- Do these tools work without installing an app?
- Yes. Every one of them runs in the browser you are already using. There is nothing to install, no account, and no permissions beyond the specific sensor a given tool needs — the level asks for motion, the camera overlay asks for the camera, the analyser asks for the microphone, and the rest ask for nothing at all.
- Do they work with no signal on site?
- Once a page has loaded it keeps working offline, because all the computation happens in the browser and there is no server to call. Basements, plant rooms and steel-framed buildings are exactly where a phone loses signal and where these are most useful, so it is worth opening the page before you go in.
- Is any of my data — sensor readings, photos, audio — uploaded?
- No. This site is entirely static: there is no backend, no database and no upload endpoint to send anything to. Photos are drawn into a canvas in the page, audio frames are analysed and discarded, and orientation readings are converted to an angle on screen. What you log in the price index is stored in your own browser and nowhere else.
- Which tools need a phone rather than a laptop?
- The bubble level and the clinometer need real motion sensors, which laptops do not have — a desktop browser defines the API but never reports a reading, and both tools tell you so instead of showing a frozen bubble. The camera overlay needs a rear camera. The screen ruler, photo takeoff, 3D blueprint and price index all work on any device.
- How accurate are phone-based measurements?
- It depends entirely on which tool. A calibrated screen ruler is accurate to well under a millimetre. A phone used as a level resolves to a fraction of a degree but is limited by the flatness of its own case. A photo takeoff is within a few percent when the shot is square-on and much worse when it is angled. Each tool's page states its own boundary rather than offering a single blanket claim.
- Why does iOS ask permission before the level works?
- Since iOS 13, Safari requires a deliberate user gesture before a web page may read device orientation, because a continuous motion stream can be used to fingerprint a device. The Enable Motion Sensors button is that gesture; there is no way for a page to bypass it, and any site claiming otherwise is not doing what it says.
- Can these replace proper instruments?
- For layout, checking, ordering and getting a number when you do not have the right tool in your hand — yes, and that is most of a working day. For anything that has to be certified, set out structurally, or defended to an inspector, use the calibrated instrument the job calls for. Every tool here states where it stops being trustworthy.
- What happens to the measurement once I have it?
- Each tool links to the calculators that turn its reading into a quantity — a pitch into rafter lengths, a photo dimension into paint or tile, a slab model into concrete volume. That chain is the point: the measurement is only the first half of the job.
