Some cool collaboration/sync/privacy research by Kleppmann et al at Ink & Switch: https://www.inkandswitch.com/local-first.html . Nextcloud should have got at least an honorable mention ( https://nextcloud.com/ ).
Conflict-free Replicated Data Types (CRDTs) sound cool.
Many interesting links in there, including the library of congress recommended formats: https://www.loc.gov/preservation/resources/rfs/TOC.html
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