zlib
Shares rank 12 of 14 compression tools by recommenders
Free compression library people pick because it is built into most platforms and standard libraries. Caveat: it approaches a sequence's entropy slowly.
Free compression library people pick because it is built into most platforms and standard libraries. Caveat: it approaches a sequence's entropy slowly.
6 people gave an opinion
- recommend it
- 6
- criticize it
- 0
- approval share
- 100%
Recommended in 5 of 13 months
- November 2025: not recommended
- December 2025: not recommended
- January 2026: not recommended
- February 2026: recommended
- March 2026: recommended
- April 2026: not recommended
- May 2026: recommended
- June 2026: not recommended
- July 2026: recommended
- August 2026: not recommended
- September 2026: recommended
- October 2026: not recommended
- November 2026: not recommended (month in progress)
Why it doesn’t carry the badge
- 6 people recommend itNeeds 10 or more, not met.
- Nobody criticizes itNeeds 2 to 1 or better, met.
- Recommended in 5 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Fast and small implementation
“on my machine, it's about 10x faster to use zlib”
Comment from 12 Feb 2026 in “Text classification with Python 3.14's ZSTD module” “the inflate algorithm is tiny”
Comment from 16 Jul 2026 in “Optimizing Lua string literals to save 400 bytes”
What people warn about
Each mark is one comment
Slow to approach sequence entropy
“Zlib is an universal compressor but does not converge to the entropy of a sequence very fast.”
Comment from 29 May 2026 in “The Secret Garden of Rock-Paper-Scissors”
Other compression tools people recommend
The four most recommended other compression tools, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
| Product | Recommend | Criticize | Approval | Months | Owned | Badge |
|---|---|---|---|---|---|---|
| Zstandard (zstd) | 111 | 14 | 89% | 12 | — | Approved |
| Brotli | 24 | 18 | 57% | 7 | — | — |
| gzip | 23 | 13 | 64% | 8 | — | — |
| tar | 19 | 13 | 59% | 11 | — | — |
| zlibThis page | 6 | 0 | 100% | 5 | — | — |
What people said
All 6 comments that mention it, newest first. Each links to the original comment.
“If your platform/sdk/browser/standard-library comes with zlib/gzip/.. then it's often easier to just pick that.”
“the inflate algorithm is tiny”
“Zlib is an universal compressor but does not converge to the entropy of a sequence very fast.”
“AA and others like libgen and zlib have done a great job spreading knowledge in the world”
“There's so many C libraries like this”
“on my machine, it's about 10x faster to use zlib”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.