[jjeaff]

I used TurboTax online last year and was pretty happy with it's ability to import 1099 data from several companies I use like vanguard and Ameritrade. So the PDFs aren't standardized but many providers have apis to pull the data. In fact, they may be using something like Plaid that consolidates all the APIs into one.

[junar]

Well, TurboTax happens to be the most widely used large commercial tax software, and the brokers you mentioned are also quite large and popular. Whatever integration has been done is almost certainly proprietary and not freely reusable.

Hypothetically, even if an API existed, building the integration in your own app also costs FTE hours that are likely drawn away to higher priority tasks.