Maximum on HTTP header values?

Website, Application, Performance
1

Is there an accepted maximum allowed size for HTTP headers? If so, what is it?

2

In practice you’re limited by server implementations. In Apache the default maximum is 8kb for the entire header, and I think nginx has the same default.

3 Likes
3

Just leaving this headere for addition to @i40west

Source: Maximum on HTTP header values? - Stack Overflow

  • Apache - 8K
  • Nginx - 4K-8K
  • IIS - 8K-16K
  • Tomcat - 8K – 48K
  • Node (<13) - 8K; (>13) - 16K

Depending on, if that question was related to Cloudflare. I found this doc for Workers: Limits · Cloudflare Workers docs

Request limits

URLs have a limit of 16 KB.
Request headers observe a total limit of 32 KB, but each header is limited to 16 KB.

4 Likes
4

Thank you so much!

5

>8k can trigger a 520:

6

If this is for pages then the max header length line is 1000 characters

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