Developer tools that run entirely in your browser

Format, validate and minify JSON. Precise error location with row and column, plus syntax highlighting.

Escape and unescape JSON strings — quotes, control characters and \uXXXX.

Render JSON as a collapsible, navigable tree.

Convert between JSON and XML. Nested objects are wrapped under a configurable root element.

Convert between JSON and YAML 1.2 with live validation and row/column error locations.

Run JSONPath / jq-style queries against a JSON document and highlight every match.

Validate JSON against a JSON Schema (Draft-07 / 2019-09 / 2020-12) with per-field violations, or infer a schema from a sample.

Generate fake JSON data with @faker-js/faker — pick preset fields or author a template, choose a locale, and export as JSON or CSV.

Compare two JSON documents and highlight structural differences.

Convert a JSON array into an Excel .xlsx workbook with SheetJS and download it.

Flatten an array of JSON objects into CSV with RFC 4180 quoting. Download the result as a file.

Generate TypeScript, Java, Go and C# entity types from JSON. Infers nested objects and arrays.

UTF-8 safe Base64 encoding and decoding, with an optional URL-safe variant.

Percent-encoding for URL components and full URLs (RFC 3986).

Encode and decode HTML entities — named, decimal and hexadecimal.

Convert between text, UTF-8 hex bytes and Unicode code points.

Compress or decompress text with gzip, deflate or zlib. Output as Base64 or Hex with a before/after size comparison.

Convert internationalized domain names between Unicode (中文.com) and ASCII Punycode (xn--). Handles email addresses and a per-label breakdown. RFC 3492.

Compute SHA-1/256/384/512 via Web Crypto and MD5. Hex or Base64 output.

Compute HMAC-SHA-1/256/384/512 signatures with Web Crypto. Hex or Base64 output, all in your browser.

Hash a password with bcrypt (adaptive cost), or verify a plaintext against an existing $2a$ / $2b$ hash. Adjustable cost, calibrated timing — all in your browser.

Generate time-based (TOTP) or counter-based (HOTP) one-time passwords from a Base32 secret or an otpauth:// URI. Live countdown and a scannable QR code — all locally in your browser.

AES-GCM symmetric encryption with a PBKDF2-derived key, random salt and IV. Password-based.

RSA-OAEP encryption and RSASSA-PKCS1-v1_5 signing with Web Crypto. Generate a key pair or paste a PEM key.

Generate cryptographically secure random passwords with crypto.getRandomValues.

Generate cryptographically secure random salts and tokens as hex or Base64, using crypto.getRandomValues.

Convert between Unix timestamps and human-readable dates across time zones.

Build, validate and explain cron expressions. Computes the next trigger time (UTC).

Convert integers between bases 2–62 with BigInt, so even very large numbers keep full precision.

Format numbers with Intl.NumberFormat — thousands separators, scientific notation, precision and currency, for any locale.

Convert between units of length, area, volume, temperature, data storage and time — pure coefficients, 100% offline.

Validate national ID numbers from 15 countries: check format and checksum locally for China, US, UK, Canada, Australia, India, Japan, Korea, Russia, France, Germany, Spain, Portugal, Bangladesh and Saudi Arabia. No lookup, no storage.

Convert between FLOPS/TOPS AI compute units. FLOPS and TOPS measure different operations and aren't directly convertible.

Compute network address, broadcast, netmask, host ranges and class for IPv4/IPv6 CIDR blocks using BigInt.

Convert Chinese characters (Hanzi) to pinyin in three tone forms at once — tone marks, tone numbers, and tone-less. Detects polyphones and supports surname mode.

Convert Chinese text between Simplified and Traditional with per-character diff highlighting. Choose general, Taiwan (regional vocabulary like 内存→記憶體), or Hong Kong variants. 100% client-side via opencc-js.

Compare current times across multiple timezones side by side and plan cross-region meetings. Pick a reference time in one zone and every other zone updates in sync; working hours (9–18) are highlighted.

Test JavaScript regular expressions with match highlighting and capture groups.

Convert between HEX, RGB and HSL with a live preview and palette.

Convert a curl command into JavaScript fetch, axios, Python, Go, Java and HTTPie — live, with multi-language tabs.

Convert between chmod octal, symbolic and a 3×3 permission matrix — live, three-way synced.

Parse, compare and range-check semantic versions — supports ^, ~, >=, <, x-ranges and ||.

Press any key to inspect its KeyboardEvent fields live — key, code, keyCode (legacy), which, modifiers and location, with a recent-press history.

Validate card numbers with the Luhn checksum and detect the issuer brand (Visa, Mastercard, Amex, UnionPay, Discover). Runs entirely in your browser.

Generate cryptographically random UUIDs (RFC 4122 v4) using crypto.randomUUID.

Decode a JSON Web Token (header, payload) and inspect its expiry and signature. Decoding only — the signature is not verified.

Parse a User-Agent string into browser, engine, operating system and device type. Heuristic, fully client-side.

Render Markdown to HTML with a self-contained, sanitizing renderer — no raw HTML executes, all output is CSP-safe.

Assemble the <meta name="robots"> tag and X-Robots-Tag header from index/noindex/follow/noarchive and other directives.

Beautify JavaScript with Prettier, or compact it with a safe whitespace and comment minifier.

Beautify CSS with js-beautify, or compress it with csso (shorthand and hex shortening).

Beautify HTML with js-beautify, or minify it (whitespace and comments) while preserving pre, script and style.

