Developer Tools Calculators

Simplify aspect ratios and calculate matching dimensions.

Estimate video file size from bitrate, duration, audio, and overhead.

Count words, characters, sentences, and estimated reading time from pasted text.

Count characters, characters without spaces, lines, and UTF-8 bytes.

Calculate reading speed in words per minute and estimate time for a target word count.

Calculate screen or image pixel density from resolution and diagonal size.

Generate a CSS clamp() expression from min and max size and viewport widths.

Estimate Base64 encoded length, padding, and size overhead from text or payload bytes.

Estimate JSON byte size, minified size, and parse validity from pasted JSON.

Estimate download time from file size, connection speed, and overhead.

Convert px to rem and rem to px with an adjustable base font size.

Convert em to px and px to em with an adjustable parent font size.

Convert colors between HEX, RGB, and HSL with validation and preview.

Check WCAG-style contrast ratio for foreground and background colors.

Encode or decode URL text safely in your browser with copy-friendly output.

Parse URL query strings into decoded parameters and JSON.

Generate SHA-256 and SHA-1 hashes locally in your browser.

Generate one or more UUID v4 values in your browser.

Validate, pretty print, and minify JSON in your browser.

Convert Unix timestamps to dates and dates to Unix timestamps in seconds or milliseconds.

Validate a five-field cron expression and summarize the minute, hour, day, month, and weekday fields.

Check meta title and meta description character lengths with practical SEO length indicators.

Test a path against pasted robots.txt rules locally in your browser.

Count sitemap URLs, unique URLs, loc tags, and hreflang links from pasted sitemap XML or URL lists.

Test a regular expression against pasted text locally and review matches, flags, and errors.

Encode and decode common HTML entities for snippets, attributes, and content checks.

Decode JWT header and payload parts client-side without verifying the signature.

Convert a JSON array of objects into CSV locally with copyable output.

Convert CSV text into a JSON array locally with quoted-cell handling.

Generate clean URL slugs from titles, headings, product names, or content ideas.

Build campaign URLs with UTM parameters from local input fields.

Estimate QR code module count and printed or digital size from content length and module size.

Check a typed canonical URL string for common formatting issues without fetching the page.

Preview Open Graph title, description, URL, image, and site name from manual fields only.

Generate a copyable meta robots tag from index, follow, snippet, image preview, and archive options.

Create a lightweight JSON-LD schema draft from manual fields for preview and review.

Check repeated words and phrase balance in pasted content without storing the text.