To save bandwidth when downloading Steam games the files are sent compressed then uncompressed on the end user's PC. What compression algorithm is Steam using to do this?

  • I found an article on SteamDB (which isn't affiliated with Steam) that says it uses LZMA. But I don't know how that works on end-users machines. I would assume the machine would need to support the algorithm/have the necessary libraries installed in order to decompress the downloaded workload. But maybe when one installs Steam, it installs the needed compression libraries as well onto the machine.
    – Timmy Jim
    Aug 16, 2022 at 20:43
  • 3
    @TimmyJim It is absolutely the case that the Steam app will bundle the necessary decompression tech if that tech is not guaranteed to already exist on every OS that Steam targets.
    – Tom
    Aug 17, 2022 at 0:17

1 Answer 1


SteamDB (which is not affiliated with Steam itself) has a post that says they (Steam) use LZMA:

Each file is split into roughly one megabyte chunks, and each chunk is compressed with LZMA and encrypted with an AES 256-bit key.

I was unable to find any official documentation. It's probably not publicly available. As mentioned previously, during installation of Steam, it probably will install or at least come bundled with the necessary files/libraries needed to decompress the files on the end users device.

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