Free tools for developers

A case converter that answers ten ways at once: UPPERCASE, lowercase, Title Case, Smart Title Case, Sentence case, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE.

Spreadsheet column in, comma-separated list out, or the reverse. De-duplicate, sort and quote every value on the way through.

Zip files and folders into one archive with the subfolder paths kept, put an AES-256 password on it if it needs one, or open a .zip and pull out the entry you wanted.

Morse code translator that runs both ways, on 54 characters of the international table, with a Play button that beeps the result at 15 words per minute.

A color converter that reads hex, CSS names, rgb(), hsl() and oklch(), and writes each one back with CMYK and the nearest named color.

CSV to XLSX or an Excel sheet back out as CSV, with the separator read from the data and a wrong split refused before it reaches a workbook. Every cell stays text.

DOCX to HTML with semantic tags and none of Word's span soup. Preview it, copy the markup, or save a styled standalone page.

Convert DOCX to Markdown with ATX headings, hyphen bullets, working links and GFM pipe tables. Copy the output or save it as a .md file under the original name.

Convert a .docx to text and keep only the words, with Word's fonts and spacing left behind. Copy the result or save a .txt that keeps the document's name.

Markdown to PDF that keeps the text selectable and searchable. A4 pages, an 11pt body, code on a light grey panel, links still clickable.

Markdown to Word, done properly: paste your notes and download a real .docx that Word, Google Docs or Pages will edit. Headings map onto Word's own Heading 1 to 6, code lands in Courier New.

Number base converter for binary, octal, decimal and hex, reading input written in any base from 2 to 36. BigInt math, so a 128-bit value converts exactly.

JSON to CSV with the header row built from your keys, or CSV back to JSON with numbers, booleans and nested objects restored.

Convert YAML to JSON, or JSON back to YAML. Output comes back pretty-printed at two-space indent, and a manifest that won't parse gets an error naming the line.

Barcode generator and reader for Code 128, EAN-13, UPC-A, EAN-8, Code 39, ITF-14 and Codabar. Check digits are worked out for you. Download SVG or PNG, batch a list of 200, or read a code off a photo.

A CSS box shadow generator with real sliders: offset, blur, spread and color on every layer, an inset toggle, a live preview card, and one button that copies the declaration.

A CSS gradient generator with a live preview: pick linear, radial or conic, stack up as many color stops as you want, then copy the value into a background rule.

A mock data generator for test tables: names, emails, UUIDs, timestamps and prices, up to 1,000 rows a run. Export as JSON, CSV or SQL INSERTs, and set a seed when the rows have to repeat.

An email signature generator that outputs a single inline-styled HTML table, previewed live, ready to paste into Gmail or Outlook as rich text.

Password generator with two modes: random strings from an 80-character pool, or EFF wordlist passphrases that print their entropy in bits. Length runs to 256, batches up to 100.

A lorem ipsum generator drawing on a 63-word Latin bank, with sentences of 5 to 14 words and up to 100 units per run.

UUID generator for v4, v7 and ULID, up to 1000 ids per press. v4 is 122 random bits; v7 and ULID sort by creation time.

An image color picker with a magnifier: hover to zoom in on the pixels, click the one you want, and copy its HEX, RGB or HSL code.

Convert an image to SVG with the vtracer engine. Three tracing presets, five manual sliders, and a shape count under the result that tells you how heavy it is.

Favicon generator: one image in, a package out. Six PNGs, a multi-size favicon.ico, a manifest with your colours, the head tags, and the 16 seen in a real tab.

Convert video between MP4, MOV, MKV and WebM in your browser. Each target says first whether the clip is repackaged untouched or re-encoded.

An audio visualizer that splits whatever's playing into 1,024 frequency bands and draws each one as a bar, updated every frame.

A tone generator that sounds the moment you press Play: type or slide to any frequency, sweep 20 Hz to 20 kHz, or play white, pink and brown noise.

Stereo to mono, or mono to stereo: pick a direction and get the file back as M4A, Opus, WAV, or FLAC.

