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Methodology

How tools, calculators, and guides on Utilao are actually built and checked, by category. See Editorial Standards for the broader sourcing and correction policy this sits under.

Tool Methodology (PDF, Image, QR, Developer, Text, SEO)

  1. Input handling: each tool validates the input type it claims to accept and rejects or reports on files outside that scope, rather than silently mishandling them.
  2. Processing: server-side tools use established, actively maintained open-source libraries (pypdf, pikepdf/QPDF, Pillow, rembg, qrcode) rather than custom parsing of file formats.
  3. Output verification: before publishing a tool, its output is checked against the operation requested — for example, a resize tool's output dimensions are compared against the requested dimensions, and a compress tool's output byte size and page/image count are compared against the original.
  4. Edge cases: malformed, password-protected, or otherwise unusual inputs are tested where practical, and a tool either handles them or reports a clear failure rather than returning a silently broken file.
  5. Mobile and desktop checks: tool pages are checked on both narrow mobile widths and desktop before publishing, per this project's mobile-first standard.
  6. Known limitations: each tool page states its real limits (file size, format support) rather than an unqualified "no limits" claim — see each tool's own page for current numbers.
  7. Regression checks and corrections: the project maintains an automated regression test suite covering the core PDF/image/QR tools; a reported bad output is retested against the live tool, and confirmed bugs are fixed and covered by a new regression check where practical.

Calculator Methodology (Finance, Health, Everyday)

Every calculator page states, or links to, its formula, required input units, rounding behavior, and key assumptions. Where a formula is externally defined (a government tax bracket, a standard BMI formula, a compounding-interest formula), the source is a government/standards body, primary technical documentation, or an established reference — not a secondary calculator site.

Calculators are estimates, not guarantees. Real-world rates, taxes, fees, lender rules, and individual health factors vary and are not fully captured by a general-purpose formula. Health calculators are explicitly not medical advice and are not reviewed by a medical professional; finance calculators are explicitly not financial, tax, or legal advice. Simple everyday calculators (percentages, tips, dates) carry a proportionally lighter note rather than a heavy disclaimer block, since the stakes of a wrong estimate are much lower.

A calculator's "reviewed" date, where shown, means the formula and page copy were actually re-checked against source material on that date — it is never added without that check happening.

Guide Methodology (Blog)

Guides are written to answer a real question a tool's user is likely to have, using the live tool itself as the primary reference — screenshots, steps, and claims about tool behavior are taken from actually using the current, deployed version, not a spec or an older version. Guides show a published date and a modified date only when materially revised. See Editorial Standards for corrections and sourcing.

Corrections

Report a formula, limit, instruction, or claim you believe is wrong at Contact. It's checked against the live tool or an authoritative source and corrected if the report holds up.