ZIM (file format)

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title: "ZIM (file format)" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["archive-formats", "wikipedia", "open-formats"] description: "Open file format that stores wiki content for offline usage" topic_path: "general/archive-formats" source: "https://en.wikipedia.org/wiki/ZIM_(file_format)" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Open file format that stores wiki content for offline usage ::

::callout[type=note] the open file format ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/e/ec/Kiwix_for_Android_scr1.png" caption="Wikipedia for Schools]] in offline usage"] ::

The ZIM file format is an open file format that stores website content for offline usage. The format is defined by the openZIM project, which also supports an open-source ZIM reader called Kiwix. The format is primarily used to store the contents of Wikipedia and other Wikimedia projects, including articles, full-text search indices and auxiliary files.

and native category and image handling similar to MediaWiki, and the entire file is easily indexable and readable using a program like Kiwix – unlike native Wikipedia XML database dumps. --

ZIM stands for "Zeno IMproved", as it replaced the earlier Zeno file format. Since 2021, the library defaults to Zstandard file compression and also supports LZMA2, as implemented by the XZ Utils library. Most notably, the compression ratio can be up to 3x with almost all of the space savings taking place within the clusters. The openZIM project is sponsored by Wikimedia CH and supported by the Wikimedia Foundation.

References

References

1. (2024-09-10). "openzim/zimit". openZIM.
2. "openZIM project wiki".
3. Truong, Kevin. (2020-07-10). "You Can Download the Entirety of English Wikipedia to Browse Offline".
4. "Zeno File Format". openZIM.org.
5. ".ZIM File". FILExt.
6. "Release 7.0.0".
7. "ZIM Format Block Diagram".

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::