# ProgrammerKit > Free online developer tools — JSON, YAML, XML, CSV, SQL, HTML, CSS formatters, Base64, JWT, hash, regex, QR, UUID, color and 30+ more. Fast, private, in-browser. ProgrammerKit is a free collection of in-browser developer utilities. Every tool runs entirely client-side using standard Web APIs — no input data is ever transmitted, logged, or stored on a server. The site requires no sign-up and is supported by non-intrusive advertising. ## Key pages - [Home](https://programmerkit.com/): Browse and search every tool by category. - [About](https://programmerkit.com/about): Mission, principles, and audience. - [Privacy Policy](https://programmerkit.com/privacy): How data is (not) collected. - [Terms of Use](https://programmerkit.com/terms): Acceptable-use and disclaimers. - [Contact](https://programmerkit.com/contact): How to reach the team. ## Formatters - [Compare Anything Engine](https://programmerkit.com/tools/compare-anything): Side-by-side diff for JSON, XML, contracts, specs, job offers — with decision matrix. - [JSON Formatter & Validator](https://programmerkit.com/tools/json-formatter): Format, beautify, minify and validate JSON instantly in your browser. - [XML Formatter & Minifier](https://programmerkit.com/tools/xml-formatter): Pretty-print, minify and validate XML documents online. - [YAML Formatter & Validator](https://programmerkit.com/tools/yaml-formatter): Validate and re-emit YAML in a clean normalized form. - [SQL Formatter](https://programmerkit.com/tools/sql-formatter): Format SQL queries with proper indentation and keyword casing. - [HTML Formatter & Minifier](https://programmerkit.com/tools/html-formatter): Pretty-print or minify HTML markup. - [CSS Formatter & Minifier](https://programmerkit.com/tools/css-formatter): Beautify or minify CSS stylesheets. - [JavaScript Minifier](https://programmerkit.com/tools/js-minifier): Strip comments and whitespace from JavaScript safely. - [JSON Diff Checker](https://programmerkit.com/tools/json-diff): Compare two JSON objects and see added, removed and changed keys. - [JSON Key Sorter](https://programmerkit.com/tools/json-sort): Sort object keys alphabetically at every depth. - [JSON Path Tester](https://programmerkit.com/tools/json-path): Query JSON with dot/bracket paths and JSONPath expressions. - [SVG Minifier](https://programmerkit.com/tools/svg-minifier): Minify SVG markup by stripping comments, metadata and whitespace. - [CSV Diff Checker](https://programmerkit.com/tools/csv-diff): Compare two CSV files row-by-row to find changes. ## Converters - [YAML ↔ JSON Converter](https://programmerkit.com/tools/yaml-json): Convert YAML to JSON and JSON to YAML. - [CSV ↔ JSON Converter](https://programmerkit.com/tools/csv-json): Convert CSV spreadsheets to JSON arrays and back. - [JSON ↔ XML Converter](https://programmerkit.com/tools/json-xml): Convert between JSON and XML with one click. - [JSON to TypeScript Interface](https://programmerkit.com/tools/json-to-ts): Generate TypeScript interfaces from any JSON sample. - [Unix Timestamp Converter](https://programmerkit.com/tools/timestamp-converter): Convert between Unix timestamps and human dates. - [Number Base Converter](https://programmerkit.com/tools/number-base): Convert numbers between binary, octal, decimal and hex. - [CIDR / Subnet Calculator](https://programmerkit.com/tools/cidr-calculator): Calculate network range, mask, hosts and broadcast for any CIDR. - [CSV to Markdown Table](https://programmerkit.com/tools/csv-to-markdown): Convert CSV data to GitHub-flavored Markdown tables. - [SVG to CSS Background](https://programmerkit.com/tools/svg-to-css): Convert SVG to a data-URI usable as a CSS background. - [curl to fetch / Code Converter](https://programmerkit.com/tools/curl-to-fetch): Convert curl commands into JavaScript fetch() calls. - [HTML to JSX Converter](https://programmerkit.com/tools/html-to-jsx): Convert HTML markup into valid React JSX. - [JSON Schema Generator](https://programmerkit.com/tools/json-schema-gen): Generate a JSON Schema (draft-07) from