API (disambiguation)

An API, or application programming interface, is any defined inter-program interface.

API or api may also refer to:

Companies and organizations

Academic Programs International, an American study-abroad provider
American Petroleum Institute, an American trade lobbying organization
AmeriStat Pharmaceuticals, Inc., a US-based international wholesaler and exporter of pharmaceuticals and medical supplies
Animal Protection Institute, an American non-profit organization
Anonima Petroli Italiana, an Italian petrol (gasoline) company
Anton Pannekoek Instituut, astronomical institute of the University of Amsterdam
Associated Producers Incorporated a B picture subsidiary of 20th Century Fox
Athletes' Performance Institute, an American training facility for competitive athletes
Australian Pharmaceutical Industries
Australian Property Institute, an Australian professional organization in valuation
Automated Precision, Inc., an American advanced metrology solutions company
Automated Processes, Inc., an American audio electronics company
Automobile Products of India, an Indian automotive company
Aviation Partners Inc., an American aviation components company

Academic Performance Index, a measure of scholastic performance used in California, United States
Auburn University, formerly known as Alabama Polytechnic Institute

Alliance for Italy, a centrist political party in Italy
Arab Peace Initiative, a peace initiative proposed in 2002 at the Beirut Summit of the Arab League

Active pharmaceutical ingredient, a basic component of any medicine or pharmaceutical drug
Advanced primer ignition, a type of blowback operation for firearms that ignites the primer when the bolt is still moving with the goal of increasing rate of fire and decreasing felt recoil.
Petroleum industry nomenclature deriving from American Petroleum Institute
- API gravity, a measure of the density of petroleum
- API number, a unique identifier applied to each petroleum exploration or production well drilled in the United States
- API unit, a standard measure of natural gamma radiation measured in a borehole
Analytical Profile Index, a miniaturized panel of biochemical tests compiled for identification of groups of closely related bacteria
API oil-water separator
Air Pollution Index, a measure of air quality used in Hong Kong and Malaysia
Armor-piercing incendiary, a type of armor-piercing shot and shell
Atmospheric pressure ionization, a type of ionization in mass spectrometry
Apnea–hypopnea index, an index used to indicate the severity of sleep apnea

Advance passenger information, passenger name record collected by commercial transportation operations
Asian-Pacific Islander
Aviation Preflight Indoctrination, the first major phase of training for a United States Naval Aviator
Announcement in the public interest, an alternate name for a public-service announcement
International Phonetic Alphabet, a system of phonetic notation (known in French as the alphabet phonétique international)