Download websites that use gunicorn

About gunicorn

Gunicorn is rarely something a website owner decides to install. Written in Python and released under the MIT license in 2009, it exists to run WSGI applications behind a reverse proxy, and in a normal deployment the proxy in front of it is what answers the public internet. Gunicorn only becomes visible from outside when a response header, an error page or a misconfigured proxy lets the backend identify itself. Any list of sites running this server is therefore a list of sites where the backend leaked, not a census of Python deployments, and the real installed base is larger than anything a crawler can see.

The undercount is not a reason to ignore the signal. A leaked Gunicorn banner tells you the site is an application server rather than a content management system on shared hosting. Django, Flask and FastAPI projects sit behind it, which means an engineering team, a deploy pipeline and a dependency tree that somebody has to keep current. As of September 2026 we record gunicorn on 114,093 sites, and the interesting property of that population is who is in it: SaaS backends, internal tools that ended up exposed, data APIs and university systems rather than brochure sites.

Geography should be read with care here. Switzerland accounts for 80,306 of the detections and .ch leads the domain breakdown, a concentration far out of proportion to that country's share of the web. Skews of that size almost never reflect a national preference for a programming language. Concentrations like this come from one hosting company, one deployment image or one large customer whose fleet all answers the same way, and any analysis that treats the country column as a measure of developer taste will draw the wrong conclusion.

Version data adds the other half of the picture. We see 27 distinct versions in the field and the release recorded most often is 19.10.0, which is several generations behind what a current project would install. Version spread on a component like this reads as a maintenance signal rather than a feature signal, because the teams that pin an old worker server rarely keep the rest of the stack current either. Anyone sizing an exposure, planning an upgrade campaign or qualifying accounts by engineering maturity is really asking about that distribution, not about any single site.

A per-domain lookup answers whether one site runs Gunicorn. The downloadable list answers the questions that only exist in aggregate: how many sites on a given TLD or in a given market expose a Python backend, which hosting networks account for them, how the version distribution moves between snapshots, and which of those hosts also run something else worth knowing about. Security vendors use it to size a population, Python tooling and observability companies use it to find teams already committed to the ecosystem, and infrastructure sales teams use it to skip the shared-hosting long tail entirely. Filtering the Web servers data down to the Gunicorn column produces that working list in one pass, with the caveat still attached: everyone on it revealed their backend, and the ones who configured their proxy properly are missing.