What is the plural of "API" (Application programming interface)

Is it part of English irregular plurals ending in "-i"?

  • 4
    Without any more context, I'd say add an "s." APIs. – vickyace May 5 '16 at 11:59
  • 3
    If you're talking about Application Programming Interfaces, the well-established plural is "APIs". – Hot Licks May 5 '16 at 12:01


API could mean a lot of things. The list can be easily found on https://en.wikipedia.org/wiki/API_%28disambiguation%29.

But as it is in most cases an acronym, when you append s to it, it unambiguously indicates plurality of whatever the acronym stands for.

As in Computer science - API stands for Application Programming Interface. The plural of which is Application Programming Interfaces so the acronym in plural is APIs

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