# ruff 0.16.5

- Product: ruff (https://whatsnew.fyi/product/ruff)
- Vendor: ruff
- Date: 2026-08-27
- Version: 0.16.5
- Original notes: https://github.com/astral-sh/ruff/releases/tag/0.16.5
- Permalink: https://whatsnew.fyi/product/ruff/releases/0.16.5

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'.

---

- **added** — Allow rules without codes
- **added** — Introduce category selectors
- **changed** — Update preview default rules and categories
- **fixed** — Detect blocking generic HTTP requests (ASYNC210)
- **fixed** — Allow timezone-safe strptime chains (DTZ007)
- **fixed** — Respect side effects in lambda defaults (SIM401)
- **fixed** — Fix duplicated "of" in ClientOptions doc comment

##### Release Notes

Released on 2026-08-27.

###### Preview features

- Allow rules without codes ([#28049](https://github.com/astral-sh/ruff/pull/28049))
- Introduce category selectors ([#27666](https://github.com/astral-sh/ruff/pull/27666))
- Update preview default rules and categories ([#27877](https://github.com/astral-sh/ruff/pull/27877))

###### Bug fixes

- \[`flake8-async`\] Detect blocking generic HTTP requests (`ASYNC210`) ([#28024](https://github.com/astral-sh/ruff/pull/28024))
- \[`flake8-datetimez`\] Allow timezone-safe `strptime` chains (`DTZ007`) ([#28023](https://github.com/astral-sh/ruff/pull/28023))
- \[`flake8-simplify`\] Respect side effects in `lambda` defaults (`SIM401`) ([#28000](https://github.com/astral-sh/ruff/pull/28000))

###### Server

- Fix duplicated "of" in `ClientOptions` doc comment ([#27978](https://github.com/astral-sh/ruff/pull/27978))

###### Documentation

- Document rule acceptance guidelines ([#27910](https://github.com/astral-sh/ruff/pull/27910))
- Document the new category selectors ([#27906](https://github.com/astral-sh/ruff/pull/27906))

###### Contributors

- [@AlexWaygood](https://github.com/AlexWaygood)
- [@sharkdp](https://github.com/sharkdp)
- [@jelle-openai](https://github.com/jelle-openai)
- [@charliermarsh](https://github.com/charliermarsh)
- [@ntBre](https://github.com/ntBre)
- [@aarushkandukoori](https://github.com/aarushkandukoori)

##### Install ruff 0.16.5

###### Install prebuilt binaries via shell script

```sh
curl --proto '=https' --tlsv1.2 -LsSf https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-installer.sh | sh
```

###### Install prebuilt binaries via powershell script

```sh
powershell -ExecutionPolicy Bypass -c "irm https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-installer.ps1 | iex"
```

##### Download ruff 0.16.5

|  File  | Platform | Checksum |
|--------|----------|----------|
| [ruff-aarch64-apple-darwin.tar.gz](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-aarch64-apple-darwin.tar.gz) | Apple Silicon macOS | [checksum](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-aarch64-apple-darwin.tar.gz.sha256) |
| [ruff-x86_64-apple-darwin.tar.gz](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-x86_64-apple-darwin.tar.gz) | Intel macOS | [checksum](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-x86_64-apple-darwin.tar.gz.sha256) |
| [ruff-aarch64-pc-windows-msvc.zip](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-aarch64-pc-windows-msvc.zip) | ARM64 Windows | [checksum](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-aarch64-pc-windows-msvc.zip.sha256) |
| [ruff-i686-pc-windows-msvc.zip](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-i686-pc-windows-msvc.zip) | x86 Windows | [checksum](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-i686-pc-windows-msvc.zip.sha256) |
| [ruff-x86_64-pc-windows-msvc.zip](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-x86_64-pc-windows-msvc.zip) | x64 Windows | [checksum](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-x86_64-pc-windows-msvc.zip.sha256) |
| [ruff-aarch64-unknown-linux-gnu.tar.gz](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-aarch64-unknown-linux-gnu.tar.gz) | ARM64 Linux | [checksum](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-aarch64-unknown-linux-gnu.tar.gz.sha256) |
| [ruff-i686-unknown-linux-gnu.tar.gz](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-i686-unknown-linux-gnu.tar.gz) | x86 Linux | [checksum](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-i686-unknown-linux-gnu.tar.gz.sha256) |
| [ruff-powerpc64-unknown-linux-gnu.tar.gz](https://releases.astral.sh/github/ruff/releases/download/0.16.5/ruff-powerpc64-unknown-linux-gnu.tar.gz) | PPC64 Linux | [checksum](https:/

_[Truncated at 4000 characters — full notes: https://github.com/astral-sh/ruff/releases/tag/0.16.5]_