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Content-Length

IANA permanent response RFC 9110 2 spellings

Declared by 62 providers across 1151 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.

Content-Lengthcontent-length

The registry

Status	permanent
Reference	RFC 9110, Section 8.6: HTTP Semantics

Providers declaring it (62)

aimlapi amazon-s3 apache-ozone argyle argyle-financial artifactory autodesk autodesk-fusion avito aws-s3 backblaze bird bitpowr-technologies-inc blindinsight chaitin cisco-webex cloudflare-r2 comet conekta cubefs deliverect didit ebay elbo-ai-inc engineering-platform extreme-networks filebase front github google hm-land-registry influxdata influxdb infobip insforge instabase lakefs lawvu lightroom linkedin london-stock-exchange-group microsoft-azure microsoft-azure-blob-storage nhost opik oracle oracle-cloud peertube pruna-ai sentinel-hub soracom streamelements turborepo userpilot usertesting vtex webex wikimedia wikipedia wispr-ai writer xflow

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