Check the keys one at a time first
Press each suspect key on its own first. If one key is not observed even by itself, treat that as a single-key problem before testing combinations.
If every key is observed on its own but one or more disappear when you hold them together, the combination itself is the useful clue.
Try the exact combination together
Hold the same keys together in the tester. Keys that reach the browser can appear active at the same time. Repeat the combination a couple of times so you know the pattern is consistent.
If all of the keys appear together, that is positive evidence for that combination in this browser on this computer. It does not prove that every other combination will behave the same way.
Why keys can work alone but not together
Many keyboards scan their keys in a grid rather than using a separate circuit for every key. Some combinations are harder for that grid to report clearly, so the keyboard or its controller may leave out a press rather than risk reporting the wrong one.
The computer, operating system and browser can also affect which key presses reach a webpage. A missing press here tells you what the browser did not receive, but not the exact reason it went missing.
Rollover, in plain English
Rollover is the term used for how a keyboard handles several keys held at the same time. You may see labels such as 6-key rollover or N-key rollover on keyboard specifications.
A browser test should not turn one successful combination into a certified rollover rating. Different combinations can behave differently, and the keyboard itself, connection, operating system and browser can all affect what reaches the page.
Ghosting and blocking are easy to mix up
The word ‘ghosting’ is used inconsistently. Some technical sources use it for a key appearing even though you did not press it. Other support and marketing material uses the word more broadly when a pressed key disappears during a combination.
A keyboard may also deliberately leave out a press when a combination would otherwise be ambiguous. This is often called blocking. Because the browser only sees the events it receives, this site does not automatically label a missing key as ghosting or blocking.
What this browser test can tell you
It can show which key presses reached the browser, which keys are active together and which keys have been observed during the session.
It cannot prove the exact technical cause of a missing press or guarantee that every possible key combination will behave the same way. It also cannot certify a 2-key, 6-key or N-key rollover rating (often written 2KRO, 6KRO or NKRO).
What to try next
- Repeat the exact problem combination in the tester.
- Try the same combination in another ordinary application or browser if it makes sense for those keys.
- If practical, try the keyboard on another compatible computer, or try another keyboard on the original computer.
- If the problem only affects one key even when pressed by itself, use the single-key troubleshooting guide.
- If the combination includes Fn, system keys, media keys or browser shortcuts, check the browser-limitations guide.
Treat the result as evidence, not a certificate
If the same combination repeatedly loses a press across different applications or computers, that points more strongly to a limitation in the keyboard or its connection. Even then, this browser test cannot identify the exact technical cause.
The useful question is not whether the keyboard has earned a label. It is whether the combination you actually need is reported reliably in the environment where you use it.