Maximum of connections in PG

Dear Members!

In a very strong Linux machine (with many 16-30 GB RAM) what is the limit
of the PGSQL server (9.4-9.5) "maximum connections"?

1000?
2000?

The clients are native applications (Windows executables) with persistent
connections, with more than 100 databases (every client have only one
database connection).

Now we must determine where is the upper limit to know when we must buy a
new machine to customers clients (which have to migrate in future).

I know my question is too common without precise numbers, but what is I
need is your experiences in this theme?
What areas are problematic when we increase the "max_connection" number?

Thanks for any info!

Best wishes
dd