Which tool should I buy to synchronize databases?

You will need Full Convert Pro app to be able to perform data synchronization.

In the Pro plan, the replication project type exists and it will compare all tables one by one, noting the differences in data. It will then apply absolutely minimal set of changes to the target database to make its data same as data in source database. Usually, this will amount to a few dozens or hundreds of UPDATE statements, and bulk insert of new data, which is very fast. Advantage of this approach is that your target database is usable all the time. Its state is never half-empty, as we don't load all data on each run. So, replication can be scheduled often. Many customers perform the replication every 15 minutes or so.

However, the replication project doesn't create your target database, you may need to create separate data copy project to completely recreate your target database at least once - if you don't already have compatible tables in the target database. If you only need to replicate data overnight, when nobody is using the target database, you may choose to schedule a Full Convert data copy project. It will fully overwrite affected target tables, dropping them and recreating them as it goes (by default).