WebDevCalc exists because front-end work is full of small, fiddly calculations that break your focus: converting units, checking a color contrast ratio, generating a meta tag, working out a responsive breakpoint. None of them is hard, but stopping to look up the formula or hunt for a generator you actually trust adds up over a day. This site collects those jobs into fast, single-purpose tools so you can get the answer and get back to building.
The tools cover the recurring jobs that sit between design and shipping. A WCAG contrast checker for verifying that text is actually readable. A robots.txt builder for telling crawlers what to leave alone. A favicon generator that produces the sizes platforms really request. Meta tag and Open Graph generators for controlling how a page appears in search results and shared links. A CSS box shadow generator with a live preview. And a viewport tag builder for getting mobile layout right before any of your CSS runs.
The guides go deeper than the tools do. They cover Core Web Vitals, CSS units and when each one is appropriate, responsive breakpoint strategy, structured data with JSON-LD, and the details of Open Graph tags. Where a tool answers a question, the matching guide explains the system the answer comes from.
Every calculator is grounded in the real web standards. The contrast checker uses the WCAG ratio thresholds, the unit and viewport tools follow the CSS specifications, and the meta and structured-data generators match what MDN and schema.org document. The companion guides link back to those primary sources so you can verify anything yourself.
The reason for citing a source rather than just stating a rule is that front-end advice ages badly. Plenty of widely repeated guidance was correct in 2014 and is wrong now, from meta keywords to disabling pinch zoom to fixed pixel breakpoints matched to specific phones. Naming the specification behind a number lets you check whether it still holds, and it makes it obvious when a guide here has fallen out of date.
These utilities check what can be checked mechanically, which is genuinely useful and also genuinely limited. A passing contrast ratio does not mean your interface is accessible, only that one specific requirement is met on one pair of colors. A well-formed robots.txt does not mean your site is indexed correctly. A generated meta tag does not make a page worth ranking.
Treat each result as one automated check inside a larger job that still needs judgement and real testing, ideally with actual users and assistive technology rather than a score alone.
There are no accounts, no paywalls, and nothing to install. The tools run entirely in your browser, so the colors, URLs, and images you enter never leave your machine. Advertising keeps the site free and covers hosting and the time spent keeping the guides current as specifications change.
WebDevCalc is written and edited by Priya Nair, a front-end developer who builds these utilities and writes every guide from published web standards and documentation such as MDN, the W3C specifications, and web.dev, so each result is something you can trace back to a source rather than take on faith. Each tool started by scratching her own itch first.
Found a bug, or want a tool that does not exist yet? The contact page is the place to say so. Including the inputs you used and the output you expected makes a problem much faster to reproduce and fix.