Because these API are not meant to be public for the end user to use.

Access to that kind of data requires regulation, a lot of it and that's why Third Party Providers exist. There are a lot of them in Europe and they're not expensive.

I actually didn't expect to find anything about bunq around here but I have to say they're the worst bank I've worked with. When we started working with them, their API were broken and the devs had no idea why. It seems to have improved recently but it's definitely not a bank to praise for their API.

Whilst not PSD2/PSD3, I've been super happy with Wise; an excellent API, good quality docs. A _proper_ test environment that you can drive using hooks they expose. Nothing but praise for them, including their support, which has helped me around the clock even on weird questions such as why my custom integration fails to send a transaction (mismatched currency between recipient and transfer in my code).

In Hungary you don't get documentation for these APIs only in pdfs via email, and if you get it the APIs are not stable, constantly breaking. I was always dreaming about creating an automated testing suite and report all of the issues automatically to the national bank, which is the supervisor of all commercial banks in HU, in a hope to punish them.

> "Open banking" is kind of a thing with PSD2/PSD3, but in name only. In reality, it's impossible to build anything useful

You mean the step from sandbox to production application, or you're not even getting access to the sandbox itself? I managed to get sandbox access with ease via two separate banks (both Spanish though), with no problems, think it took them one (working) day or something to review my "application". I never tried to get anything into the production environments though, but makes sense they'd be a bit tighter on that tbh.

Not sure why you'd claim it's impossible, it's in wide use already by banks, fintech and payment service providers across the union.