[This advice is targeted at beginner developers]
Advice for people making DID/OSDD management apps:
Do not use online website builders or online app builders, they will hold you back.
Use an actual development environment installed on your actual computer. If you don't want to do this, something like GitHub codespaces could also work.
AI coding assistants can be helpful, but you must have enough programming knowledge to know whether to accept what the AI wants to do to use them effectively. AI is often confidently wrong.
Store your code on GitHub and use proper git version control. Private repos are available if you would rather keep your code private.
Use one of the big cloud providers for hosting, but be sure that you understand how you are billed and choose resources accordingly. You can end up with a huge bill you can't pay if you set things up wrong.
Most cloud providers have a certain amount of resources that you get for free. It is possible to design things so that you stay within these free limits
Protect your REST APIs with API keys that you don't share, this will help prevent you from getting a big bill.
NoSQL / document type databases are often cheaper than things like MySql or SQL server
consider just storing data locally, no server costs that way!
Javascript or Typescript based app frameworks are probably the easiest for a beginner to get started with.
If building for Android back up your release signing key and store it securely. You will not be able to update your app without it.
If building a web site or a rest API for an app, learn about the OWASP Top Ten security vulnerabilities and make sure that you do not have them in your app.
Allow people to export their data to JSON, data sovereignty is important and is a legal requirement if your app can be downloaded or accessed in EU countries.
Do not check secrets like database passwords or keys into git source control.
If your app grows beyond a few users, at some point you will need to talk to actual lawyer about the legalities of your operations. Terms of service and things like that usually need the help of a lawyer.
Unless you are building a completely offline app that is deployed through sideloading, you will probably have to spend some money on this