httplint 2026.2.3

Lint for HTTP messages.

httplint

This Python library lints HTTP messages; it checks them for correctness and reports any issues it finds. httplint can report on 237 different aspects of your HTTP message, including checks against 164 header fields.

It performs all message-level checks for REDbot, but does not perform any 'active' checks by making requests to the network, and it does not have a Web user interface.

Using httplint as a Library

httplint exposes two classes for linting: HttpRequestLinter and HttpResponseLinter. They expose the following methods for telling the linter about the HTTP message:

• As appropriate:
  • process_request_topline, which takes three bytes arguments: method, uri, and version
  • process_response_topline, which takes three bytes arguments: version, status_code, and status_phrase
• process_headers for the headers, taking a list of (name, value) tuples (both bytes)
• feed_content for the body (which can be called zero to many times), taking an inbytes argument
• finish_content when done, which has two arguments; a bool indicating whether the response was complete, and an optional list of tuples for the trailers, in the same format that process_headers takes.

For example:

from httplint import HttpResponseLinter

linter = HttpResponseLinter()
linter.process_response_topline(b'HTTP/1.1', b'200', b'OK')
linter.process_headers([
  (b'Content-Type', b'text/plain'),
  (b'Content-Length', b'10'),
  (b'Cache-Control', b'max-age=60')
])
linter.feed_content(b'12345')
linter.feed_content(b'67890')
linter.finish_content(True)

You can also enable no_content mode if you do not have the message body, or do not wish to check it:

linter = HttpResponseLinter(no_content=True)

Using httplint from the Command Line

httplint can also be used from the command line. For example:

> curl -s -i --raw https://www.mnot.net/ | httplint -n
* The Content-Length header is correct.
* The resource last changed 8 days 6 hr ago.
* This response allows all caches to store it.
* The server's clock is correct.
* This response is fresh until 3 hr from now.
* This response may still be served by a cache once it becomes stale.

Interpreting Notes

Once a message has been linted, the results will appear on the notes property. This is a list of Note objects, each having the following attributes:

• category - the Note's category; see note.categories
• level - see note.levels
• summary - a brief, one-line description of the note
• detail - a longer explanation
• subnotes - a list of child Note objects

Note that summary is textual, and needs to be escaped in a markup environment; detail, however, is already escaped HTML.

Continuing our example:

for note in linter.notes:
  print(note.summary)

and the output should be:

The Content-Length header is correct.
This response allows all caches to store it.
This response doesn't have a Date header.
This response is fresh until 1 min from now.
This response may still be served by a cache once it becomes stale.

Field Descriptions

The description of any field can be found by calling get_field_description. For example:

>>> from httplint import get_field_description
>>> get_field_description("Allow")
'The `Allow` response header advertises the set of methods that are supported by the resource.'

If a description cannot be found it will return None.