# Blosc/c-blosc

A blocking, shuffling and loss-less compression library that can be faster than `memcpy()`.

Repository: https://github.com/Blosc/c-blosc
Canonical: https://ross.abutalabs.com/products/c-blosc
Homepage: https://www.blosc.org
Language: C
License: NOASSERTION
License Family: other
Topics: c, compression, fast
Last push: 2025-12-15T01:03:00+00:00

## Health v2 (maintenance only)
Score: 48/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 57, release rhythm 8, longevity 100
- inputs: {"age_days": 5540, "days_push": 262, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- 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 1057, forks 172 (observed 2026-08-28T04:03:24.752674+00:00)

## What it is
C-Blosc is a high-performance, lossless compression library for binary data that uses blocking, shuffling, SIMD, and multi-threading to compress and decompress faster than memcpy(). It acts as a meta-compressor wrapping codecs like LZ4, Snappy, Zlib, and Zstandard. This original C-Blosc is in maintenance mode; C-Blosc2 is the actively developed successor.

## Use cases
- compress large binary datasets in memory or on disk
- speed up memory-bound computations with cache-fitting compression
- compress numerical arrays for scientific computing
- choose among multiple compression codecs via one API
- reduce memory bus traffic in data-intensive applications

## When to choose
- you need extremely fast lossless compression of binary/numerical data
- you want a single API over LZ4, Zstd, Zlib, Snappy, and BloscLZ
- you need a mature, widely used C library with SIMD and threading support

## When to avoid
- you are starting a new project - use C-Blosc2 instead, since this version gets no new features
- you need maximum compression ratio rather than speed
- you need compression of text or streaming data rather than fixed-size binary blocks

## Facets
- artifact type: library
- maturity: maintenance
- function: compression, serialization
- domain: performance, big-data, developer-tools
- platform: cross-platform, c, cpp, python
- tags: meta-compressor, simd, multithreaded, memory-bound, lossless, binary-data, cache-optimization

## Member repositories
- Blosc/c-blosc (main) score 48

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:24.752674+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 2026-08-30T06:57:54.006997+00:00, confidence not recorded.
  - readme: https://github.com/Blosc/c-blosc (fetched 2026-08-28T04:03:24.752674+00:00, sha 04c337397080)
  - homepage: https://www.blosc.org (fetched 2026-08-29T12:59:30.918182+00:00, sha 89c3e511b0e8)
- Data as of 2026-08-30T08:39:29.467469+00:00.