dbForge Data Compare for PostgreSQL is described as 'table data comparison and synchronization tool, which allows you to detect data differences in compared PostgreSQL tables, generate data synchronization script and execute it to eliminate all the differences'. There are five alternatives to dbForge Data Compare for PostgreSQL for Windows, Linux and Mac. The best alternative is Aqua Data Studio. It's not free, so if you're looking for a free alternative, you could try EMS SQL Manager for PostgreSQL. Other great apps like dbForge Data Compare for PostgreSQL are Replicator (Paid), PostgreSQL Maestro (Paid) and Altova DiffDog (Paid).
Whether you need to simply compare two databases or set up replication, you have come to the right place. Replicator does not change the reference database in any way nor requires setting up customs agents or triggers in your databases.