Purpose and responsibility
ProtractorOnline.org provides browser-based visual angle measurement, calculation, practice, and printable tools. The site is maintained as an independent technical resource. It does not claim a professional accreditation, a large editorial team, or usage figures that cannot be verified.
Tool behavior, formulas, page metadata, links, and representative interactions are checked in the repository before a production build. Readers can report a calculation error, unclear instruction, accessibility problem, or broken workflow by email; corrections are evaluated against reproducible examples.
How the tools and content are checked
- Geometry and slope functions have automated unit tests, including boundary and conversion cases.
- Static build tests check canonical URLs, unique titles and headings, sitemap membership, internal links, and parseable JSON-LD.
- Content audits measure repetition and keyword use as warning signals; an editor must still judge whether wording is useful and natural.
- Browser smoke checks cover the main measurement modes and responsive layouts before release.
Browser-side file handling
- Images use temporary browser object URLs and Canvas rendering.
- PDF.js loads on demand and renders the selected page locally.
- Exports are assembled in the active browser session.
- The measurement workspace does not transmit source files, points, annotations, or exports to analytics.
Report an error
- Email [email protected] with the page URL and the expected result.
- For a tool bug, include reproducible steps, browser and device details, and a non-sensitive sample when possible.
- For a content correction, identify the exact sentence and provide a reliable source or worked calculation.
- Never send confidential plans, private records, passwords, or files you do not have permission to share.
Scope
The site explains and performs visual geometry tasks, but it is not an engineering firm, surveying service, medical provider, standards body, or certification authority. See the Disclaimer and Measurement Methodology for the practical boundaries of results.