# facebookincubator/fastmod

A fast partial replacement for the codemod tool. Assists with large-scale codebase refactors via regex-based find and replace with human oversight and occasional intervention.

Repository: https://github.com/facebookincubator/fastmod
Canonical: https://ross.abutalabs.com/products/fastmod
Language: Rust
License: Apache-2.0
License Family: permissive
Topics: cli, command-line, command-line-tool, find-and-replace, rust, replace
Last push: 2026-07-28T17:37:32+00:00

## Health v2 (maintenance only)
Score: 65/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 94, release rhythm 8, longevity 100
- inputs: {"age_days": 3061, "days_push": 36, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1923, forks 55 (observed 2026-08-28T04:05:55.297778+00:00)

## What it is
fastmod is a fast, Rust-based partial replacement for the codemod tool that assists with large-scale codebase refactors via regex-based find and replace. It emphasizes an interactive workflow where users verify their regex with colored diffs before applying replacements everywhere, with options to accept, reject, or edit each change.

## Use cases
- find and replace across an entire codebase with regex
- interactively review and apply bulk code refactors
- deprecate an API or HTML tag across many files
- apply a verified regex replacement everywhere in a large repo
- rewrite patterns across files with per-match accept/reject/edit control

## When to choose
- you want codemod-like interactive find-and-replace with much better performance
- you need to verify a regex interactively then apply it across a whole codebase
- you want fast parallel directory traversal for bulk edits

## When to avoid
- you rely on codemod's --start, --end, or --count options
- you need codemod's Python API or programmatic integration
- your regexes require lookaround or backreferences (Rust regex syntax differs)

## Facets
- artifact type: cli-tool
- maturity: active
- function: developer-tools, cli, search-engine
- domain: developer-tools, version-control
- platform: windows, cli, rust
- tags: codemod, find-and-replace, refactoring, regex, bulk-editing, command-line, linux, macos

## Member repositories
- facebookincubator/fastmod (main) score 65

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:55.297778+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 2026-08-30T03:09:38.042804+00:00, confidence not recorded.
  - readme: https://github.com/facebookincubator/fastmod (fetched 2026-08-28T04:05:55.297778+00:00, sha 737c4151f5cf)
  - registry_crates: https://crates.io/api/v1/crates/fastmod (fetched 2026-08-29T10:48:56.644359+00:00, sha ef519d4deede)
- Data as of 2026-08-30T08:39:29.467469+00:00.