The Test
We use xz -9 as our baseline — it's widely regarded as the strongest general-purpose compressor available and the standard benchmark for maximum compression.
We took a 4.9MB Apache log file — 56,000 lines of mixed error logs, notice messages, and access logs — and ran it through every major compressor at their highest settings.
Results
| Compressor | Size | vs xz -9 |
|---|---|---|
| gzip -9 | 241,025 | +33.2% |
| zstd -19 | 178,235 | -1.5% |
| xz -9 | 180,972 | baseline |
| bzip2 -9 | 173,827 | -4.0% |
| Smallest.zip | 45,908 | -74.6% |
Smallest.zip compresses the Apache log to 46KB — that's 99.1% smaller than the original 4.9MB file, and 74.6% smaller than xz at maximum compression.
Key Takeaways
The traditional compressors are tightly clustered between 174–241KB. Even the best of them (bzip2) only manages a 4% improvement over xz. Smallest.zip blows past all of them — producing output that's nearly 4x smaller than bzip2 and 5x smaller than gzip.
Apache logs are particularly interesting because they contain a mix of structured and semi-structured data: timestamps, IP addresses, HTTP methods, URL paths, status codes, and free-form error messages. This diversity usually makes compression harder, but Smallest.zip handles it efficiently.
Try It Yourself
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