Developer utilities by Gary Le Sueur
Generate UUIDs, short IDs, NanoIDs, and ULIDs with one click.
Encode text to Base64 or decode Base64 back to text.
Percent-encode text for URLs or decode encoded strings.
Convert special characters to HTML entities and back.
Generate placeholder text in paragraphs, sentences, or words.
Convert between Unix timestamps and human-readable dates.
Count characters, words, sentences, lines, and bytes in your text.
Upload a square PNG and get every favicon size your site needs.
Upload a PNG and get every icon size a Chrome extension needs.
Inspect Open Graph tags and preview how your link looks on social platforms.
Pretty-print and validate JSON with clear error messages.
Decode JWT headers and payloads — no secret needed.
Convert colours between hex, RGB, and HSL with a live preview.
Check text and background contrast ratio against WCAG 2.1 AA and AAA thresholds.
Generate SHA-1, SHA-256, SHA-384, and SHA-512 hashes from text.
Test regular expressions with live match highlighting and capture groups.
Compare two blocks of text and see additions and deletions highlighted.
Convert between px, rem, em, vh, and vw with configurable base values.
Spot invisible and non-printing characters hiding in your text.
Write Markdown and see a live rendered preview side by side.
Batch compress images with side-by-side preview and ZIP download.
Decode cron expressions into plain English and preview upcoming run times.
Convert CSV to JSON or JSON arrays to CSV with comma, tab, or semicolon delimiters.
Format and validate YAML, convert YAML to JSON, or JSON to YAML — all in the browser.
Convert SVG files to rasterised PNG or JPEG at any size.
Enter text or a URL to generate a QR code. Download as SVG or PNG.
Paste a className string and get it back sorted in the recommended Tailwind order.
Pick dimensions, colours, and overlay text — get a downloadable placeholder PNG or a data URL.
Enter a date and see it formatted in ISO 8601, RFC 2822, SQL, relative, and more.
Pick a date and time, then see it displayed across multiple time zones.
Calculate the duration between two dates, or add a duration to find an end date.
Add or subtract days, weeks, months, or business days from any date.
Find the ISO week number for a date, or look up the date range for a given week.
Paste text containing Unix timestamps and see them converted to dates inline.
Convert between decimal, hexadecimal, octal, and binary. Supports large integers.
Convert between bytes, kilobytes, megabytes, and more — in both SI and binary units.
Calculate aspect ratios from dimensions, or find a missing dimension from a ratio.
Toggle permissions or enter a number to see the chmod breakdown.
Enter CIDR notation to see the network details, host range, and subnet mask.
Paste a title or sentence to generate a URL-friendly slug.
Convert text between camelCase, PascalCase, snake_case, kebab-case, and more.
A searchable reference of all HTTP status codes with descriptions and use cases.
Generate secure random passwords with configurable length and character sets.
Generate cryptographically random secrets and tokens for API keys, JWT secrets, and more.
See everything your browser reveals — user agent, screen, GPU, network, and more.
Paste a string to see each character with its numeric code point underneath.
Combine multiple PDF files into a single document — all in the browser.
Split a PDF into individual pages or custom ranges. Download as a ZIP.
Drag and drop to reorder pages in your PDF, then download the result.
Select and remove unwanted pages from a PDF — all in the browser.
Pick specific pages from a PDF and download them as a new file.
Rotate individual pages or all pages in a PDF by 90°, 180°, or 270°.
Change the page size of your PDF to A4, Letter, or custom dimensions.
Reduce PDF file size by re-saving and stripping unused objects — all in the browser.
Bake form fields and annotations into page content, making them permanent.
View, edit, or strip metadata (title, author, keywords) from a PDF.