ToolMelt — 21 fast, private utilities that run entirely in your browser.
Convert and preview documents and files.
Convert PDF pages to PNG or JPEG images at up to 300 DPI, or combine JPG/PNG images into one PDF. Free, no sign-up — your files never leave your browser.
Free online Markdown editor with live HTML preview. Supports headings, lists, code blocks and GitHub-style basics, with HTML export. No sign-up needed.
Count, convert, compare and generate text.
Free online word counter. Count words, characters, sentences and paragraphs in real time, plus reading and speaking time estimates. No sign-up needed.
Convert text between UPPERCASE, lowercase, Title Case, Sentence case, camelCase, PascalCase, snake_case and kebab-case. Free online tool, instant results.
Compare two texts line by line and see additions and removals highlighted. Free online diff checker with unified view and change statistics. No sign-up.
Generate Lorem Ipsum placeholder text — paragraphs, sentences or words, with the classic opening, copied as plain text or HTML. Free, instant, no sign-up.
Format, encode, decode and inspect structured data.
Free online JSON formatter, validator and minifier. Beautify JSON with 2 or 4 spaces, find syntax errors with line numbers, and copy the result. No sign-up, data stays in your browser.
Encode text to Base64 and decode Base64 back to text online. UTF-8 safe, URL-safe option, instant results, no sign-up. Your data never leaves your browser.
Encode or decode URLs and query strings online. Supports component and full-URL modes (encodeURIComponent vs encodeURI) — free, instant, in your browser.
Convert special characters to HTML entities and decode entities back to text. Named and numeric entities, non-ASCII option, instant results, in your browser.
Decode JWTs online and inspect the header, payload and claims instantly. Expiry and issued-at shown in human time. Free, private — tokens are decoded locally in your browser, never sent anywhere.
Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes from any text online. Instant results as you type, uppercase option, one-click copy. Free and private.
Everyday helpers for developers: regex, CSS, cron and timestamps.
Free online regex tester with live match highlighting, capture groups, flag toggles and find-replace. Debug JavaScript regular expressions in your browser.
Minify CSS to reduce file size or beautify it for readability. See byte savings instantly and copy the result in one click. Your CSS never leaves your browser.
Parse any 5-field cron expression into plain English and see the next run times instantly. Field breakdown, examples and validation. Free, runs in your browser.
Convert Unix timestamps to human-readable dates and dates back to timestamps. Seconds and milliseconds, UTC and local time, ISO 8601 output.
Create passwords, UUIDs and QR codes in one click.
Generate strong, random passwords online. Choose length, symbols and character sets, see entropy and strength, copy in one click. Free and private.
Generate random v4 UUIDs (GUIDs) online. Bulk up to 100, uppercase or hyphenless formats, one-click copy. Free, no sign-up, runs locally in your browser.
Free online QR code generator. Type text or a URL, choose a size and error-correction level, then download as PNG or SVG. No sign-up; runs in your browser.
Convert units and colors between formats.
Convert units online: length, weight, temperature, area, volume, speed, digital storage. Live results as you type, conversion table included. Free, no sign-up.
Convert colors between HEX, RGB and HSL online. Live preview swatch, native color picker, one-click copy of CSS values. Free, instant, works in your browser.
In-depth reference articles that pair with the tools.
Quick-reference cron cheat sheet: the 5 fields, every operator (* , - /), 30 copy-paste examples with plain-English meanings, and the pitfalls that bite most.
How a JSON Web Token works: header, payload and signature segments, base64url encoding, the standard claims, and why decoding a JWT is not verifying it.
The 10 most common JSON.parse failures — trailing commas, single quotes, comments, NaN — each shown broken and fixed, plus how to read the line and column.
Regex cheat sheet: character classes, anchors, greedy vs lazy quantifiers, capture groups, lookarounds, flags g i m s u, plus 5 copy-ready patterns.
A Unix timestamp counts seconds since 1 January 1970 UTC. Learn why 1970, seconds vs milliseconds, leap seconds, the 2038 problem, and code snippets.
Markdown cheat sheet with syntax vs result tables: headings, bold, lists, links, code blocks, GFM tables, task lists and footnotes, plus 5 copy-ready snippets.
Hex vs RGB vs HSL explained: what each CSS color model encodes, a step-by-step hex to RGB to HSL conversion example, and when to use each format.
Camel case vs snake case vs kebab case compared: rules, examples, and where each naming convention is standard in JavaScript, Python, CSS, URLs and constants.
Base64 explained: what Base64 encoding is, how 3 bytes become 4 characters, the 33% size overhead, URL-safe Base64, and why Base64 is not encryption.
Is MD5 secure? MD5 vs SHA-256 explained: digest sizes, speed, the collision attacks that broke MD5 and SHA-1, and which hash algorithm to use in 2026.
UUID versions explained: anatomy of the 8-4-4-4-12 format, v4 vs v7 compared, collision math, database key performance, NIL UUIDs, and which version to pick.
Convert PDF to JPG or PNG online for free. Learn which DPI to use (72, 150 or 300), when PNG beats JPG, and how to combine images back into a PDF.
Percent-encoding reference: the RFC 3986 reserved characters table, encodeURIComponent vs encodeURI examples, the %20 vs + space problem, and common bugs.
How many words per page? ~250 double-spaced, ~500 single-spaced. Convert 500-5000 words to pages, speech minutes and reading time with quick tables.
Password entropy explained with real math: how bits are calculated, why length beats complexity, entropy tables for 8-20 chars, and diceware passphrase tips.
HTML entities cheat sheet: special character codes for &, <, >, quotes, dashes, curly quotes, arrows, math and currency symbols — named, decimal and hex.
Lorem ipsum explained: what the standard passage says, its real origin in Cicero's 45 BC text de Finibus, and why designers use placeholder text.
Quick links to the most-visited quick-reference pages — every unit pair, CSS color and timestamp on the site has its own page like these.
Every tool on ToolMelt is a small, focused web page that does one job well — formatting JSON, converting PDF pages to images, generating passwords, testing regular expressions and more. Because all processing happens locally with JavaScript, the tools are fast, work on any device, and keep your data private: nothing you type or drop in is ever uploaded to a server.
100% client-side, no uploads, no tracking. Whatever you paste never leaves your browser.
No queues, no sign-up, no watermarks. Results appear as you type.
Each tool has its own URL under a subdirectory — link straight to the one you need.
Yes. Every tool on ToolMelt is completely free, with no sign-up, no watermarks and no usage limits.
No. All 21 tools are ordinary web pages that run entirely in your browser — on desktop and on mobile.
On your device. Every tool works 100% client-side with JavaScript, so whatever you paste or drop into a tool never leaves your browser. See the privacy policy for details.
Yes. Each tool lives under its own path (for example /json-formatter/) with its own bookmarkable URL — share or link directly to any of them.