Glossary · Testing fundamentals
User acceptance testing
Also called: UAT, user acceptance test, user acceptance tests, end-user testing
Definition
The final testing phase, in which real users or business representatives confirm that the system meets their needs and is ready to accept for release.
User acceptance testing (UAT) is done by the people who will use or own the system, not by the team that built it. Business users run realistic tasks in a production-like environment and decide whether the software does the job they need. A successful UAT ends with formal sign-off, which is often the gate for release or for contractual acceptance from a vendor.
Example
A bank replaces its loan application system. Before go-live, loan officers spend a week in the UAT environment processing realistic applications: a standard personal loan, a joint application, a self-employed applicant with irregular income, and a rejected application that must generate the correct letter. They check that the workflow fits how they actually work, that reports match what managers need, and that nothing forces a manual workaround. Issues are logged, triaged with the project team, and fixed or accepted before sign-off.
UAT vs system testing
| System testing | User acceptance testing | |
|---|---|---|
| Who | QA team | Business users, customers, product owners |
| Question | Does the system meet the specification? | Does it meet our real needs? |
| Basis | Requirements and design | Business processes and acceptance criteria |
| Focus | Defects, edge cases, non-functional checks | Fitness for purpose, usability in context |
A system can pass every system test and still fail UAT, because the specification itself was wrong or incomplete. That is why UAT is the classic example of validation (“are we building the right product?”) rather than verification (“are we building the product right?”).
Types of acceptance testing
- Alpha testing: internal users test at the developer’s site.
- Beta testing: a limited group of external users tests in their own environment.
- Operational acceptance testing (OAT): operations teams check backups, failover, monitoring and deployment.
- Contract and regulatory acceptance: verifies agreed contract terms or legal requirements.
Common mistakes
- Using UAT to find basic bugs. If users hit crashes, system testing was not finished. UAT should focus on fit, not on defects QA should have caught.
- No prepared scenarios or data. Business users need realistic data and clear scenarios, and testers often help write them.
- Leaving it too late. UAT squeezed into the final days before release usually turns into a rubber stamp.