2s — pay-per-call API for AI agents

# 2s > Unified JSON REST API for AI agents — an ever-expanding catalog of endpoints, pay per call in USDC on Base or Solana via x402. No accounts, no API keys, no monthly fees — just a USDC-funded wallet on either chain. Open-ended experiment in maximally-comprehensive agent infrastructure. ## How it works 1. Call any endpoint with no auth → receive `402 Payment Required` with the x402 PaymentRequirements envelope. The `accepts` array lists every supported settlement rail. 2. Sign for the chain you hold USDC on: - **Base**: sign an `EIP-3009 transferWithAuthorization` from your EVM wallet. - **Solana**: sign a partial SPL token transfer transaction from your Solana wallet. 3. Retry the call with the base64-encoded payload in the `PAYMENT-SIGNATURE` header (or `X-PAYMENT` for v1 clients) → receive `200 OK` plus an `X-PAYMENT-TX` header pointing at the on-chain settlement. Gas / transaction fees are paid by the facilitator. The caller only needs USDC. ## Machine-readable resources - [https://2s.io/api/directory](https://2s.io/api/directory) — endpoint catalog (JSON) - [https://2s.io/api/openapi](https://2s.io/api/openapi) — OpenAPI 3.1 spec - [https://2s.io/.well-known/x402](https://2s.io/.well-known/x402) — x402 service manifest - [https://2s.io/.well-known/mcp/server-card.json](https://2s.io/.well-known/mcp/server-card.json) — MCP server card (SEP-1649) - [https://2s.io/.well-known/ai-plugin.json](https://2s.io/.well-known/ai-plugin.json) — AI plugin manifest - [https://x402.org](https://x402.org) — protocol spec ## SDKs - TypeScript: `npm i @2sio/sdk` — <https://www.npmjs.com/package/@2sio/sdk> - Python: `pip install 2sio` — <https://pypi.org/project/2sio/> - MCP server: `npx -y @2sio/mcp` — <https://www.npmjs.com/package/@2sio/mcp> - Source + examples: <https://github.com/2s-io/sdk> ## Settlement - Network: `base` - Asset: USDC (`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`) - Treasury: `0x2b6D4988Db4723E6908Db86Ab2b8dFBc51