HTTP Referer: the typo the standard keeps

Open RFC 9110 (June 2022), section 10.1.3. The field is written as Referer [sic], and the text says plainly that the field name is misspelled. The word it means is referrer.

Check yourself

Should a new client send Referrer: to be correct? Answer: no. The field the standard defines is Referer, so that's the name to send and to read.

Example

Illustrative. A log parser looks for 1 header, correctly spelled. Every row comes back empty, and 2 people spend a morning on it. One note in the weekly report saves the next person the same morning.

Important

The same section says a user agent must not include the fragment and userinfo parts of the URI in this field. Worth a look when you log or forward it.

Small things worth logging

• ☐ Odd names you must keep
• ☐ Workarounds and why they exist
• ☐ Who to ask about them
• ☐ When to look again

Weekly status report — note the small stuff →

Source: rfc-editor.org, RFC 9110, section 10.1.3.