A list of current European Bank Developer portals:
ABN Amro
Banca Sella
Bank of Cyprus
Barclays
BBVA
Ceska Sporitelna
Citi
Danske Bank
Deutsche Bank
Fidor
Hellenic Bank
HSBC
Lloyds Bank
MKB Bank
NGB i-Bank
Nordea
Royal Bank of Scotland
Saxo
Sbanken
SEB
Spar Nord
Starling Bank
Swedbank
Visa
You can keep updated on Open Banking progress by joining the LinkedIn group - Open Banking Developers Europe.