Questions, answered plainly.
Do I need to sign up or install anything?+
No. Open /protractor and it's ready to use immediately — no account, no download, no browser extension.
Does my photo get uploaded anywhere?+
No. Images you drop, paste, or upload are decoded and drawn directly in your browser tab — they're never sent to a server. Closing the tab clears everything, since there's no account or storage involved.
How accurate is it?+
As accurate as your ray placement. Zoom in on the canvas before dragging a ray endpoint for finer control, and use angle snapping if you're measuring a known increment. For safety-critical or load-bearing work, double-check with a physical protractor.
Does it work well on my phone?+
That was the main thing we set out to fix. Dragging a ray or pinch-zooming the canvas uses the same touch handling on a phone as it does with a mouse on desktop, with larger touch targets and a magnified preview while you drag, so your finger doesn't block the point you're placing.
Can I measure more than one angle at a time?+
Yes — add as many protractors as you need to the same canvas or image. Each one moves, rotates, and snaps independently.
What can I export?+
A PNG image of exactly what's on the canvas, and a CSV with each protractor's center point, ray endpoints, and angle in degrees — useful for a report, a spreadsheet, or just a record of what you measured.
What if I rotate or flip my image after I've already measured something?+
Your protractors rotate and flip along with the image, so they stay pointing at the same spot in the photo. Loading a completely different image, though, doesn't try to reposition protractors from the previous one — it's simplest (and most predictable) to add fresh ones for a new image.
Is a ruler or angle-classifier mode coming?+
An on-screen ruler mode and a spirit/bubble level (using your device's orientation sensors) are both on the roadmap. The protractor is the fully-built tool today.