| Acronym | Definition |
|---|
| ZSI | Zertz Scheid Ingenieurgesellschaft (German: Zertz Scheid Engineering Company) |
| ZSI | Zintegrowany System Informatyczny (Polish: Integrated Information System) |
| ZSI | Zoological Survey of India |
| ZSI | Zentrum für Soziale Innovation (Vienna, Austria) |
| ZSI | Zolera SOAP Infrastructure |
| ZSI | Zaurus Software Index |
| ZSI | Zamil Steel Industries (Dammam, Saudi Arabia) |
| ZSI | Zeland Software, Inc. (Fremont, CA) |
| ZSI | Zentralstelle für die Sicherheit in der Informationstechnik (German Information Security Agency) |
| ZSI | Z Solar Inertial |