How do you test your app before deploying it?

The company I work for uses ghostinspector for end-to-end testing.
I recently started to use playwright for my personal projects and I like it much better.

I would like to know how others do testing.

• Do you test the core functionality manually before you release?
• Do you use any automated e2e testing tools / frameworks?

I'm looking forward to get some ideas from the comments :)

Thanks.