TonyLu786 / WorldLedger
Record the chunks you actually see on a multiplayer Minecraft server and rebuild them as a single-player world. Client-only Fabric mod for 26.2 plus a CLI.
TonyLu786 / WorldLedger
thearchive-world / archive-world-downloader
A Minecraft World Download mod. Save a Minecraft multiplayer world as a singleplayer world you can open offline: the terrain as you explore it, containers as you open them.