# google/zopfli

Zopfli Compression Algorithm is a compression library programmed in C to perform very good, but slow, deflate or zlib compression.

Repository: https://github.com/google/zopfli
Canonical: https://ross.abutalabs.com/products/zopfli
Language: C++
License: Apache-2.0
License Family: permissive
Archived: true
Last push: 2024-08-10T16:45:24+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 4195, "days_push": 753, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3595, forks 353 (observed 2026-08-28T04:08:11.330727+00:00)

## What it is
Zopfli is a C library implementing a compression algorithm that produces highly optimized, deflate-compatible output (deflate, zlib, and gzip formats) at the cost of slow compression speed. It includes a command-line binary for creating very well-compressed gzip files, and only compresses—decompression uses standard zlib tools.

## Use cases
- compress static web assets to the smallest possible gzip size
- pre-compress files for serving with gzip_static
- reduce size of embedded firmware or data blobs with deflate
- create maximally compressed zip/gzip archives offline
- optimize PNG-like deflate streams for smaller payloads

## When to choose
- compression ratio matters more than compression speed
- output must remain compatible with standard zlib/deflate decompressors
- compressing static assets once and serving many times

## When to avoid
- you need fast, real-time compression
- you need decompression functionality (Zopfli only compresses)
- streaming or incremental compression is required

## Facets
- artifact type: library
- maturity: maintenance
- function: compression
- domain: files, developer-tools, performance
- platform: windows, cross-platform, cli
- tags: deflate, gzip, zlib, c-library, lossless-compression, linux, macos

## Member repositories
- google/zopfli (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:11.330727+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 2026-08-29T18:33:48.128587+00:00, confidence not recorded.
  - readme: https://github.com/google/zopfli (fetched 2026-08-28T04:08:11.330727+00:00, sha 436a47ad1829)
- Data as of 2026-08-30T08:39:29.467469+00:00.