# dlclark/regexp2

A full-featured regex engine in pure Go based on the .NET engine

Repository: https://github.com/dlclark/regexp2
Canonical: https://ross.abutalabs.com/products/regexp2
Language: Go
License: MIT
License Family: permissive
Topics: regex-engine, regexp, regex, regular-expression, regular-expression-engine, go
Last push: 2026-08-15T02:28:14+00:00

## Health v2 (maintenance only)
Score: 76/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 97, release rhythm 35, longevity 100
- inputs: {"age_days": 3898, "days_push": 19, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1183, forks 95 (observed 2026-08-28T04:03:54.437850+00:00)

## What it is
A full-featured regular expression engine for Go, ported from the .NET regex engine. It supports backtracking and Perl5/.NET-compatible patterns, trading the built-in regexp package's constant-time guarantees for expressive power.

## Use cases
- use complex regex patterns with backtracking in Go
- match .NET-compatible regular expressions in Go
- use Perl5 regex features not supported by Go's regexp package
- split strings with regex matches in Go
- migrate .NET regex patterns to a Go application

## When to choose
- you need backtracking, lookarounds, or other advanced regex features RE2 lacks
- you need pattern compatibility with .NET or Perl5
- you're porting code that relies on .NET regex semantics

## When to avoid
- you need constant-time matching guarantees against catastrophic backtracking (use Go's built-in regexp/RE2)
- your patterns are simple and well-served by the standard library
- you're processing untrusted input where regex DoS is a concern

## Facets
- artifact type: library
- maturity: active
- function: parser
- domain: developer-tools, parsers
- platform: go, cross-platform
- tags: regex-engine, backtracking, dotnet-compatible, perl5-regex, text-processing

## Member repositories
- dlclark/regexp2 (main) score 76

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:54.437850+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:24:33.381978+00:00, confidence not recorded.
  - readme: https://github.com/dlclark/regexp2 (fetched 2026-08-28T04:03:54.437850+00:00, sha d5f701c4bd92)
- Data as of 2026-08-30T08:39:29.467469+00:00.