Measured - byte-exact - 2026

Pedulli vs xz

measured head-to-head - structured data classes - byte-exact SHA-256 verified

TL;DR - honest
Pedulli is a best-of-N racer: it races xz, zstd, brotli and your data's SRD math, keeps the smallest verified output, always byte-exact (SHA-256 roundtrip) with a +1 byte never-worse floor on its own output. Because xz is one of the racers, Pedulli is never larger than the best standard codec (worst case +1 byte): it wins outright on structured classes (JSON, periodic, sparse) and ties the best codec on already-optimal / random data - including long English text, where it simply selects xz's own LZMA2 result.

The measured table

All numbers measured on this server, roundtrip-verified SHA-256 byte-exact. Proofs available on request.

Input	xz -9 -e	Pedulli (best-of-N)	Δ
MP4 master 10 MB	9,468,380 B	9,430,108 B	-38,272 B
1 MiB of zeros	156 B	13 B	much smaller (redundant input)
1 MiB periodic binary	1,108 B	436 B	-61%
JSON 31 KB	4,360 B	1,265 B	-71%
Long English text 500 KB	~145 KB	~145 KB	tie - selects xz's LZMA2 result
HTML 161 KB	35,705 B	35,705 B	tie - selects xz's LZMA2 result
Apache logs 3.5 MB	211 KB	211 KB	tie - selects xz's LZMA2 result
Random bytes 1 MB	1,049,000 B (+424 B)	1,048,577 B (+1 B)	423 B less overhead

Where xz alone is the right call (honest)

Long English / generic text. xz's large LZMA2 preset dictionary is hard to beat on plain prose over ~100 KB - so on that class Pedulli's racer simply selects xz's own result and ties it, never larger.
Universally installed. Every Linux distro ships xz. Pedulli is the web service or API.
Single-pass speed at low levels. Faster than Pedulli's coder race at xz levels 1-3.

What Pedulli does that xz does not

+1 byte never-worse floor. Pedulli's own output is never more than 1 byte over the input. xz adds 424 bytes on random data - pure waste per file at scale.
Best-of-N racing. Several internal coders run; the smallest byte-exact result wins, so structured classes (JSON, periodic, sparse) come out tighter.
Web-native + API. In-browser for small inputs, REST API for backup / log pipelines. xz is CLI only.
Zero data retention. GDPR by design, EU-sovereign.

When to switch

Switch to Pedulli for video masters, JSON/XML telemetry, periodic sensor streams, and the per-file +1 byte never-worse floor. On long English-text archives Pedulli ties xz by selecting its LZMA2 result - so you are never worse off than xz, and you win on every structured class.

Run the free trial Pricing / API All benchmarks

More comparisons: gzip - zstd - 7-Zip - brotli - zpaq