# Pyrefly

28 Hacker News commenters recommended Pyrefly and 8 criticized it, November 2025 to November 2026. It was recommended in 8 of 13 months; owners who said how long report a median of 0.003 years (3 owners). It meets the Hacker Approved badge rule.

**Verdict:** People recommend it for speed, low memory use and strict type checking. Main caveat: its editor extension can change config files without asking.

## Why people recommend it

- Faster than other checkers (6 comments): "we are quite a bit faster than pyright (almost 10x avg) and use far less memory (almost half)" ([source](https://news.ycombinator.com/item?id=48148937)) "rust-based tools (ty, pyrefly) have popped up, running sub-second." ([source](https://news.ycombinator.com/item?id=48428736)) "The reason I prefer pyrefly over mypy is mostly because of speed." ([source](https://news.ycombinator.com/item?id=47409333))
- Works well with uv and ruff (3 comments): "with that combination, has roughly the same agent ergonomics as Go and lower token count due to higher abstraction level" ([source](https://news.ycombinator.com/item?id=48828804)) "Python has uv, ruff and Pyrefly, and with that combination, has roughly the same agent ergonomics as Go" ([source](https://news.ycombinator.com/item?id=48828986)) "UV, Ruff and Pyrefy and you're set" ([source](https://news.ycombinator.com/item?id=48870377))
- Has the features people want (3 comments): "the Pyrefly implementation seems to have everything I'd like" ([source](https://news.ycombinator.com/item?id=48128109)) "pyrefly has everything and is faster than ty" ([source](https://news.ycombinator.com/item?id=50226948)) "everything I wanted from ty" ([source](https://news.ycombinator.com/item?id=50222870))
- Strong type checking (2 comments): "Pyrefly has much better checks IME (at least with strict mode)" ([source](https://news.ycombinator.com/item?id=50220285)) "purely on a type checking front, it's excellent" ([source](https://news.ycombinator.com/item?id=50221672))

## What people warn about

- Crash bugs in some releases (2 comments): "I've been using Pyrefly and loving it compared to Pyright, but they recently shipped some updates with crash bugs" ([source](https://news.ycombinator.com/item?id=46300812)) "they recently shipped some updates with crash bugs that forced me to pin to a previous version" ([source](https://news.ycombinator.com/item?id=46295074))
- Changes settings without asking (4 comments): "it should definitely be documented and undone on uninstall but the action itself is reasonable" ([source](https://news.ycombinator.com/item?id=47988490)) "Writing to global settings and leaving the mess behind after uninstall is not the same thing." ([source](https://news.ycombinator.com/item?id=47989145)) "Could they not gate this behind a notification on install?" ([source](https://news.ycombinator.com/item?id=47988390))
- Can use a lot of memory (2 comments): "It’s a memory hog! The other day it was using 2.5GB of RAM." ([source](https://news.ycombinator.com/item?id=48126536)) "It's a huge memory hog. The other day it was using 2.5GB!" ([source](https://news.ycombinator.com/item?id=48126504))

## Alternatives hackers recommend

- [ty Python type checker](https://hackerapproved.com/p/ty.md): 74 recommend
- [mypy](https://hackerapproved.com/p/mypy.md): 34 recommend
- [Pyright](https://hackerapproved.com/p/pyright.md): 31 recommend
- [basedpyright](https://hackerapproved.com/p/basedpyright.md): 9 recommend
- [Zuban](https://hackerapproved.com/p/zuban.md): 8 recommend

## Cite as

Hacker Approved, "Pyrefly", https://hackerapproved.com/p/pyrefly/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).