2026-09-02: nginx-1.31.5 mainline version has been released, featuring control API, predicate locations, and the ngx_http_json_module.
I cannot find documentation on what ngx_http_json_module does. Can someone please clarify?
Hi there,
I suspect that the main nginx.org site has not yet updated to the newest-of-the-new version, so the docs aren’t yet in “the usual place”. I’m sure they will be added when the time is right.
So until then, probably the best way to early-investigate is “Read The Fine Source” – for new things in 1.31.5, that would be at something like Comparing release-1.31.4...release-1.31.5 · nginx/nginx · GitHub
From that, the relevant-looking things seem to be from August 24; and in that list, “Added the json parser module” is “commit a1f4a61”, with the commit message and details at Added the json parser module · nginx/nginx@a1f4a61 · GitHub
The commit message does summarise the intention, in a way that is (probably) much clearer than the plain 900-line .c file 
In short – if you start with some json, you can “json_set” a new nginx variable with a specific value parsed from the json.
Having access to the source, and the change history, is great for seeing what is actually happening, even if the “friendly” documentation is not yet published (and especially since the “friendly” documentation can only ever summarise what the code is actually doing).
Cheers,
Yeah, docs got a little behind, being sorted as we speak! Thanks for your patience.
Docs are here.