any JSON sample. - [Batch Timestamp Converter](https://programmerkit.com/tools/timestamp-batch): Convert a list of Unix timestamps to dates (or vice versa). - [Image Resizer](https://programmerkit.com/tools/image-resize): Resize PNG, JPG, WebP images in your browser — keep or break aspect ratio. - [Image Compressor (JPEG / WebP)](https://programmerkit.com/tools/image-compress): Compress JPEG and WebP images by adjusting quality. - [Image Format Converter](https://programmerkit.com/tools/image-convert): Convert between PNG, JPEG and WebP image formats. ## Encoders - [Base64 Encoder / Decoder (with File Support)](https://programmerkit.com/tools/base64): Encode or decode Base64 text and convert files to/from Base64. - [URL Encoder / Decoder](https://programmerkit.com/tools/url-encoder): Percent-encode or decode URLs and query strings safely. - [HTML Entity Encoder / Decoder](https://programmerkit.com/tools/html-entities): Escape HTML special characters or decode named/numeric entities. - [String Escape / Unescape](https://programmerkit.com/tools/string-escape): Escape strings for JSON, JavaScript, SQL and shell. - [Base32 Encoder / Decoder](https://programmerkit.com/tools/base32): Encode and decode Base32 strings (RFC 4648). - [Image to Base64 / Data URI](https://programmerkit.com/tools/image-to-base64): Convert any image (PNG, JPG, SVG, WebP, GIF) to a base64 data URI. - [Base64 / Data URI to Image](https://programmerkit.com/tools/base64-to-image): Decode a base64 string or data URI back into a downloadable image. ## Generators - [UUID Generator (v4)](https://programmerkit.com/tools/uuid-generator): Generate cryptographically random UUIDs (v4). - [Password Generator](https://programmerkit.com/tools/password-generator): Generate strong random passwords with customizable rules. - [Lorem Ipsum Generator](https://programmerkit.com/tools/lorem-ipsum): Generate placeholder text in paragraphs, sentences or words. - [QR Code Generator](https://programmerkit.com/tools/qr-generator): Generate downloadable QR codes for any URL or text. - [URL Slug Generator](https://programmerkit.com/tools/slug-generator): Convert any text into a clean URL-safe slug. - [.gitignore Generator](https://programmerkit.com/tools/gitignore-generator): Combine .gitignore templates for popular languages and IDEs. - [Placeholder Image URL Builder](https://programmerkit.com/tools/placeholder-image): Generate placeholder image URLs for mockups and prototypes. - [Passphrase Generator (Diceware)](https://programmerkit.com/tools/passphrase-generator): Generate strong memorable passphrases from a random word list. - [vCard (.vcf) Generator](https://programmerkit.com/tools/vcard-generator): Build a vCard 3.0 contact card and download as .vcf. - [Open Graph Meta Generator](https://programmerkit.com/tools/og-meta-generator): Generate Open Graph and Twitter Card meta tags with live preview. - [robots.txt Builder](https://programmerkit.com/tools/robots-txt-builder): Build a robots.txt file with rules for search engine crawlers. - [Visual Cron Expression Builder](https://programmerkit.com/tools/cron-builder): Build cron expressions visually and see the next run times. ## Text - [Markdown Preview](https://programmerkit.com/tools/markdown-preview): Live preview of GitHub-flavored Markdown. - [Markdown to HTML](https://programmerkit.com/tools/markdown-to-html): Convert Markdown to clean HTML you can copy. - [Text Diff Checker](https://programmerkit.com/tools/text-diff): Compare two blocks of text line-by-line. - [Text Case Converter](https://programmerkit.com/tools/case-converter): Transform text between camelCase, snake_case, kebab-case and more. - [Word & Character Counter](https://programmerkit.com/tools/word-counter): Count words, characters, sentences and reading time. - [Regex Tester](https://programmerkit.com/tools/regex-tester): Test JavaScript regular expressions with live highlighting. - [Markdown Table Generator](https://programmerkit.com/tools/markdown-table): Build Markdown tables visually — add rows and columns, then