Format SQL across many dialects (MySQL, PostgreSQL, T-SQL and more) with sql-formatter, or minify it.

Beautify or compress XML with fast-xml-parser. Normalises indentation, attributes and self-closing tags. Pure XML processing — no format conversion.

Validate, normalise or compress YAML with js-yaml. Tidies indentation and quote style, and splits multi-document (---) streams. Pure YAML processing — no format conversion.

Parse, align and preview CSV/TSV with custom delimiters and quotes, or convert between CSV and JSON. Sort and deduplicate columns — powered by papaparse.

Count characters, bytes, words, lines, sentences and paragraphs with multilingual-friendly word splitting.

Convert text between naming conventions, letter cases, East-Asian widths, and reverse it.

Generate placeholder text — paragraphs, sentences, words or lists — in Latin, English or Chinese, with an optional classic Lorem ipsum opening.

Count word and character n-gram frequencies in text — CJK via Intl.Segmenter, latin words via Unicode letters, or plain whitespace — with a Top-N table, share, and CSV export.

Convert any text — including Chinese, accents and emoji — into a clean URL-safe slug. Pick a separator, case, CJK-to-pinyin transliteration and an optional length cap, with live preview.

Generate a QR code from text or a URL and download it as PNG or SVG.

Read a QR code from an uploaded image and copy its decoded text.

Generate 1D barcodes (CODE128, EAN, UPC, CODE39 and more) as PNG or SVG.

Generate a structured QR code (WiFi, vCard, SMS, Geo, Event) from a form and download it as PNG or SVG.

Generate a Data Matrix 2D code (ECC200) — the compact symbol used for logistics and electronic-component marking. Choose shape, module size and margin, then export as PNG or SVG.

Convert an image to a Base64 data URL and back, with a live preview and download.

Inspect an image's dimensions, file size, media type, aspect ratio and megapixel count.

Resize and re-encode images with Canvas quality control, with a before/after size comparison.

Crop images in your browser — drag and resize the selection with mouse or touch, lock an aspect ratio, rotate or flip, then export to PNG, JPEG or WebP.

Add a text or logo watermark to images in your browser — position it on a 9-grid, custom spot, or tiled, set opacity and rotation, then export to PNG, JPEG or WebP. Nothing is uploaded.

Extract the dominant colors from an image right in your browser — median-cut quantization gives the Top-N colors plus the average, shown as HEX/RGB/HSL, ready to copy or download as a palette. Nothing is uploaded.

View an image's EXIF/metadata, and edit JPEG EXIF (set comment/copyright, strip GPS/all EXIF) — all in your browser, nothing uploaded.

Generate a complete favicon set from an image or a letter — produces favicon.ico (16/32/48), apple-touch-icon, Android Chrome icons and a webmanifest, packaged as a .zip. Nothing is uploaded.

Preview an SVG and strip editor junk — comments, <metadata>, Inkscape and Sodipodi namespaces, and inter-tag whitespace — directly in your browser. Live before/after byte count and viewBox info. Nothing is uploaded.

Build linear, radial and conic CSS gradients visually — drag color stops, preview live and copy the CSS or Tailwind v4 snippet.

Visually tune the container direction, justify, align, wrap and gap, plus per-child grow/shrink/basis/order/align-self — live preview and copy the CSS.

Stack multi-layer box-shadows (offset, blur, spread, color, inset) and tune a button's radius, border, padding and background — live preview and copy the CSS + HTML.

Quick reference for HTTP response status codes — 1xx through 5xx — with search.

Lookup table of common MIME types and their file extensions, with search.

Quick reference for the 128 standard ASCII (0–127) code points: decimal, hex, glyph, name and C-style escapes, with search.

AI accelerator throughput (FLOPS/TOPS), precision formats, and compute unit definitions.

Browse and search emoji by keyword across multiple languages, then copy in five formats — glyph, codepoint, HTML entity, JS escape, and CSS escape.

Lookup table of ISO 3166-1 country codes (alpha-2 / alpha-3 / UN M49 numeric), international calling codes, flags, capitals and ISO 4217 currencies — with search.

Interactive periodic table of all 118 chemical elements with category coloring, search, and a detail panel (atomic number, mass, electron configuration, discovery year, and common uses).

Compute the specificity (A, B, C) of any CSS selector — IDs, classes, attributes, pseudo-classes and elements — compare several selectors at once, and see how each piece contributes. Handles :is(), :not() and :where().

Compute a loan or mortgage with the equal-payment or equal-principal method: monthly payment, total interest, total repayment and an amortization schedule.

Safely evaluate an arithmetic expression with + − × ÷ % ^ and parentheses. No eval, no code execution.

Compute Body Mass Index from weight and height, with WHO category.

Estimate ovulation, fertile window and safe days from your cycle (Ogino/Knaus calendar method). For reference only — NOT a reliable contraceptive.

Convert between joules, calories, kilocalories, watt-hours, BTU and more.

Calculate the gap between two dates, or add/subtract days, weeks, months, years and workdays. All date math uses UTC, so results stay the same in every timezone.

Calculate your exact age in years, months and days from your birth date, plus the total days you have lived, the weekday you were born on, and the countdown to your next birthday. All date math uses UTC, so results stay the same in every timezone.

Boost focus with a Pomodoro timer: configurable focus and break sessions, a circular progress ring, a gentle chime and optional desktop notifications on each phase change, plus a daily completion tally saved on this device.