Async & Long-Running

Headers for work that does not finish inside the request: preference for async handling, polling locations, progress, retry timing.

5 headers

70 provider declarations

Header	Providers	Status
Prefer	37	permanent	regulated
Content-Location	19	permanent	regulated
Last-Event-ID	9	permanent
Preference-Applied	4	permanent
Status-URI	1	permanent

All categories

Authentication Authorization & Scope Caching Conditional Requests & Concurrency Content Negotiation Representation Metadata Connection & Transport CORS Security Policy Privacy & Consent Rate Limiting & Quota Tracing & Correlation Idempotency & Reliability Versioning & Lifecycle Integrity & Signing Async & Long-Running Cost & Metering Agent & Bot Identity

Work with this as data

Every header here is available over the APIs.io API and to AI agents over MCP. HTTP Headers is not yet its own endpoint on the v1 API. Reach it through catalog search and the tag graph, or the MCP server.

MCP server

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https://apis.io/mcp

Tools for http headers

3 MCP tools reach this

apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

All 92 tools →

Call it yourself

curl for this page

Search the catalog

curl "https://apis.io/api/v1/search?q=async&limit=10"

Everything under a tag

curl "https://apis.io/api/v1/tags/async"

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