Hi there - full disclosure, I work at Plaid . Anyone can signup for API keys and access all the thousands of banks that we currently support on Plaid for free in our dev environment.
Once you want to add more than 100 accounts, we recommend reaching out to learn more about pricing at scale; it depends on what APIs are being used, how much data is being pulled, how often, etc. Feel free to shoot me an email directly if you have any questions! (charley@plaid.com)
Ah, I had used it couple of years ago. At that point, I could get to my bank account with it at a major bank, authentication with smaller credit unions was restricted until I graduated from the dev environment.
Once you want to add more than 100 accounts, we recommend reaching out to learn more about pricing at scale; it depends on what APIs are being used, how much data is being pulled, how often, etc. Feel free to shoot me an email directly if you have any questions! (charley@plaid.com)