2017: Smart Sync ships — and 'online-only' files confuse and catch users out
2017
Dropbox's Smart Sync (formerly Project Infinite) let files appear in the file manager without being downloaded — convenient, but a recurring source of confusion when 'online-only' files were unavailable offline or seemingly vanished.
What happened
Smart Sync, which reached general availability for business and Plus users in 2017 after being previewed as 'Project Infinite,' shows every file in the Dropbox folder as a placeholder that downloads only when opened. It solves a real problem — fitting a large cloud account onto a small local disk — but it also created a persistent class of user confusion.
Files marked 'online-only' look present but are not actually on the device, so they are unavailable without a connection, can fail to open when traveling, and can be misread as lost when an app expects a real local file. Combined with Dropbox's separate Selective Sync feature and later OS-level 'Files On-Demand' integrations, the result was a tangle of overlapping mechanisms that ordinary users struggled to reason about — and that, in edge cases, contributed to perceived or actual data unavailability.
The feature itself works as designed; the issue is the cognitive and reliability cost of placeholder files that look local but are not, layered on top of older sync mechanisms with similar-sounding names.
Impact
Smart Sync is emblematic of how added sync 'convenience' features can degrade the core promise that a file in your Dropbox folder is really there. The online-only model is now standard across cloud-sync products, but Dropbox's overlapping Selective Sync / Smart Sync / Files On-Demand terminology made it unusually easy for users to lose track of where their data actually lived.