DBeaver is solid and supports the most DBs with lots of handy features: https://dbeaver.io/

Jetbrains Datagrip is popular too, more intelligent but less DBs than DBeaver: https://www.jetbrains.com/datagrip/

If you want a web-based tool, especially for Postgres, then OmniDB is a good choice: https://www.omnidb.org/en/

I'll second DBeaver.

third!

fourth dbeaver db support and data model diagramming

Interestingly, OmniDB is built with Django.

DBeaver has support for many databases through JDBC.

I recently discovered DBeaver and can highly recommend it. It is a bit more complicated to use than some alternatives, but really powerful. Also supports a large number of databases. https://dbeaver.io/

For Mac and Windows I really like TablePlus: https://tableplus.io/

First saw it here.

I've been using TablePlus as well. I like that it has true native UI and the redis support is handy.

Yup - TablePlus is beautiful. I tried it for a few days and paid for it, really works wonderfully on macOS.

I use three tools interchangeably. DBeaver as mentioned by other comments. Squirrel SQL[0] has been around for a very long time. I have been using it for well over 10 years. Probably 15. Don't be fooled by the dated screenshots. First thing I always do it change the look and feel to Windows native then looks like any other Windows application. SQL Workbench/J[1]. Has tonnes of features, is well documented. I particularly like the headless mode which allows me to automate running of SQL statements using a batch file.

[0]http://squirrel-sql.sourceforge.net/ [1]https://www.sql-workbench.eu/

I would argue Datagrip has yet to fail me while having a ton of support for many databases. Including support for MySQL 4.0.16. I had to use that DB for my previous job about a year ago. With datagrip I just needed to download an old jar file and I had a connection automatically.

A simple postgres client I'm working on in my free time: https://sanchosql.com/ Linux only now but it's open source so it should be possible to compile for win/mac

I use Valentina:

https://www.valentina-db.com/en/

it work well. Even work with Sql Server on osx!

DBeaver is popular if sluggish at times

I enjoy Sqlectron. Good cross-platform support, and a terminal option if you'd prefer.

I'm a big fan of Aqua Data Studio. I'd never heard of it until my current position, but it's very nice.

DataGrip (not OpenSource) is pretty good.

Can only say 10000 good things about DataGrip

I like DBeaver. YMMV.