Congrats on the launch! The app builder looks amazing and seems indeed very inspired by Retool.
We are building a tool in the same space with Windmill, also open-source [1]. The goal is not to hijack this thread since I do not believe we are that competitive.
We focus on workflows and more backendy/complex logic by converting automatically Python, Typescript, Go, Bash into endpoints and workflow modules that you can run at scale on workers that are deployable on one's own infra. We are currently also finishing an UI builder [2] but because it is not our prime focus, it will always be a much simpler alternative to what you and Retool are building. Hence, I see a lot of potential for integrations/collaboration for users with need of UIs similar to retool while needing more complex logic than REST or raw database queries.
In any case, congrats, I have played with the tool and you guys did an amazing job.
[1]: https://github.com/windmill-labs/windmill [2]: https://github.com/windmill-labs/windmill/pull/886
Even for the simplest and my own sites, I usually typed it out in the browser and copy-paste. :-)