A batch audio converter: load MP3, WAV, M4A, OGG or FLAC in any mix, queue as many as you like, and write M4A, WAV, Opus or FLAC back out with a zip at the end.

A Markdown table generator for CSV or spreadsheet rows. Paste them in, the first line becomes the header, and the output is padded so columns line up in the raw text too.

Hash a password with bcrypt at any cost factor from 4 to 31, or paste an existing $2a$, $2b$ or $2y$ hash and check a password against it. The cost and salt are read out of the hash.

A CSV viewer that reads the delimiter off the file and shows its working, types every column so prices sort by value, and downloads the filtered view under the file's own name.

A Parquet viewer that edits as well as reads. Open a .parquet file, walk its schema, page through ten million rows, change a cell, then save real Parquet or export the view as CSV.

Compare two Excel or Google Sheets ranges by pasting them side by side. Changed cells light up, added rows go green, removed rows red.

JSON escape and unescape, plus JavaScript literals, \uXXXX Unicode and backslash sequences. Four modes, both directions.

Convert a curl command to code for 30 targets, including seven separate Node.js HTTP clients.

A JSON formatter with a validator attached: indent at 2 or 4 spaces, minify to one line, or fold a huge payload into a tree.

Convert HTML to Markdown, or render Markdown back to HTML, with the result redrawing as you type. Turndown handles one direction, markdown-it the other, and GFM tables survive both.

A REST client in a tab: build the request, press Send, and when a call gets blocked, read the CORS reason in words plus a server snippet.

A meta tag generator for link previews: nine fields in, up to fifteen lines of head markup out, with the share card and the search result they make drawn above the fields.

Base64 encode text or decode it back, UTF-8 clean, so emoji and accented letters survive the round trip. Files go in too, with an optional data: URI wrapper.

A JWT decoder that splits a token into its three segments, turns iat and exp into readable UTC times, and checks the signature against a secret or public key you paste.

A regex tester that reads the pattern back to you in plain English as it highlights every match and group.

Hash generator for MD5, SHA-1, SHA-256, SHA-384, SHA-512 and CRC32, plus keyed HMAC and a compare box that says outright whether two checksums match.

Paste a cron expression and read it back in plain English, column by column, with the next five run times in UTC, your own zone or the server's.

Encrypt a file behind a password with AES-256-GCM and get back a .tray you can open on any machine. The key is stretched with PBKDF2 at 600,000 iterations.

An HTML entity encoder and decoder in one box: escape & < > " and ', or fold entities back into plain characters.

Convert an image to Base64 and copy it four ways: the data URI, a ready-made <img> tag, a background-image rule, or the bare payload. PNG, JPEG, GIF, WebP and SVG all encode.

A JSON diff that parses both sides before it compares them, so reordered keys count for nothing and every real change arrives as a key path like items[2].price.

Turn a JSON sample into TypeScript interfaces, or switch the output to Go structs with json tags, Zod schemas, or Pydantic models. Name the root type and the nested ones follow it.

Markdown to HTML with the rendered page beside the source. Pipe tables, 36 highlighted languages, Mermaid diagrams, and a markdown.html download.

SQL playground running a real SQLite engine: query a sample schema or open your own .sqlite file, then pretty-print the query in any of eleven dialects.

A subnet calculator for IPv4 and IPv6 that reads a CIDR or an address and mask as you type. Network and broadcast, mask and wildcard, usable host range, plus ip6.arpa and EUI-64 for v6.

A text and code diff checker that goes down to the word: edited lines show only the parts that actually changed, and the comparison exports as a unified .diff.

Turn a Unix timestamp into a readable date or a date back into epoch seconds. Auto-detect sorts 10-digit from 13-digit.

A URL encoder and decoder with the encodeURIComponent versus encodeURI choice made explicit: Component escapes / and & inside a query value, Full URL leaves them standing.

Enter two hex colors and get the WCAG contrast ratio, four pass/fail badges covering AA and AAA at both text sizes, and a live preview at 16px and 24px.

An XML formatter and validator that also converts XML to JSON and back, with errors pinned to the line.

A world clock and time zone converter with a meeting planner that finds the hour everyone is at work, then copies the slot in each city's own local time.