About RFC Lookup

Search 25+ foundational RFCs by number, title, or topic. Part of the DevTools Surf developer suite. Browse more tools in the Networking collection.

Use Cases

• Reference the canonical spec when designing protocols
• Cite the right RFC in design docs and PR descriptions
• Refresh on HTTP/TLS/OAuth specs by topic
• Quote the RFC verbatim in public specs or standards conversations

Tips

• Search by number (e.g. 9110) or topic (e.g. http)
• All RFCs link directly to rfc-editor.org
• Includes only the core RFCs still in force

Fun Facts

• The first RFC, RFC 1 'Host Software' was published on April 7, 1969 by Steve Crocker — before ARPANET even had two nodes connected.
• RFC 2324 'Hyper Text Coffee Pot Control Protocol' (HTCPCP) is an April Fools' joke that defined HTTP status code 418 'I'm a teapot' — which is now implemented in most web frameworks.
• There are over 9,500 published RFCs as of 2024. They are never updated in place — a new RFC is published to obsolete or update an existing one.

FAQ

Which RFCs are indexed?

25+ foundational ones covering HTTP, TCP/IP, DNS, SMTP, TLS, OAuth. The RFCs developers actually reference, not every 10,000+ RFC ever published.

Can I read the full RFC?

Links to the IETF source (datatracker.ietf.org). The tool surfaces titles, dates, topics, and one-line summaries; the full text is at the linked source.

How do I cite an RFC?

Standard format: `[RFC 7231]` for HTTP semantics. Some places use `RFC-7231`. The tool shows the canonical citation format.

Are obsolete RFCs marked?

Yes — if an RFC has been superseded (e.g., RFC 2616 by 7230-7237), the tool shows which newer RFC replaced it.