# jmacd/xdelta

open-source binary diff, delta/differential compression tools, VCDIFF/RFC 3284 delta compression

Repository: https://github.com/jmacd/xdelta
Canonical: https://ross.abutalabs.com/products/xdelta
Language: C
License Family: other
Last push: 2026-06-21T21:49:13+00:00

## Health v2 (maintenance only)
Score: 80/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 88, release rhythm 57, longevity 100
- inputs: {"age_days": 4180, "days_push": 73, "days_rel": 73, "gap_med": null, "n_releases_24m": 1}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1337, forks 217 (observed 2026-08-28T04:04:25.606444+00:00)

## What it is
Xdelta 3 is a C library and command-line tool for binary delta compression using the VCDIFF (RFC 3284) format. It computes compact differences between files and applies patches to reconstruct targets, with optional secondary compression via liblzma and BLAKE3 checksums.

## Use cases
- generate binary patches between file versions
- apply a delta patch to reconstruct a file
- reduce download size for software updates
- diff large binary files that text diff tools can't handle
- embed delta compression in a C application via the library

## When to choose
- you need standards-compliant VCDIFF/RFC 3284 delta streams
- you distribute binary updates and want minimal patch sizes
- you need a small, self-contained C library with no runtime dependencies

## When to avoid
- you need text-aware diffs or merges (use git or diff tools)
- you need cross-language bindings beyond C without extra work
- you need actively maintained multi-contributor development

## Facets
- artifact type: library
- maturity: stable
- function: compression, cli
- domain: files, developer-tools
- platform: windows, cross-platform, cli
- tags: binary-diff, delta-compression, vcdiff, rfc-3284, c-library, algorithms, linux, macos

## Member repositories
- jmacd/xdelta (main) score 80

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:25.606444+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 2026-08-30T04:44:03.149145+00:00, confidence not recorded.
  - readme: https://github.com/jmacd/xdelta (fetched 2026-08-28T04:04:25.606444+00:00, sha 7ba4dc6e6b6e)
- Data as of 2026-08-30T08:39:29.467469+00:00.