User acceptance testing
User acceptance testing, or UAT, is the activity in which the buyer's own users check a release against agreed acceptance criteria, in an environment close to production, before the buyer accepts it. It comes after the supplier's own testing and answers a different question: does this work for us, not does it run without crashing.
Submit a project Write your acceptance criteriaReviewed by Huy Nguyen (David), CEO · Updated 21 Oct 2026 · 3 min read
This term is one of the entries in the OutsourcingVN glossary of words buyers meet while preparing to accept a milestone.
Why does user acceptance testing matter?
A release can pass every automated check a supplier runs and still fail the business if nobody who actually does the daily work has tried it against a real scenario. OutsourcingVN is operated by Netbase JSC, and the reason UAT sits with the buyer's own users rather than the supplier's testers is that only the people who will use the system day to day can judge whether it genuinely fits how the work actually happens, as opposed to how it was specified on paper. Skipping UAT and going straight from the supplier's sign-off to launch is how a technically correct release still arrives unusable.
What is an example of user acceptance testing in practice?
A clinic commissions a booking system and its own reception staff run UAT before go-live: they book, reschedule and cancel real-looking appointments, check a double-booking is rejected, and confirm a cancelled slot reopens correctly. One tester finds that cancelling an appointment does not free the slot for same-day booking, which the supplier's own tests had not covered because it never looked for that exact sequence. The release is held back until that row passes, and the rest of the clinic's criteria pass on first try.
What are the common misreadings of user acceptance testing?
UAT is not the same as the supplier's system or regression testing: those check that the software behaves correctly against its specification and that nothing already working has broken, run by the people who built it; UAT checks that the result fits the buyer's actual work, run by the people who will use it. It is also not the criteria themselves: see acceptance criteria for that definition, since UAT is the activity of checking a release against criteria that were written and agreed before testing began, not the list of conditions being checked.
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Common questions
The buyer's own users or a nominated business representative, not the supplier's test team, since the point is a check by the people who will rely on the result.
It is logged as a defect against the specific criterion it fails, fixed by the supplier, and re-tested on that row before the milestone is accepted.
Which decisions does user acceptance testing affect?
Writing the criteria UAT will check against is the subject of the software acceptance criteria guide, which this activity assumes is already done before testing starts. Once a release passes UAT, the software release readiness checklist covers what else must be true before it actually goes live. When you know who on your side will run this check, describe it and Netbase will respond through Netbase's own outsourcing-services platform; submit a project when you are ready.