An isolated test environment that replicates a bank's or provider's API, using fictitious data, so developers can build and test an integration without touching real accounts.
Under PSD2, banks must make a testing facility available to third parties before going live. A sandbox is also how a software company validates an integration after a bank changes its interface.
The term is also used for regulatory sandboxes, where a supervisor lets firms test innovative services under relaxed conditions. The two meanings are unrelated.
