QSA is a three-letter acronym that may refer to:
- Qualified Security Assessor - A certification by the Payment Card Industry (PCI) Security Standards Council
- Queen's Scout Award
- Quaker Social Action
- Qt Script for Applications - scripting engine
- Queen's South Africa Medal for service in the Boer War
- Queensland Swimming Association
- Qatari Student's Association
- Queens of the Stone Age - a band
- Quality Society of Australasia - Which is now the RABQSA International
- Query String Analysis - Apache mod_rewrite rule option.
- querySelectorAll - a JavaScript feature to select elements using CSS selector syntax