# Surp

> Surp is a Base-native AI inference marketplace and x402 router.

## Key facts
- One OpenAI-compatible API: https://surp.ivc.lol/v1
- Live least-expensive-model routing across the Surplus Intelligence marketplace
- Exact-response caching for $0.001 cache hits
- Payments: x402, per-request EIP-3009 USDC authorization on Base (eip155:8453)
- No account needed for /v1/models; paid calls need an x402 signature or prepaid API key

## When to use Surp
- Use Surp when an agent needs OpenAI-compatible text inference with live model routing and transparent pricing.
- Use `surp/free` for zero-cost testing within the daily cap, `surp/value` for cost-aware production calls, and `surp/frontier` when quality matters most.
- Call POST https://surp.ivc.lol/v1/chat/completions with a prepaid Bearer key or fulfill the returned x402 payment challenge.
- Call GET https://surp.ivc.lol/v1/models before selecting a route or model.

## Developer resources
- Developer portal: https://surp.ivc.lol/developers
- API documentation: https://surp.ivc.lol/docs
- OpenAPI 3.1: https://surp.ivc.lol/openapi.json
- Authentication: https://surp.ivc.lol/auth.md
- MCP manifest: https://surp.ivc.lol/mcp.json
- MCP Server Card: https://surp.ivc.lol/.well-known/mcp/server-card.json
- A2A Agent Card: https://surp.ivc.lol/.well-known/agent-card.json
- Agent Skills: https://surp.ivc.lol/.well-known/agent-skills/index.json
- Self-serve API keys: https://surp.ivc.lol/app

## Docs
- API: https://surp.ivc.lol/docs
- Status: https://surp.ivc.lol/status
- Prices: https://surp.ivc.lol/prices
- About: https://surp.ivc.lol/about
- OpenAPI: https://surp.ivc.lol/openapi.json