TAPI is a four-letter abbreviation, and may refer to:
- Telephony Application Programming Interface, an API which enables PCs running Microsoft Windows to use telephone services
- Turkmenistan-Afghanistan–Pakistan–India pipeline, a proposed natural gas pipeline
- Teva Active Pharmaceutical Ingredients, a stand-alone business unit of Teva Pharmaceutical Industries limited
- TAPI-0 and TAPI-1, inhibitors used in biochemistry