copy. - [Sort Lines](https://programmerkit.com/tools/sort-lines): Sort lines alphabetically, numerically, by length, ascending or descending. - [Remove Duplicate Lines](https://programmerkit.com/tools/dedupe-lines): Remove duplicate lines from any text block. - [Reverse Text & Lines](https://programmerkit.com/tools/reverse-text): Reverse a string character-by-character or reverse line order. - [Find & Replace (with Regex)](https://programmerkit.com/tools/find-replace): Find and replace text with optional regex, case and word options. - [Whitespace Cleaner](https://programmerkit.com/tools/whitespace-cleaner): Trim, normalize or strip whitespace from text. - [Text Repeater](https://programmerkit.com/tools/text-repeater): Repeat any string a chosen number of times with separators. - [Unicode Character Inspector](https://programmerkit.com/tools/unicode-inspector): Inspect every character: codepoint, name, hex, UTF-8 bytes. - [ASCII Table Reference](https://programmerkit.com/tools/ascii-table): Searchable ASCII table with hex, decimal, octal and HTML codes. - [Markdown TOC Generator](https://programmerkit.com/tools/markdown-toc): Generate a Table of Contents from Markdown headings. - [Bulk Email Validator](https://programmerkit.com/tools/email-validator): Validate email syntax for many addresses at once. - [String Similarity Checker](https://programmerkit.com/tools/string-similarity): Compare two strings: Levenshtein distance, similarity %. - [Readability Score (Flesch)](https://programmerkit.com/tools/readability-score): Compute Flesch Reading Ease and grade-level scores for any text. - [Keyword Density Checker](https://programmerkit.com/tools/keyword-density): Count word frequency and density for SEO content analysis. ## CSS - [CSS Gradient Generator](https://programmerkit.com/tools/gradient-generator): Build linear and radial CSS gradients visually. - [CSS Box Shadow Generator](https://programmerkit.com/tools/box-shadow): Visually craft CSS box-shadow rules with live preview. - [CSS Border Radius Generator](https://programmerkit.com/tools/border-radius): Generate CSS border-radius shapes with corner control. - [Flexbox Playground](https://programmerkit.com/tools/flexbox-playground): Visually test flex container and item properties. - [CSS Grid Generator](https://programmerkit.com/tools/css-grid): Generate CSS grid-template-columns/rows visually. - [CSS Unit Converter (px/em/rem/%)](https://programmerkit.com/tools/css-units): Convert between px, em, rem and percent based on root size. - [Color Palette Generator](https://programmerkit.com/tools/color-palette): Generate complementary, analogous and triadic palettes from any color. - [WCAG Color Contrast Checker](https://programmerkit.com/tools/wcag-contrast): Check WCAG AA / AAA contrast ratios between two colors. - [CSS clamp() Fluid Size Generator](https://programmerkit.com/tools/css-clamp): Generate fluid responsive clamp() values for typography and spacing. - [CSS Box Model Visualizer](https://programmerkit.com/tools/box-model): Interactively visualize margin, border, padding and content. ## Math - [Random Number Generator](https://programmerkit.com/tools/random-number): Generate random integers or decimals in any range. - [Dice Roller (RPG Notation)](https://programmerkit.com/tools/dice-roller): Roll dice using standard RPG notation like 2d6+3 or 1d20. - [Roman Numeral Converter](https://programmerkit.com/tools/roman-numerals): Convert between Roman numerals and Arabic numbers. - [Percentage Calculator](https://programmerkit.com/tools/percentage-calc): Calculate percentages, increases, decreases and ratios. - [Unit Converter](https://programmerkit.com/tools/unit-converter): Convert length, weight, temperature, volume and more. - [Loan / EMI Calculator](https://programmerkit.com/tools/emi-calculator): Compute monthly payments, total interest and amortization. - [BMI Calculator](https://programmerkit.com/tools/bmi-calculator): Compute Body Mass Index in metric or imperial units. - [Luhn / Credit Card