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User-Agent

IANA permanent request RFC 9110 2 spellings

Declared by 71 providers across 8804 published specification files in the APIs.io network.

What this header is for, and how to use it →

A count here is providers whose published contract declares this header — not providers who send it. Response headers set at the edge rarely appear in an OpenAPI at all, so a low number can measure documentation practice rather than deployment.

Spelled 2 ways

HTTP field names are case-insensitive (RFC 9110 §5.1), so every spelling below is the same header on the wire. A contract is not the wire: generated clients key off the string, and a developer reading two of these sees two different headers.

User-Agentuser-agent

The registry

Status	permanent
Reference	RFC 9110, Section 10.1.5: HTTP Semantics

Providers declaring it (71)

affirm amplitude apifreaks-api-hub-for-developers balad-corp bazaarvoice brewpage bright-pattern brightcove button chargebee cliniko clover coinme contentstack contextdev decart deliverect depict depictai engineering-platform expedia-group figure figure-technology-solutions finos github gocardless have-i-been-pwned helika helpscout hevn-inc intercom ipgeolocation jira just-eat keap keycorp klarna koala-io leonardo-ai lightspeed-pos line mailgun microsoft-azure moloco mtn-group national-weather-service noaa noaa-gov okta paystack plausible podcastindex postman pydantic-ai ramp razorpay ringcentral sageox shutterstock small-improvements snowflake soveren spaitial-ai thingsboard todoist tollbit transmit-security ubuntu viator weather-gov worldpay

Explore

All headers Agent & Bot Identity Guidance on headers.apievangelist.com