PgModeler [0], cannot recommend it enough. You have to compile yourself the free version (it's open source - you pay if you want to directly download the precompiled binaries) and it's a bit of work if you want to include the query optimizer plugin, but there's documentation and GitHub issues with solutions already in place. Once you compile it for the first time and start using it, you'll keep doing it again with each new version. I haven't found a better Postgres tool yet.

edit: it's a cross-platform tool, supporting Linux, Mac and Windows (32/64)

[0]: https://pgmodeler.io/