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Smart home tools that answer one question properly
Every tool here exists because the answer to a specific, common question was buried in a forum thread, a PDF, or a manufacturer's page that only wanted to sell you their version. Each one works in your browser, shows its calculation, and doesn't ask you for anything.
The tools
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Zigbee vs Wi-Fi channel planner
Zigbee and 2.4 GHz Wi-Fi share the same band, and Wi-Fi is far louder. Enter the Wi-Fi channels in use around you and get the Zigbee channel with the most clear space, with the frequency overlap drawn out.
"Which Zigbee channel should I use?"
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Thermostat C-wire checker
Tick the lettered terminals behind your old thermostat. Find out whether you have a common wire, what HVAC system you actually have, and what your options are if there's no C — without a brand trying to sell you a thermostat.
"Do I have a C-wire?"
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Video doorbell power checker
Most video doorbell reboot problems are a VA rating problem, not a voltage problem. Checks capacity, calculates voltage lost down the wire run, and tells you what your chime type needs.
"Is my transformer enough?"
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Smoke & CO alarm planner
Describe your floors, bedrooms and appliances. Get a count, a room-by-room placement list, and the clearance rules that decide whether an alarm works or just goes off whenever you cook.
"How many do I need, and where?"
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Atmos passthrough checker
Dolby Atmos fails silently — everything connects, sound works, and you're listening to Dolby Digital 5.1. Traces your signal path and tells you which format actually survives it, and usually which single cable to move.
"Am I really getting Atmos?"
Why these are free, and what that means
There's no account, no email capture and no affiliate link in any of them. They run entirely in your browser — nothing you type is sent anywhere, because there's no server to send it to. You can use them offline once the page has loaded.
Each one shows its working. Where a result comes from a formula, the formula is on the page. Where it comes from a published standard, the standard is named. If you disagree with an answer you can check it yourself, which is the point — a tool you can't verify isn't much better than a guess.
What they can't do
These are planning aids, not inspections. They model the specific thing they describe and nothing else. The Zigbee planner doesn't know about your walls; the doorbell checker doesn't know your transformer is thirty years old and underperforming its label; the alarm planner doesn't know your local fire code. Where a result matters for safety or for something expensive, treat it as the starting point for a conversation with someone who can see the actual installation.
Something wrong, or something missing?
If a tool gives you an answer you think is incorrect, that's worth knowing about — the calculations are documented specifically so errors can be found. Tools get added when a question turns out to be common and the existing answers are poor.