Free Developer Tools — 142 Online Utilities
142 tools · Online Utilities for Developers
A complete developer toolbox in your browser: format and validate JSON/YAML/XML, debug regex, decode JWTs, generate hashes and UUIDs, encode/decode base64 and URLs, lint code, and more. Most tools run entirely client-side so secrets and tokens never leave your machine.
JSON, YAML, XML · 14
🔧JSON FormatterFormat, validate and minify JSON🔧JSON Escape / UnescapeEscape plain text for JSON or decode escaped text🔧JSON Path FinderQuery JSON values using JSONPath-style paths🔧XML Sitemap GeneratorGenerate XML sitemap files from URL lists with optional metadata defaults.🔧JSON to TypeScriptGenerate TypeScript types and interfaces from JSON samples.🔧JSON to Zod SchemaGenerate Zod schema code from JSON input data.🔧JSON to Go StructConvert JSON into Go struct definitions with json tags.🔧JSON to Rust StructGenerate Rust structs from JSON with serde rename hints.🔧Schema Markup GeneratorGenerate JSON-LD for common schema types using guided forms.🔧Package JSON Scaffold GeneratorGenerate package.json scaffolds from project metadata and script presets.🔧JSON to CSharp ClassConvert JSON payload samples into C# class models with inferred nested types.🔧XML Sitemap ValidatorParse pasted sitemap XML for structural issues.✅JSON Schema ValidatorValidate JSON data against a JSON Schema Draft-07 and see detailed validation…🔧JSON Schema Generator from SampleAutomatically infer a JSON Schema from a sample JSON document to bootstrap sc…
Encoding & Decoding · 7
🔧Base64Encode and decode Base64 strings🔧JWT DecoderDecode and inspect JWT tokens🔧URL EncoderEncode and decode URLs🔧HTML Decode and EncodeEncode and decode HTML entities in Named / Basic and Numeric modes.🔧JavaScript String EscapeEncode and decode JavaScript escape sequences for safe string handling.📜Certificate DecoderDecode RSA X.509 certificates from PEM or base64 DER to see subject, issuer, …🔤ASCII TableAll 128 ASCII codes in decimal, hex, octal and binary, with each character, H…
Hashing & Crypto · 10
🔧Hash GeneratorGenerate SHA-256, SHA-1, MD5 hashes🔧Paste and ShareShare text with a short link, expiry, optional max opens, password, and QR code🔧Markdown & HTML ShareUpload a .md or .html file, get a short link; recipients view it rendered, co…🔧Box Shadow GeneratorTune blur, spread, offsets, color, and inset shadows with an instant CSS prev…🔧Text Shadow GeneratorStack up to three readable text shadows and export CSS for headings and hero …🔧AES Text EncryptorPBKDF2-hardened AES-GCM encrypt and decrypt.🔧RSA Key GeneratorIssue RSA-OAEP 2048 PEM pairs via Web Crypto.🔐bcrypt Generator & VerifierHash passwords with bcrypt (cost 8–14) and verify hashes in-browser.🔏PGP Encrypt / DecryptEncrypt, decrypt, generate PGP key pairs, and sign/verify messages in-browser…🔧File Hash Multi (MD5, SHA-1, SHA-256, SHA-512)Compute MD5, SHA-1, SHA-256, and SHA-512 of any file in your browser
Regex & Pattern · 4
🔧Regex TesterTest regular expressions with live matches🔧Cron Expression GeneratorBuild 5-field cron expressions quickly🕐Cron Expression DescriberTranslate a numeric cron expression into a field-by-field description and pre…🔎Regex Generator from SamplesGenerate a regular expression from positive and negative example strings — ru…
Network, DNS & HTTP · 22
🔧JavaScript MinifierMinify JavaScript by removing comments, trimming whitespace, and outputting c…🔧JavaScript BeautifierBeautify JavaScript snippets with block indentation and line breaks after sta…🔧HTTP Status LookupSearch HTTP status codes and names with class-based filters and notes.🔧Htaccess Snippet GeneratorGenerate common Apache .htaccess snippet blocks and merge selections.🔧Nginx Snippet GeneratorGenerate and merge common Nginx config snippets for deployment baselines.🔧DNS Lookup ToolQuery public DNS records with SSRF-safe hostname validation🔧HTTP Headers CheckerInspect response status and headers from public HTTPS origins🔧SSL Certificate CheckerPeek TLS certificate metadata with SSRF-safe hostname rules🔧Clip Path GeneratorExplore polygon, circle, ellipse, and inset clip-path presets with live previ…🔧Subnet CalculatorIPv4 network broadcast host ranges from CIDR.🔧IPv4 to IPv6 ConverterIPv4-mapped IPv6 form (::ffff: plus the dotted IPv4 address).