| Application Programming Interface | Computing | API |
| American Petroleum Institute | Business | API |
| Active Pharmaceutical Ingredient | Laboratory | API |
| Air Pollution Index | Meteorology | API |
| Administración Portuaria Integral | Mexican | API |
| Application Program Interface | Other | API |
| Application Program Interface | Aircraft and Aviation | API |
| 1st Reader Passed Parameter File | File Type | API |
| Advanced Policy Institute | Organization | API |
| American Paper Institute | Professional Organizations | API |
| Assistant Inspector of Police | Indian Police Rank | API |
| AMECEA Pastoral Institute | Organization | API |
| Asset Priority Index | Softwares | API |
| Lotus 1-2-3 Printer Driver | File Type | API |
| Anonima Petroli Italiana | Italian | API |
| armor piercing incendiary | Government | API |
| application, programs, and indenture | Government | API |
| aim point initiative | Government | API |
| acquisition program integration | Government | API |
| Atmospheric Pressure Ionization | Meteorology | API |
| Academic Performance Index | University | API |
| automatic payment of invoices | Government | API |
| Arab Planning Institute | Organization | API |
| Alaska Psychiatric Institute | Medical | API |
| acquisition program indicator | Government | API |
| Animal Protection Institute | Non-Profit Organization | API |
| Adobe Acrobat Plug-in | File Type | API |
| Accountable Property Inventory | Accounts and Finance | API |
| Advance Passenger Information | Transportation | API |
| Asian Or Pacific Islander | Country Specific | API |
| Adobe Printer Ink File | File Type | API |
| After Project Initiation | Military and Defence | API |
| Attachment Parenting International | Organization | API |
| air position indicator | Government | API |
| Application Program Interface File | File Type | API |
| AKKARAIPPATTI | Indian Railway Station | API |
| Aromatic Polyimide | Chemistry | API |
| Accountants for The Public Interest | Accounts and Finance | API |
| Apiay | Airport Code | API |
| As Per Instructions | Stock Exchange | API |
| Athletes Performance Institute | Sports | API |
| Aviation Preflight Indoctrination | Military and Defence | API |