Validator](https://programmerkit.com/tools/luhn-checker): Validate credit card numbers using the Luhn checksum. - [Aspect Ratio Calculator](https://programmerkit.com/tools/aspect-ratio): Calculate width or height keeping the aspect ratio. ## Date - [Age Calculator](https://programmerkit.com/tools/age-calculator): Calculate exact age in years, months, days and total seconds. - [Date Difference Calculator](https://programmerkit.com/tools/date-diff): Calculate the difference between two dates. - [Time Zone Converter](https://programmerkit.com/tools/timezone-converter): Convert times across world time zones. - [Pomodoro Focus Timer](https://programmerkit.com/tools/pomodoro-timer): Classic 25/5 Pomodoro technique with sound and notification. - [Stopwatch with Laps](https://programmerkit.com/tools/stopwatch): Millisecond-precision stopwatch with lap times. - [Countdown Timer](https://programmerkit.com/tools/countdown-timer): Set a countdown to any duration or target date with sound alert. ## Web - [HTTP Status Code Lookup](https://programmerkit.com/tools/http-status): Search 1xx–5xx HTTP status codes with descriptions. - [User-Agent Parser](https://programmerkit.com/tools/user-agent): Parse browser, OS and device from any User-Agent string. - [Cron Expression Explainer](https://programmerkit.com/tools/cron-explainer): Translate cron expressions into plain English. - [Color Converter — HEX, RGB, HSL](https://programmerkit.com/tools/color-converter): Convert between HEX, RGB and HSL formats with live preview. - [Semver Comparator](https://programmerkit.com/tools/semver-compare): Compare semantic versions and check ranges. - [MIME Type Lookup](https://programmerkit.com/tools/mime-lookup): Search MIME types by file extension or vice versa. - [UUID Validator & Inspector](https://programmerkit.com/tools/uuid-inspector): Validate UUIDs and decode v1/v7 timestamps. - [URL Parser](https://programmerkit.com/tools/url-parser): Parse a URL into protocol, host, path, query and hash. - [IPv4 ↔ IPv6 Converter](https://programmerkit.com/tools/ipv4-ipv6): Convert IPv4 addresses to IPv6-mapped form and back. - [Webcam Snapshot](https://programmerkit.com/tools/webcam-snapshot): Capture a still photo from your webcam and download it as PNG. - [Text to Speech](https://programmerkit.com/tools/text-to-speech): Read any text aloud using built-in browser voices. - [Browser Notepad (auto-save)](https://programmerkit.com/tools/notepad): Distraction-free notepad with localStorage auto-save and word count. ## Cipher - [ROT13 Cipher](https://programmerkit.com/tools/rot13): Encode and decode ROT13 — a simple letter substitution cipher. - [Caesar Cipher](https://programmerkit.com/tools/caesar-cipher): Encrypt or decrypt text with a configurable Caesar shift. - [Morse Code Translator](https://programmerkit.com/tools/morse-code): Translate text to Morse code and back. - [Binary ↔ Text Converter](https://programmerkit.com/tools/binary-text): Convert plain text to binary representation and back. ## Crypto - [JWT Decoder](https://programmerkit.com/tools/jwt-decoder): Decode and inspect JSON Web Tokens — header, payload and signature. - [Hash Generator (SHA-1/256/384/512)](https://programmerkit.com/tools/hash-generator): Generate cryptographic hashes using the Web Crypto API. - [HMAC Generator (SHA-256/384/512)](https://programmerkit.com/tools/hmac-generator): Generate keyed-hash message authentication codes (HMAC). - [JWT Signer / Builder (HS256)](https://programmerkit.com/tools/jwt-builder): Sign JSON Web Tokens locally with HS256, HS384 or HS512. - [Password Strength Meter](https://programmerkit.com/tools/password-strength): Estimate password entropy and crack time live. - [.htpasswd Generator](https://programmerkit.com/tools/htpasswd): Generate Apache .htpasswd lines (SHA-1) in your browser. - [File Hash Calculator](https://programmerkit.com/tools/file-hash): Compute SHA-1, SHA-256, SHA-384 and SHA-512 of any file, locally. - [Text Encryption (AES-GCM)](https://programmerkit.com/tools/text-encrypt): Encrypt and decrypt text with a password using AES-GCM.