🌐WHOIS Domain LookupLook up a domain's registrar, dates, status and name servers through the Util…📍IP Geolocation LookupLook up the country, region, city, ISP and coordinates of an IPv4 or IPv6 add…🌍DNS Propagation CheckerCompare a DNS record across the Cloudflare, Google and Quad9 public resolvers…🔄Reverse DNS LookupLook up the PTR (reverse DNS) hostname for an IP address through the UtilityK…📡Online Ping TestTime five HTTP requests to a URL made through the UtilityKit server and see a…⚡JavaScript Online RunnerRun JavaScript in a sandboxed iframe — instant execution with console output …🔷TypeScript PlaygroundTranspile TypeScript to JavaScript in your browser with configurable target a…📡HTTP Request BuilderSend HTTP requests from your browser via a server-side proxy — set method, he…🔐DNSSEC CheckerLook up DS, DNSKEY, and RRSIG records for a domain to confirm DNSSEC is enabl…🚫IP Blacklist CheckCheck an IPv4 address against Spamhaus ZEN, SpamCop and Barracuda DNS blockli…🔌Open Port CheckerRun a single TCP connect-test from our backend to see whether one port on a p…
Code & Markup · 17
🔧CSS MinifierMinify CSS by removing comments and whitespace🔧HTML FormatterBeautify and indent raw HTML code🔧HTML MinifierMinify HTML by removing comments and unnecessary whitespace while preserving …🔧CSS BeautifierBeautify CSS with clean indentation and optional comment preservation.🔧SemVer Tester DiffValidate and compare semantic versions, including bump classification.🔧CSS Gradient GeneratorCreate linear or radial gradients with stops, angles, and copy-ready backgrou…🔧CSS Triangle GeneratorCreate directional CSS triangles using the transparent border technique with …🔧CSS Spinner GeneratorBrowse spinner presets, tweak size speed and color, and copy animation-ready …🔧CSS Button GeneratorStyle padding, radius, colors, borders, and optional hover darken with instan…🔧CSS Grid GeneratorBuild a CSS grid visually: set columns, rows and gaps, drag across cells to p…🔧CSS Keyframes GeneratorCompose starter animations with timing controls and copy @keyframes blocks.🔧CSS Transform PlaygroundCombine translate, rotate, scale, and skew values with a live preview box and…🔧CSS Filter PlaygroundStack blur, color, and tonal CSS filters with sliders and copy-ready filter d…📐PX to REM ConverterConvert between CSS units — px, rem, em, %, pt, pc, cm, mm, in, vw and vh — w…⚖️CSS Specificity CalculatorCalculate the specificity of a CSS selector and compare it with a second sele…📦CSS Box Model VisualizerVisualize the CSS box model interactively — adjust margin, border, padding, a…🦆SQL Online RunnerQuery CSV and JSON files with SQL in your browser — powered by DuckDB-WASM.
IDs, UUIDs & Tokens · 4
More tools · 64
🔧Color ConverterConvert between HEX, RGB, HSL🔧Unix Time ConverterConvert Unix timestamps to readable date and back🔧cURL to FetchConvert common cURL commands to fetch()🔧Meta Tag GeneratorGenerate essential HTML head tags for SEO and metadata in one place.🔧Robots.txt GeneratorGenerate a valid robots.txt with user-agent, allow/disallow, sitemap, and hos…🔧Glob TesterTest glob patterns against newline file/path candidates.🔧MIME Type LookupFind MIME types from extensions and reverse-map MIME to extensions.🔧User Agent ParserParse user-agent strings into browser, engine, OS, and device details.🔧URL ParserParse URLs into protocol, host, path, query parameters, and hash parts.🔧Data URL BuilderBuild and decode text data URLs with MIME type, charset, and Base64 options.🔧OG Tag GeneratorGenerate Open Graph meta tags with preview-friendly fields and copy-ready out…🔧Twitter Card GeneratorGenerate Twitter/X card tags and preview social metadata quickly.🔧Canonical Tag GeneratorNormalize URLs and generate canonical link tags for SEO-safe page metadata.🔧Gitignore GeneratorGenerate merged and deduplicated .gitignore output from stack presets.🔧Editorconfig GeneratorGenerate .editorconfig with global defaults and per-extension overrides.🔧License GeneratorGenerate common OSS license templates with year and copyright holder.🔧README GeneratorGenerate markdown README scaffolds from core project fields.🔧Dockerfile GeneratorGenerate Dockerfile templates for Node, Python, and static Nginx apps.🔧GitHub Actions Workflow GeneratorGenerate starter CI/deploy workflow YAML for common project types.🔧RSS Atom GeneratorGenerate RSS 2.0 and Atom XML feeds from metadata and entry rows.