[Feature Request] zsync adoption for AppImage updates

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#18,932 opened on Apr 12, 2026 0 comments 5 reactions 0 assignees View on GitHub

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feature request

Dominant language: C
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Description

zsync is becoming increasingly popular for distributing AppImage updates. For instance, current releases of PPSSPP, Ryujinx (Ryubing), and Vita3K all provide zsync support.

From https://github.com/libretro/docs/pull/1135#issuecomment-4231783802

Given the size of the packages, it would be even easier to update them if they were redistributed outside of the 7z archive that contains them, and with the necessary information for delta updates.

I wrote a guide to implement this information and make AppImages faster to update using appimageupdatetool and zsync. It is just 5 minutes reading:

https://github.com/ivan-hc/AppImage-tips

I'm the maintainer of AM. Thanks @davidhedlund for the support.

AppImages

Needed zsync files

Contributor guide

Open the contributing guide

First steps

Read the whole issue, then the project's contributing guide.
Comment on the issue to say you are picking it up — it saves two people doing the same work.
Fork the repository and make your change on a branch.
Open a pull request that references the issue number.

Research direction

Start by reviewing the listed AppImage 7z release artifacts under buildbot.libretro.com and the linked AppImage zsync guide. Done means the nightly and stable x86 and x86_64 RetroArch and RetroArch_Qt artifacts have corresponding .zsync files available.

Written by the indexing model from the issue text.

Assessment

Domain: build-system, release
Issue type: Feature
Difficulty: 4/5
Estimated time: 3-5 days
Activity status: Quiet
Clarity: Mostly clear
Newbie friendliness: 55/100