTP/1.1 402 Payment Required
Content-Type: application/json
Payment-Required: ...
{
"scheme": "exact",
"network": "eip155:8453",
"maxAmountRequired": "1000000"
}
T402.02Features
A complete payment infrastructure
for the multi-chain future.
- 01
- HTTP Native
- Built into standard HTTP request-response cycles. No WebSockets, no polling, no additional infrastructure. Just add a header.
- 02
- Gasless (ERC-4337)
- Users pay zero gas fees. EIP-3009 permit signatures and account abstraction handle everything.
- 03
- Multi-Chain
- 47 networks across 12 blockchain families. EVM, Solana, TON, TRON, NEAR, Aptos, Tezos, Polkadot, Stacks, Cosmos, Stellar, and Bitcoin.
- 04
- AI Agent Ready
- MCP and A2A protocol support lets AI agents autonomously discover and pay for services.
- 05
- Open Source
- Fully open-source protocol. Self-host the facilitator, audit the code, build on top.
T402.03Colophon
Start building.
Open-source HTTP payment protocol. Wire-compatible with x402, plus authCapture, dispute, and USDT-on-TRON. Self-host the facilitator or use t402 Pay.
Apache 2.0x402-compatibleWDK-compatible