Ruff
Fast Python linter and code formatter written in Rust, made by Astral.
HN commenters like Ruff for fast Python linting and formatting in a single tool1234 and as a standard check that coding agents are told to run.56 Complaints are few: one commenter finds the CLI fragmented across ruff and uv,7 and another says agents get confused when ruff changes files outside their context.8
Why people recommend it
Speed · 3
Commenters say Ruff is much faster than older Python tools and can lint in seconds or less.
“Ruff can lint in seconds or even sub second.”
“I definitely appreciate a 16x speedup if possible.”
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“Ruff solved python formatting and linting.”
Linting and formatting · 3
One tool replaces black, pylint and similar tools, and commenters call it a default in their setups.
“Ruff solved python formatting and linting.”
“uv and ruff took over because they were in many ways simpler and much faster than the competition.”
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“Virtually every modern python developer uses an auto formatter today, and never needs to think about it (ruff, black).”
Sensible formatting · 3
It keeps commented items on their own lines and leaves intentional spacing alone.
“ruff sees your line comment and keeps each item on its line.”
“With agents it is helpful to make them run ruff and mypy to keep them honest”
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“Personally I love this rule because it saves me from looking at one extra commit”
Agent guardrails · 3
Commenters have coding agents run Ruff to keep generated code consistent.
“With agents it is helpful to make them run ruff and mypy to keep them honest”
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“I therefore build one (imperfectly, based on ruff lints), but it solved the problem entirely.”
Reusable crates · 2
Its Rust parser and AST crates are reused by other projects for their speed.
“I used rust 'cause of Ruff. They have an outstanding set of crates”
“Ruff's AST which is fast”
Code quality rules · 1
Newer rule sets caught issues that earlier versions missed.
“the new rules do improve code quality. It caught quite a few things previous versions didn't.”
Caveats and dissent
Fragmented CLI · 1
Ruff, ty and uv split commands awkwardly, and uv's format command gives different results.
“I love Astral’s tools, but I wonder why the CLI feels so fragmented.”
Agent context · 1
Running Ruff outside an agent's loop changes files and confuses the agent.
“I use ruff and my agents get confused if I edit and run ruff out of band.”
Often compared with
Who recommends it in their own words
Threads where it came up
- Ruff v0.16.0 – Significant new updates – 413 default rules up from 59 5 mentions
- Bringing uv and ty together 3 mentions
- SlopCodeBench 10/2026 – Opus 5.5, Astra wins overall, xhigh considered harmful 2 mentions
- Ask HN: What non-LLM tools have meaningfully improved your dev productivity? 2 mentions
- Functional State Machines in Rust: Typestate and Newtype Patterns 1 mention
- Mojo 1.0 Is Here 1 mention
Also written as ruff. Data: ruff.json. Quotes are verbatim; the verdict and theme labels are written by a model from these comments, and every clause links to its sources.
All comments 19
“I think Ruff is great”
“uv and ruff took over because they were in many ways simpler and much faster than the competition.”
“I love Astral’s tools, but I wonder why the CLI feels so fragmented.”
“With agents it is helpful to make them run ruff and mypy to keep them honest”
“I use ruff and my agents get confused if I edit and run ruff out of band.”
“I therefore build one (imperfectly, based on ruff lints), but it solved the problem entirely.”
“Virtually every modern python developer uses an auto formatter today, and never needs to think about it (ruff, black).”
“ruff sees your line comment and keeps each item on its line.”
“Ruff's AST which is fast”
“Personally I love this rule because it saves me from looking at one extra commit”
“Ruff can lint in seconds or even sub second.”
“the new rules do improve code quality. It caught quite a few things previous versions didn't.”
“or ruff in Python”
“I immediately set up up ruff, ty, pytest, pre-commit hook”
“big fan of uv and ruff and recently ty”
“Ruff solved python formatting and linting.”
“I definitely appreciate a 16x speedup if possible.”
“I used rust 'cause of Ruff. They have an outstanding set of crates”
“This newly-minted fanboy recommends you try out ty w/ uv & ruff!”