🧩 Developer & Data Tools

22 browser-local tools · page 1 of 1

Developer & Data Tools. The workbench half of the toolbox: a JSON formatter that reports the exact line and column of a syntax error and preserves key order, a JWT decoder that shows the header and claims without signing anything, hashes from MD5 to SHA-512 over text or a whole file, Base64 both ways with URL-safe output, UUID v4 and v7 generation with a decoder, a cron explainer that catches the day-of-month versus day-of-week trap, a regex tester with live match highlighting, CSV to JSON, a word diff, a URL parser and a subnet calculator.

22 tools on this shelf · 22 listed below

🔐Password GeneratorTrue random passwords from your browser’s cryptographic generator, with honest entropy maths — the password never touches our server. 📍What Is My IP?Your public address, the ISP-level location databases infer from it, and every browser field a website can read — shown openly, nothing stored. 🧩JSON FormatterFormat, minify and validate JSON with the exact line and column of a syntax error; large numbers and key order survive because it scans instead of re-parsing. 🔑Checksum & HashMD5, SHA-1, SHA-256, SHA-384 and SHA-512 of text or a whole file at once — verify a download against its published checksum privately. 🔁Base64 EncoderUTF-8-correct Base64 both ways, URL-safe output, and a file turned into a data: URL — with the honest note that encoding is not encryption. 🆔UUID GeneratorRandom v4 and time-ordered v7 identifiers in bulk, plus a decoder that shows the version, variant and any embedded timestamp. ⏰Cron ExplainerAny five-field cron schedule in plain English with its next ten runs, every field validated — including the day-of-month/day-of-week OR trap. 🔍Regex TesterTest JavaScript regular expressions with live match highlighting, group inspection, and a common-pattern library (email, URL, IPv4, dates). 📊CSV ViewerPaste CSV or TSV and see it as a formatted table instantly. Convert to JSON, copy or download — RFC 4180 compliant, all local. 🔀Text DiffCompare two blocks of text line-by-line or word-by-word: additions, deletions and unchanged parts highlighted instantly. 🔗URL ParserBreak a URL into protocol, host, port, path, query parameters and fragment. Encode and decode components side-by-side. 🔣Character ReferenceInspect any character: Unicode code point, HTML entity, UTF-8 bytes and UTF-16 unit count — a quick-reference for invisible bugs. 🔣HTML EntitiesEncode text so it survives an HTML parser and decode entity soup back, using the browser's own decoding table — nothing sent anywhere. 🎫JWT DecoderRead any JWT's header and claims with expiry dates made human — and an honest refusal to pretend an unsigned token is verified. 📏CSS Unit Converterpx to rem to pt with your real root font size, and an honest note about the one unit (em) that depends on context this page cannot see. 📝Markdown to HTMLA Markdown-to-HTML converter that escapes angle brackets before it formats, so no script tag ever survives the trip — paste, copy, done, nothing uploaded. 🔤Case ConverterPaste any identifier — getUserID, http-request, API_KEY_2 — and get all nine naming conventions from one tokenisation, camelCase humps included. 🕸️Subnet CalculatorThe full IPv4 breakdown of any CIDR — network, broadcast, first and last usable address, mask and wildcard, and the next block in the allocation, by pure arithmetic. 🔐Password StrengthEntropy bits instead of a coloured bar: the character pool, the dictionary and-pattern penalties, and what a GPU cracking rig needs. ⌨️Keyboard TestPress every key and see every register — the two-minute health check for a secondhand laptop, a borrowed keyboard or a suspect switch. 🏷️EAN-13 BarcodeGenerate real EAN-13 barcodes from 12 digits — the check digit computed with the official 1,3 weights and the bars drawn straight onto a canvas, with the encoding table on the page. ✂️Slug GeneratorCrème Brûlée becomes creme-brulee — accents stripped properly, symbols spelled out before they are dropped, and the length cut never leaves a dangling dash.

How these tools work

Files are the point. Anything you paste, hash, split or convert is read by your browser and never uploaded, so a production config, an auth token, a customer CSV or a build artefact can be inspected here without deciding whether a third-party server can be trusted with it. Each page states which standard or algorithm it follows — RFC 4180, RFC 4648, RFC 4122, WCAG — instead of leaving you to guess.

Part of Everyday Tools — 22 of 1136 tools sit here. Other shelves: City-to-city Distances, Coordinates & Position, Antipodes, Numbers & Maths, Money, Rates & Shopping, Health, Body & Fitness, Date & Time, Developer & Data Tools, Text, Words & Writing, Study & Learning, Colour, Images & Files, Everyday Tools. Looking for something specific? Search the whole toolbox.