Authentication

Headers that carry who the caller is — credentials, tokens, keys, signatures of identity. The most declared category in the catalog and the most inconsistently spelled.

44 headers

3528 provider declarations

Header	Providers	Status
Authorization	1382	permanent
x-api-key	798	de-facto
X-Amz-Content-Sha256	98	de-facto
X-Amz-Date	98	de-facto
X-Amz-Security-Token	97	de-facto
X-Amz-Algorithm	96	de-facto
X-Amz-Credential	96	de-facto
X-Amz-Signature	96	de-facto
X-Amz-SignedHeaders	96	de-facto
apikey	94	de-facto
api-key	93	de-facto
x-fapi-auth-date	90	de-facto	regulated
x-client-id	53	de-facto
key	52	de-facto
Set-Cookie	51	permanent	regulated
token	46	de-facto
api_key	46	de-facto
X-Auth-Token	44	de-facto
WWW-Authenticate	43	permanent
Ocp-Apim-Subscription-Key	38	de-facto
Cookie	15	permanent
x-fapi-customer-last-logged-time	4	vendor	regulated
Set-Cookie2	1	obsoleted
DPoP	1	permanent	regulated
Authentication-Control	—	permanent
Cert-Not-After	—	permanent
Cert-Not-Before	—	permanent
Client-Cert	—	permanent
Client-Cert-Chain	—	permanent
Concealed-Auth-Export	—	permanent
Cookie2	—	obsoleted
CTA-Common-Access-Token	—	provisional
DPoP-Nonce	—	permanent
Hobareg	—	permanent
Include-Referred-Token-Binding-ID	—	permanent
Lock-Token	—	permanent
Optional-WWW-Authenticate	—	permanent
OSCORE	—	permanent
Proxy-Authenticate	—	permanent
Proxy-Authentication-Info	—	permanent
Proxy-Authorization	—	permanent
Sec-Token-Binding	—	permanent
Security-Scheme	—	obsoleted
Authentication-Info	—	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

One button, every client — Claude, Cursor, VS Code and the rest.

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=authentication&limit=10"

Everything under a tag

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

Discovery needs no key. Ratings and market analysis are Pro.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

GitHub Google LinkedIn

A second provider on the same verified email joins the account you already have.