About WhichBeep
A free browser tool that uses your phone's microphone to find which smoke or carbon monoxide detector is the one chirping. It was built after one too many 3 AM hunts down a hallway, ladder in hand, waiting for the next beep.
Who writes these guides
WhichBeep is written and maintained by Michael Palermiti, a software product lead who built it for his own house first. He is not a firefighter or an electrician — which is exactly why nothing here is written from memory or opinion.
How the guides are sourced
A beep pattern is a safety instruction: get it wrong and someone ignores a carbon monoxide alarm, or pulls down a working detector. So the rules are narrow.
- Manufacturer documentation only. Patterns, meanings and procedures come from the manufacturer's own manuals and support pages — Kidde, First Alert and the rest — or a federal regulator such as the CPSC. Never from forums, blogs, retailer listings, or inference from a similar model.
- Cited on the page. Every pattern and procedure carries a numbered citation to its source, with the date it was last checked.
- The manual wins. When a manufacturer document contradicts a page, the page is corrected — we do not split the difference or leave the old claim standing next to the new one.
- Unsourced claims come off. If a claim cannot be tied to a manufacturer document, it is removed, not softened.
Each guide shows two kinds of date. “Last updated” is when its wording last changed. Every source in its list shows when that manual was retrieved and read. Neither moves when the site is redeployed.
Your manual beats this website
Patterns change between model generations. The model number is on a sticker on the back of the detector, and that model's manual is the authority. If it disagrees with this site, follow your manual — and tell us, so we can fix the page.
If a detector is sounding a continuous alarm, or a carbon monoxide alarm is sounding at all, treat it as real: get everyone outside and call 911 from outside. Do not stop to read a website.
How WhichBeep makes money
The tool is free and there are no ads. The results page links to replacement batteries on Amazon. As an Amazon Associate, WhichBeep earns from qualifying purchases, at no extra cost to you. There is also a tip jar. No manufacturer pays for placement or has any say in what the guides say about its products.
Privacy
The audio never leaves your phone. All sound processing runs in your browser, and nothing is recorded or stored. Privacy & Terms has the details.
Corrections and contact
Found something wrong, or have a manual that contradicts a page? A link to the manufacturer document is the fastest way to get it changed: hello@whichbeep.com
Find the detector that's chirping
Walk your house with your phone. WhichBeep tells you which one to take down.