Great question. I've thought hard about this. I originally built it to be online-first, thinking "you can add offline support later". This is the version that's demoed in the video on the Github - and is over a year old at this point. I abandoned this for multiple reasons:

1. Adding offline support is very nontrivial. It (may) influence your choice of DB and your data schema. This is a type of master-master replication, since the user is the master of their data, and this is quite painful in RDBMS-land. I'm avoiding having to migrate my schema to support offline sync.

2. There already exist solutions that are online-first. E.g. Quizlet, mochi.cards, remnote. I find all their tools for collaboration lacking, despite being online-first... which is surprising. They don't even support something as basic as commenting on a card. This blows my mind. Imagine Github without issues/discussions/pull requests.

3. Users have repeatedly told me that they prefer offline-first. This is probably due to them coming from Anki - a popular open source offline-first program. Anki is my real "competition" - not billion-dollar Quizlet.