[aaviator42]

SQLite is insanely robust. I have developed websites serving hundreds of thousands of daily users where the storage layer is entirely handle by SQLite, via an abstraction layer I built that gives you a handy key-value interface so I don't have to craft queries when I just need data storage/retrieval: https://github.com/aaviator42/StorX

[arunix]

Does StorX have any special handling of concurrent writes, or would the user need to take care of that?

[aaviator42]

We use SQLite IMMEDIATE transactions, which lock files for writes for a few milliseconds while commiting data to the file. This is not a problem in practice until you reach more than dozens of concurrent writers. StorX configures a default busy timeout of 1.5s, but it can be configured as per your needs. You can also get a lot more out of it by being smart about how you spread your data over DB files (eg: one file per user instead of one for multiple/all users), and also by considering when you call openFile() and closeFile() (eg: keep write transactions short, don't leave a file handler open while running long calculations).