Two years ago, I started building my own project management tool.
Today, I use it for all my clients, and my clients use it themselves as well. It lets you manage tickets, documents, transcriptions, and more, and query them using an internal AI. The good thing is, that you can choose which AI you want to use. The system is available as a cloud platform, but also as open source (AGPL). It is well documented and thoroughly tested. This is not just a weekend project, it now has about 150,000 lines of code and around 24,000 RSpec tests. It is absolutely ready for serious business use. I made a docker for it, so the setup is very easy.
A short demo version without a signup:
https://demo.lalabase.com