🔧Border Radius GeneratorShape corners with unified or per-corner sliders and export shorthand border-…🔧Glassmorphism GeneratorTune blur, saturation, translucency, and borders for frosted glass panels.🔧Neumorphism GeneratorCraft soft extruded or inset soft UI shadows tuned for light and dark surfaces.🔧Flexbox PlaygroundTune flex-direction, alignment, gap, and item counts while copying container …🔧Aspect Ratio CalculatorFind the aspect ratio of any width and height, solve a missing width or heigh…🔧Container Query HelperAuthor @container boilerplate with names and breakpoints for component-driven…🔧Scrollbar StylerTint scrollbar thumbs and tracks for WebKit and Firefox using copy-ready pseu…🔧SERP Preview ToolDesktop and mobile style snippets with soft character guides.🔧Hreflang Tag GeneratorBuild alternate link rows for multilingual SEO.🔧Keyword Density CheckerToken frequencies with optional stopword trimming.🔧Password Strength CheckerHeuristic scoring without uploading secrets.🔧Email Header AnalyzerSummarize Received chains and auth hints from pasted headers.🆔CUID GeneratorGenerate CUID-style IDs — a 'c' prefix, base36 timestamp and counter, and ran…❄️Snowflake ID GeneratorGenerate Twitter-style Snowflake IDs — 64-bit time-ordered unique integers us…🍃MongoDB ObjectId GeneratorGenerate MongoDB-format ObjectIds and decode existing ones to read their embe…🔏SSH Public Key FingerprintCalculate the SHA-256 fingerprint of an SSH public key in Base64 and hex to v…🔐htpasswd GeneratorGenerate SHA-1 ({SHA}) htpasswd entries in the browser, or get the htpasswd c…🔒Password Entropy CalculatorCalculate the entropy of a password in bits and estimate full brute-force tim…♿WCAG Contrast CheckerCheck foreground and background color contrast ratios against WCAG 2.1 AA and…👁Color Blindness SimulatorSimulate how an image appears with protanopia, deuteranopia or tritanopia, si…🌊Tailwind Class to CSS ConverterLook up the CSS declarations behind about 250 common Tailwind CSS utility cla…📈Cubic Bezier EditorVisually edit and preview CSS cubic-bezier easing curves with interactive con…🔤Font Pairing ToolPreview a heading and body pairing from 20 Google Fonts on sample text, with …📱Responsive Breakpoint PreviewerPreview a public URL in scaled iframes at 375, 768, 1024 and 1440 px viewport…📧MX Record LookupLook up a domain's MX records, sorted by priority, and see which known email …🔍Website Status CheckerCheck whether any website or URL is up or down and see its HTTP response code…🤖Robots.txt TesterFetch a site's robots.txt through the UtilityKit server and test whether a pa…🧜Mermaid Live EditorWrite Mermaid diagram syntax and see a live SVG preview — flowcharts, sequenc…🕸️Graphviz OnlineRender Graphviz DOT language graphs in-browser with WASM — supports dot, neat…🐍Python Online CompilerRun Python 3 code in your browser via Pyodide — no install, no server.📐PlantUML RendererWrite PlantUML diagrams and preview them as SVG — sequence, class, activity, …📸Page Screenshot ServiceCapture full-page or viewport screenshots of any public URL as PNG or JPG usi…🔦Lighthouse TestFetch a Google PageSpeed Insights (Lighthouse) performance score and the top …🔗Broken Link CheckerFind broken and dead links on any webpage. Live status updates and CSV export…🔧Hex & Binary ViewerInspect any file as a hex + ASCII dump in your browser📧SPF Record CheckerLook up and parse a domain's SPF DNS record. Counts the record's own lookup m…🛡️DMARC Record CheckerLook up the DMARC TXT record at _dmarc.<domain>, parse every tag (p, sp, pct,…🔑DKIM Record CheckerFetch a DKIM TXT record at <selector>._domainkey.<domain>, parse the public k…🛠️DMARC Record GeneratorBuild a valid DMARC TXT record with policy, percentage, alignment modes, and …🛠️SPF Record GeneratorCompose an SPF TXT record from email-provider presets, custom includes, and I…📨SMTP Test ToolConnect to any SMTP host on port 25 (or a custom port), capture the banner, s…🌐Subdomain FinderDiscover subdomains for any domain via passive enumeration of Certificate Tra…🧮LLM VRAM CalculatorEstimate the GPU VRAM or unified memory a local LLM needs at each quantizatio…🖥️What GPU Do I Have?See which graphics card your browser uses, whether it is integrated or dedica…
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