I have used Retool to create a (well-received) PoC of an internal-facing admin app. I was pretty impressed, even though it had some rough edges.

Setting up UIs was relatively painless thanks to many out-of-the-box integrations, and it was surprisingly easy to implement auth/error handling/component dependencies.

The thing I liked the most is that it's not really a "no code" - you need to be technical to build good apps in this tool. However, that's where the power comes from - it simplifies the mundane development tasks and lets you focus on something more high level.

I wish the team would make it easier to consume your own, custom API however.