What are ways to do offline/online databases right?

The idea is to time an sports event.

There are bunch of checkpoints and internet connection might not always be available.

So what are ways to do an application as such that would run on desktop ( thinking if Electron would do it ) that could store data locally when internet connection isn't available and then send it to main database if possible so it could be displayed on the web.

Each computer/app would provide data only for that particular checkpoint. That would mean only 1 field would need to be filled for that competitor ( timestamp for that checkpoint ). For example database entry per competitor would look something like: id, competitorId, name, time_checkpoint_1, time_checkpoint_2 etc....

Would like to do web part with Laravel but now am wondering what database to use so data could be synchronized.

Basic flowchart of the idea.

Open for ideas what databases,programming languages,solutions to be used in this case.