SPI may stand for:
In organizations:
- Shotmed Paper Industries, an Egyptian paper manufacturer
- Simulations Publications, Inc., an American publisher of board wargames
- Sony Pictures Imageworks, a visual effects and animation company
- SPi Technologies, a business outsourcing provider founded in the Philippines
- Stream Processors, Inc. Stream Processors, Inc. a fabless semiconductor company making parallel processors for embedded markets.
- Sisters of Perpetual Indulgence, international LGBT non-profit group
- Society for Philosophical Inquiry, a non-profit organization promoting discussion of philosophy
- Society of the Plastics Industry, a U.S. trade association
- Software in the Public Interest, a non-profit organization promoting free and open-source software
- Software Patent Institute, an American non-profit assisting in the correct assignment of software patents
- St. Pascual Institution, former name of Colegio de San Pascual Baylon, a school in Obando, Bulacan, Philippines
- St. Paul's Institution, Seremban, secondary school in Malaysia
- Sveriges Pensionärers Intresseparti, or Swedish Senior Citizen Interest Party, a political party in Sweden
In finance:
- SPI 200 futures contract, the benchmark equity index futures contract in Australia
- Swiss Performance Index, most closely followed stock index in Switzerland
In technology:
- SCSI Parallel Interface, in physical data transfer, a parallel electrical bus interface
- Serial Peripheral Interface Bus, a synchronous serial data link standard that operates in full duplex mode
- Security Parameter Index, in computer networking, an identification tag added to the header
- Service provider interface, a software mechanism to support replaceable components
- Software Process Improvement, an initiative of the Data & Analysis Center for Software
- Stateful packet inspection, the process used by a firewall to keep track of the state of network connections
- System Packet Interface, family of interfaces from the Optical Internetworking Forum
- SPI-3, a system packet interface designed to be used in systems that support OC-48 SONET interfaces
- SPI-4.2, a system packet interface designed to be used in systems that support OC-192 SONET interfaces
- SharePoint Project Item, a collection of project files in Microsoft SharePoint.
In other:
- Abraham Lincoln Capital Airport, a Springfield, Illinois airport with IATA code SPI
- Spi-calculus, a proposed extension of the Pi-calculus