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 an 11.4GB Windows security event log — JSONL format with one JSON object per line — from a real Windows server. These logs capture security-critical events: process creation, logon sessions, privilege usage, and more.
A typical line looks like:
{"UserName": "Comp607982$", "EventID": 4688, "LogHost": "Comp607982", "LogonID": "0x3e7", "DomainName": "Domain001", "ParentProcessName": "services", "ParentProcessID": "0x2ac", "ProcessName": "svchost.exe", "Time": 1, "ProcessID": "0x1418"}
Results
| Compressor | Size | vs xz -9 |
|---|---|---|
| xz -9 | 390.3 MB (370.5 MB) | baseline |
| Smallest.zip | 10.1 MB (10.0 MB) | -97.6% |
Smallest.zip compresses the security event log to 10MB — that's 99.9% smaller than the original 11.4GB file, and 97.6% smaller than xz at maximum compression.
Key Takeaways
This is our best result yet against xz — a 97.6% improvement over what's already considered the gold standard of general-purpose compression.
The numbers are striking: xz produces 370MB of output. Smallest.zip produces 10MB — that's 37x smaller. For security teams retaining months or years of event logs for compliance and forensics, this compression ratio transforms what's feasible to store and search.
Try It Yourself
Upload your own files at smallest.zip and see the difference. Every account starts with free credits.