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mozlz4 vs Modern7z: catalog facts
mozlz4	Modern7z
Best for: Editing Firefox profile files such as search.json.mozlz4 by hand	Best for: 7-Zip users who need to open or create Zstandard, Brotli or LZ4 files
Free Free and open source under the MIT licence.	Free Freeware under TC4Shell's terms of use.
Windows, Linux, Command line	Windows
Opens Firefox's mozlz4 files that general archivers cannot read Compresses edited files back into mozlz4 All 3 strengths for mozlz4 Opens Firefox's mozlz4 files that general archivers cannot read Compresses edited files back into mozlz4 Precompiled binaries for Windows and Linux	Adds Zstandard, Brotli, LZ4 and other modern methods to 7-Zip Opens Zip archives compressed with ZSTD or Brotli All 4 strengths for Modern7z Adds Zstandard, Brotli, LZ4 and other modern methods to 7-Zip Opens Zip archives compressed with ZSTD or Brotli Handles Firefox jsonlz4 files 32-bit and 64-bit builds
Overwrites existing output files without asking Single-purpose tool with a small feature set	Needs 7-Zip and a manual install into its Codecs folder The new methods compress single files, so multiple files need a TAR container All 3 limitations for Modern7z Needs 7-Zip and a manual install into its Codecs folder The new methods compress single files, so multiple files need a TAR container Closed source
Downloadable app	Downloadable app
Open source	Not open source
License: MIT	License: Freeware
No account needed	No account needed
Offline features available	Offline features available
Official website Full listing and sources Sources for mozlz4 github.com/jusw85/mozlz4 Catalog checked October 2, 2026	Official website Full listing and sources Sources for Modern7z tc4shell.com/en/7zip/modern7z Catalog checked October 2, 2026

“Not stated” means we have not confirmed it. Features can vary by device and plan.