Documentation

A decentralized exchange for LLM inference. Sellers compete on price, buyers get the cheapest rate, and everything settles on-chain via USDC on Base.

Quickstart API Reference

What is this?

Surplus Intelligence is a two-sided marketplace for AI inference. Think of it as a stock exchange, but for API calls to AI models.

Buyers get one API key and one base URL. Call it like OpenAI — the marketplace routes to the cheapest available seller.
Sellers list any OpenAI-compatible endpoint, set their own price, and earn USDC on every request they serve.
Settlement is on-chain on Base — transparent, non-custodial, and verifiable by anyone.

Choose your path

Three ways in

Buyer
API key, prepaid balance
Agent
x402, no account at all
Seller
Lists the offers the other two consume

Buyers and agents differ only in how they pay. Sellers come at the same order book from the other side — the offers buyers are routed to.

Buyer Quickstart

Sign in, get an API key, and make your first request in 2 minutes — works with Cursor, Aider, and any OpenAI-compatible tool.

Seller Quickstart

List your API endpoint, set your own prices, and earn USDC per request.

Agent Quickstart

Build autonomous agents that pay per-request via x402 — no account needed.

Claude Code (Anthropic Skin)

Point Claude Code or the Anthropic SDK at the marketplace — on any model, not just Claude.

Cursor Setup

Point Cursor at the marketplace with one base-URL change.

OpenCode / Aider

Use the marketplace from OpenCode, Aider, and other CLI coding tools.

BYOK Priority Provider

Bring your own provider key and have your requests routed to it first.

Wallet Funding

Fund your wallet with USDC on Base — on-chain, by card, or with credits.

Media Inputs

Send an image, document, or audio file to a model, and what the marketplace does with it.

API Reference

Full endpoint documentation for the OpenAI-compatible surface and the marketplace APIs.

Security & Privacy

Seller key handling, logging, deletion, limits, and current trust assumptions.

Payments

Deposited USDC credits, fiat credits, and x402 for agents.

Changelog

What changed in the marketplace and the API surface.

llms.txt — for LLMs & agents

A markdown guide to the marketplace written for LLMs and agents — base URL, endpoints, payment rails, and contracts.

Open llms.txt

Current snapshot

These numbers change as the live model registry and seller order book change. Treat the APIs as the source of truth.

GET /v1/models returns the full catalog — text, vision, image, audio/music, video, TTS/STT and embedding models.
GET /api/marketplace returns how many of those currently have live seller offers. Both counts move with seller liquidity, so query the endpoints rather than trusting a number printed here.
GET /v1/prices tracks pricing across many provider pricing sources.
The seller allowlist covers 26+ provider hosts plus every regional Bedrock host; GET /v1/providers is the live list. Seller liquidity is not spread evenly across them.
OpenAI-compatible — works with Cursor, Aider, OpenCode, Continue, and any tool that speaks /v1/chat/completions.
Anthropic-compatible — an "Anthropic skin" at /anthropic lets Claude Code and the Anthropic SDK route through the marketplace (on any model, not just Claude).
Two ways to fund — deposited USDC credits or fiat credits, plus x402 for per-request agent payments.

Canonical base URL: https://api.surplusintelligence.ai/v1