SNI may refer to:
- Seneca Nation of Indians
- Server Name Indication, a feature that, among other things, allows for SSL-enabled name-based virtual hosts
- Serviço Nacional de Informações, the National Intelligence Service of Brazil
- Showtime Networks, Inc.
- Sistema Nacional de Investigadores (SNI), Mexico's national system of researchers.
- Soviet Naval Infantry
- Microsoft SQL Server Networking Interface
- Substitution nucleophilic internal, a chemistry reaction mechanism
- Swedish Standard Industrial Classification, a Swedish economic classification system
- Swiss Nanoscience Institute
- Sports Network Incorporated