# RE# regex engine

Hacker Approved page: https://hackerapproved.com/p/re-sharp-regex-engine/

5 people recommended RE# regex engine in Hacker News comments and 1 criticized it, November 2025 to October 2026. It was recommended in 1 of 12 months, in 2 threads. It does not meet the Hacker Approved badge rule.

5 of the 5 people who recommend it commented in one thread, “RE#: how we built the fastest regex engine in F#”.

**Verdict:** People recommend RE# for fast matching with intersection, complement and unbounded lookarounds, and call its extended operators a real improvement over existing engines.

Summary written by Claude from 9 comments.

## Why people recommend it

- Intersection and complement operators (2 comments in the sample): "even just the extended operators alone are a nice improvement over existing regex engines" ([source](https://news.ycombinator.com/item?id=47246502)) "it's very much faster and much easier to use (with intersection and complement" ([source](https://news.ycombinator.com/item?id=47248228))
- Fast on lookarounds and large patterns (2 comments in the sample): "Unbounded lookarounds without performance penalty at search time are an exciting  feature too." ([source](https://news.ycombinator.com/item?id=47246340)) "it's the fastest for large patterns and lookarounds" ([source](https://news.ycombinator.com/item?id=47246990))

## What people recommend instead

- [regex crate for Rust](https://hackerapproved.com/p/regex/): 8 recommend, 0 mixed, 3 criticize

## The badge

A product earns the Hacker Approved badge when at least 10 people recommend it, recommenders outnumber critics at least 2 to 1 (mixed feelings count toward neither side), it was recommended in at least 4 of the 12 months and in at least 5 different threads, and no single thread supplies more than half of the people who recommend it. Health and money products are never badged.

## Cite as

Hacker Approved, "RE# regex engine", https://hackerapproved.com/p/re-sharp-regex-engine/ (5 recommend, 0 mixed, 1 criticize; Hacker News comments, November 2025 to October 2026).

Counts updated 2 Nov 2026, with data through October 31, 2026.