About WhichBeep
WhichBeep is a free browser tool that uses your phone's microphone to work out which smoke or CO detector in your house is the one chirping. It was built after one too many 3am hunts through a hallway, holding a ladder, waiting for the next beep.
Who writes these guides
WhichBeep is written and maintained by Michael Palermiti, a software product lead who built the tool for his own house first. He is not a firefighter, an electrician, or a certified fire-protection engineer — which is exactly why nothing on this site is written from memory or personal 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 rule for this site is narrow and absolute:
- Manufacturer documentation only.Beep patterns, chirp meanings, battery specifications and reset procedures come from the manufacturer's own support pages, product pages and manuals — Kidde, First Alert and the rest — or from a federal regulator such as the CPSC. Never from forums, blogs, retailer listings, or inference from a similar model.
- Cited inline, on the page. Every pattern and procedure carries a numbered citation to the document it came from, listed at the bottom of the page with the date we last opened it.
- The manual wins.When a manufacturer's documentation contradicts something already published here, the page gets corrected — we do not split the difference or leave the old claim standing next to the new one.
- Unsourced claims get removed, not softened. If a specific claim cannot be tied to a manufacturer document, it comes off the page. Several did.
Each guide shows the date it was last reviewed against its sources. That date only moves when someone has actually re-read the page against the manuals — not when the site is redeployed.
Your manual beats this website
Manufacturers change patterns between model generations, and a guide written about a brand cannot be right about every unit that brand has ever shipped. The model number is on a sticker on the back of the detector, and the manual for that exact model is the authority. If your manual disagrees with this site, follow your manual — and please 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. When a detector is identified, the results page may link to replacement batteries on Amazon as an Amazon Associate, which earns a small commission on qualifying purchases at no extra cost to you. There is also a tip jar. No manufacturer pays for placement, and no brand has any say in what these guides say about its products — including the corrections.
Privacy
The audio never leaves your phone. All the sound processing runs in your browser — there is no server to upload a recording to, and nothing is stored.
Corrections and contact
Found something wrong, or have a manual that contradicts a page here? Send it over — a link to the manufacturer document is the fastest way to get a page changed. hello@whichbeep.com
Find the detector that's chirping
Walk your house with your phone. WhichBeep compares the chirp at each detector and tells you which one to take down.
Try WhichBeep