> Part of the API Mercado docs, in beta. Markdown for every page: append `index.md` to its URL. Site map: /llms.txt

# API Mercado docs

API Mercado is an API marketplace. Providers publish HTTP APIs priced per
request; consumer organizations prepay a balance and call every API through one
gateway with their Key. The catalog is at [apimercado.com](https://apimercado.com).

API Mercado is in beta: features and fees may change. The [Changelog](/changelog/)
lists every Release.

## Call APIs

- [Authenticate a request](/billing-and-keys/#authenticating-requests): send your Key, or call keyless operations.
- [What each call costs](/billing-and-keys/#what-is-charged): prices, holds and balances.
- [Spend caps](/billing-and-keys/#spend-caps): limit what one Key can spend.
- [Error codes](/billing-and-keys/#error-codes): every gateway error and how to fix it.

## Sell APIs

- [Publish an API](/publish-an-api/): from the OpenAPI spec to the go-live checklist.
- [Pricing](/publish-an-api/#4-pricing): set a price and a cap per operation, in your spec.
- [Deferred settlement](/publish-an-api/#5-deferred-settlement): charge after a long-running job finishes.
- [Provider API](/publish-an-api/#6-provider-api): refresh your spec from CI.

## Build with agents

- [For agents](/for-agents/): the reference an AI agent reads first.
- [MCP server](/for-agents/#mcp-server): search and read the catalog from your agent.
- [llms.txt](/llms.txt): the site map as markdown.