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7z vs ZPAQ

A side-by-side feature comparison.

Summary

7z is the everyday champion of compression ratio; ZPAQ pushes ratios still further using context mixing — but at glacial speed. ZPAQ also happens to be a journaling archiver that deduplicates data across snapshots, making it a hybrid backup format.

Bottom line: 7z for daily archives. ZPAQ for backup deduplication or maximum-ratio research.

Feature comparison

Feature 7z ZPAQ
Algorithm LZMA2 Context mixing (configurable)
Speed Slow Glacial
Ratio Excellent Best in class
Deduplication No Yes (journaling)
Snapshots No Yes
Tooling Mature Niche

About 7z

7z is the native format of the open-source 7-Zip archiver, designed by Igor Pavlov in 1999. It uses the LZMA family of algorithms and almost always produces smaller files than ZIP or RAR. 7z supports solid compression, where many files are compressed as one continuous stream, and AES-256 encryption with optional filename hiding.

Read the full 7z guide →

About ZPAQ

ZPAQ is an experimental high-compression archiver from Matt Mahoney that uses context-mixing neural-network-style models. It produces some of the smallest archives ever measured but compresses extremely slowly — gigabytes per hour rather than per second. ZPAQ also supports incremental, deduplicating snapshots.

Read the full ZPAQ guide →

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