Igor Pavlov released the free, open-source 7-Zip application in 1999, and introduced its native .7z archive format in 2001 alongside LZMA, the Lempel-Ziv-Markov chain Algorithm he had been developing since 1998. LZMA extends the LZ77 dictionary-matching idea used by DEFLATE (the algorithm behind ZIP) with a much larger search window and range coding in place of Huffman coding, which typically produces smaller files than ZIP at the cost of slower compression time. Pavlov released both the 7-Zip application and the underlying LZMA SDK freely \u2014 the SDK sits in the public domain, and 7-Zip itself is licensed under the LGPL \u2014 which is a large part of why 7z spread quickly as a no-cost alternative to commercial archivers.<\/p>
For a DAM, 7z is the practical choice when compression ratio actually matters \u2014 bundling a large batch of assets for cold storage or a big client handoff where every gigabyte saved reduces transfer time and storage cost. Because the format and its reference tooling are open source rather than proprietary like RAR, a DAM can build extraction and creation into a server-side pipeline (via libraries like py7zr) without licensing risk, though 7z’s lack of built-in OS support on Windows and macOS means end users receiving a 7z archive directly usually need to install an extraction tool first \u2014 worth weighing against ZIP for anything meant for a non-technical recipient.<\/p>","protected":false},"excerpt":{"rendered":"
An open-source, high-ratio lossless archive format built around Igor Pavlov’s LZMA compression algorithm, offering better compression than ZIP at the cost of slower compression speed.<\/p>\n","protected":false},"author":0,"featured_media":0,"template":"","meta":{"footnotes":"","faq":[{"question":"Why does 7z usually produce smaller files than ZIP for the same content?","answer":"7z's default LZMA\/LZMA2 algorithm uses a much larger compression dictionary and range coding instead of ZIP's Huffman coding, which generally finds more redundancy and encodes it more efficiently, at the cost of taking longer to compress."},{"question":"Is 7z open source, unlike RAR?","answer":"Yes \u2014 the 7-Zip application is licensed under the LGPL and the underlying LZMA SDK is in the public domain, which is a key reason DAM pipelines can build 7z support into server-side tooling without the licensing questions that apply to RAR."},{"question":"Does Windows or macOS open 7z files without extra software?","answer":"No \u2014 neither OS has built-in 7z support; Windows needs 7-Zip (or a compatible tool) and macOS needs something like Keka or The Unarchiver."},{"question":"Can a 7z archive encrypt filenames, not just file contents?","answer":"Yes \u2014 7z's AES-256 encryption option can be set to hide the archive's file list along with the data, which ZIP's more common encryption schemes typically don't do."},{"question":"What compression methods can a 7z container actually use?","answer":"LZMA and LZMA2 by default, with optional support for PPMd, BZip2, and a few others \u2014 the .7z extension refers to the container format, which can wrap different underlying compression algorithms per archive."},{"question":"Is 7z a good choice for archiving a large DAM asset collection for cold storage?","answer":"Yes \u2014 its high compression ratio reduces storage footprint meaningfully compared to ZIP, and its open specification and tooling avoid the long-term support risk of a closed format like RAR."},{"question":"Can a DAM extract 7z archives programmatically without shelling out to a CLI tool?","answer":"Yes \u2014 libraries like py7zr for Python or Apache Commons Compress for Java implement 7z extraction natively, which is useful for building automated ingest pipelines."},{"question":"When was the LZMA algorithm behind 7z developed?","answer":"Igor Pavlov began developing LZMA in 1998, and it became the default compression method of the 7z format when he introduced it in 2001."}],"checked_date":"2026-08-07","sources":[{"statement":"7-Zip, developed by Igor Pavlov, was first released in 1999; its native .7z archive format followed in 2001.","source_name":"Wikipedia \u2014 7z","url":"https:\/\/en.wikipedia.org\/wiki\/7z","checked":"2026-08-07"},{"statement":"7-Zip is licensed under the GNU LGPL (with an unRAR-code restriction), and the LZMA SDK it's built on is in the public domain.","source_name":"Wikipedia \u2014 7-Zip","url":"https:\/\/en.wikipedia.org\/wiki\/7-Zip","checked":"2026-08-07"}],"kicker":"","fact_checker":0,"reading_time":0,"revisions":[],"seo_title":"","seo_description":"","noindex":false,"ext":"7z","full_name":"7-Zip Archive Format","vendor_name":"Igor Pavlov (7-Zip)","introduced":"1999 (7-Zip application); 7z format introduced 2001","container_notes":"A 7z archive separates its file data from its metadata (filenames, attributes) more strictly than ZIP does, and supports several compression methods behind one container \u2014 LZMA and its successor LZMA2 by default, plus optional PPMd, BZip2, and others \u2014 as well as AES-256 encryption that can optionally hide filenames along with content. LZMA itself is a dictionary-based algorithm descended from the same LZ77 family as DEFLATE but with a much larger dictionary and range coding instead of Huffman coding, which is what gives 7z its typically smaller output size than ZIP on the same input.","open_with":[{"platform":"Windows","how":"7-Zip (the free, open-source reference application) creates and extracts .7z natively"},{"platform":"macOS","how":"Keka or The Unarchiver, both free, add 7z support since macOS has no built-in handling for it"},{"platform":"Linux","how":"p7zip (the Linux port of 7-Zip) via command line, or through most desktop archive managers that link against it"},{"platform":"DAM\/asset pipeline","how":"The open-source py7zr (Python) or Apache Commons Compress (Java) libraries let a DAM extract and inspect 7z archives server-side without shelling out to the CLI"}],"archive_advice":"7z is a strong choice when a DAM needs to bundle assets with maximum space savings \u2014 its LZMA\/LZMA2 compression reliably beats ZIP's ratio on most content \u2014 and its open-source reference implementation (LGPL, with the LZMA SDK in the public domain) removes the vendor-lock concern that applies to RAR. The trade-off is slower compression and somewhat less universal native OS support than ZIP, so it suits DAM cold-storage or archival bundling more than everyday delivery to end users who may not have an extraction tool installed.","related":[],"tool_link":""},"silo":[23],"class_list":["post-3044","format","type-format","status-publish","hentry","silo-formats"],"_links":{"self":[{"href":"https:\/\/picajet.com\/articles\/wp-json\/wp\/v2\/format\/3044","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/picajet.com\/articles\/wp-json\/wp\/v2\/format"}],"about":[{"href":"https:\/\/picajet.com\/articles\/wp-json\/wp\/v2\/types\/format"}],"version-history":[{"count":0,"href":"https:\/\/picajet.com\/articles\/wp-json\/wp\/v2\/format\/3044\/revisions"}],"wp:attachment":[{"href":"https:\/\/picajet.com\/articles\/wp-json\/wp\/v2\/media?parent=3044"}],"wp:term":[{"taxonomy":"silo","embeddable":true,"href":"https:\/\/picajet.com\/articles\/wp-json\/wp\/v2\/silo?post=3044"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}