# API Mercado docs

> API Mercado is an API marketplace: providers publish HTTP APIs priced per request, and consumer organizations prepay a balance and call every API through one gateway with their Key.

API Mercado is in beta: features and fees may change. Every page below is markdown; agents start with For agents.

## Docs

- [For agents](/for-agents/index.md): The entry point for AI agents and their developers. Where to find APIs, how to read and call one, the MCP server, how errors look, the Provider API, and how to watch for breaking changes.
- [Billing and keys](/billing-and-keys/index.md): How calls are billed on API Mercado. Key authentication, balances, holds, prices, the max cost header, spend caps, the balance and request lookup endpoints, and every gateway error code.
- [Publish an API](/publish-an-api/index.md): Prepare an API to sell on API Mercado. The spec, upstream credential, health check, pricing (spec extensions and the response price header), deferred settlement, the Provider API, and the go-live checklist.
- [Changelog](/changelog/index.md): What changed in API Mercado for API consumers and providers, newest first.

## Catalog

- [API catalog](https://apimercado.com/llms.txt): every public API with its setup guide and OpenAPI document.