@simonlou@typo.social So, the Spanish Tax Agency wants all invoices to be locally signed, then uploaded to them with a signature hash that can include the preceding Invoice in a "series" (each series' Invoice must have a corresponding increasing number / ID attached) if applicable, and then they return a status such as 'OK'. Then, when printing / exporting the Invoice after the upload, you must attach a QR code. This QR code is essentially a link to the Spanish Tax Agency with the ID and signature of the uploaded Invoice as part of the URL so the invoice can be contrasted via the Tax Agency records that indeed this Invoice is 'verified'. The QR Code opens the website and triggers a Tax Agency search for a matching record, and displays the result as the website. Additionally, which is what I've also added to my app, you can check as a standard API instead of website to get 'does this record exist?' It's not complicated API, except for the fact I think it belongs in the 2000s because it's SOAP and XML. But they have "decent" (by Spanish standards) documentation and have replied quickly to my questions (I wish they did the same for taxes, not APIs!) This will be mandatory starting next year, and it's being treated as a big cash grab / funnel through which existing apps get paid MONTHLY! to access your data, even though the tax agency APIs are all free. There's no form of gatekeeping whatsoever around making a product for this. 'No thanks' was my answer, so I wrote my own thing. Well, I'm in the process of it. They have matching servers as a 'test environment' for every possible request so, I have confidence I can 'emit' proper Invoices when I decide to toggle the APIs to talk to the real thing. There is a 'free' app available to all Spanish citizens, but it's a really really bad webapp.
