# Uvicorn 0.52.0 — Version 0.52.0

- Product: Uvicorn (https://whatsnew.fyi/product/uvicorn)
- Vendor: Encode
- Date: 2026-07-29
- Version: 0.52.0
- Original notes: https://github.com/Kludex/uvicorn/releases/tag/0.52.0
- Permalink: https://whatsnew.fyi/product/uvicorn/releases/0.52.0

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **added** — Add an experimental zttp HTTP/1.1 implementation, selectable with --http zttp
- **fixed** — Keep non-ASCII WebSocket request headers intact with websockets 17.0, which encodes them with ISO-8859-1

This release adds an experimental HTTP/1.1 implementation backed by [zttp](https://zttp.marcelotryle.com/), a sans-IO HTTP parser I've been developing on the side: a core written in Zig, with bindings to Python. It has been running under a fuzzer for some weeks now, and has been through multiple rounds of security auditing.

It is still **experimental**, so don't put it in front of production traffic yet. Try it with `--http zttp`, and please send any feedback to the [issue tracker](https://github.com/Kludex/uvicorn/issues).

###### Added

* Add an experimental `zttp` HTTP/1.1 implementation, selectable with `--http zttp` (#2979)

###### Fixed

* Keep non-ASCII WebSocket request headers intact with websockets 17.0, which encodes them with ISO-8859-1 (#3036)


**Full Changelog**: https://github.com/Kludex/uvicorn/compare/0.51.0...0.52.0