A browser keyboard tester can reveal missing, stuck or duplicated keys without installing software.
Test press and release
Press each key once and confirm that it lights on keydown and returns on keyup.
Check combinations
Test common modifiers separately and in combinations. Some keyboard matrices cannot report every simultaneous set.
Separate hardware and layout
The printed character, operating-system layout and physical scan code are related but not identical.
Sources and editorial notes
Published: 2026-07-11 · Updated: 2026-07-11