Developer tools that stay in your browser

76 tools

• JSON FormatterFormat, validate, minify and sort JSON — errors point to line and columnFormatters and converters
• Base64Encode and decode Base64 / Base64URL with correct UTF-8 handlingEncoders and utilities
• SHA Hash & HMACSHA-1/256/384/512 digests and HMAC with Web Crypto, for text or filesSecurity tools
• UUID GeneratorGenerate UUID v4 and time-ordered v7, in bulkEncoders and utilities
• JWT DecoderDecode JWT header and payload with readable exp/iat — signature is NOT verifiedSecurity tools
• URL ParserBreak a URL into parts, edit query params, and spot look-alike (IDN) hostnamesNetwork and API tools
• CSV ⇄ JSONConvert CSV to JSON and back — delimiter detection, header row, quoted fieldsFormatters and converters
• Timestamp ConverterConvert epoch seconds/ms to dates across timezones, and compute durationsEncoders and utilities
• Text DiffCompare two texts by line, word or character — side by side, inline or as a unified patchFormatters and converters
• JSON DiffCompare two JSON documents structurally — added, removed and changed pathsFormatters and converters
• Color ConverterConvert colors between HEX, RGB, HSL and OKLCH with alphaFrontend and CSS tools
• CSS Unit ConverterConvert between px, rem, em, %, vw, vh, pt and physical unitsFrontend and CSS tools
• Contrast CheckerWCAG contrast ratio and AA/AAA pass/fail for text and UI colorsFrontend and CSS tools
• Markdown PreviewRender Markdown safely — raw HTML escaped, output sanitized, remote images blocked by defaultFormatters and converters
• Regex TesterLive regex matches with groups, flags and replace, run in a worker that stops after 3 secondsEncoders and utilities
• JSON Tree ViewerBrowse JSON as a collapsible tree and copy the path or value of any nodeFormatters and converters
• YAML FormatterValidate and format YAML, convert YAML ⇄ JSONFormatters and converters
• XML FormatterValidate, pretty-print and minify XMLFormatters and converters
• TOML FormatterValidate and normalize TOML, convert TOML ⇄ JSONFormatters and converters
• SQL FormatterFormat SQL queries for common dialectsFormatters and converters
• HTML FormatterPretty-print HTML and Vue templates, including inline script and styleFormatters and converters
• CSS FormatterPretty-print CSS, SCSS and LessFormatters and converters
• GraphQL FormatterPretty-print GraphQL queries, mutations and schemasFormatters and converters
• JavaScript FormatterPretty-print JavaScript, JSX, TypeScript and TSX with PrettierFormatters and converters
• JSON Schema Validator & MockValidate JSON against a JSON Schema (draft 2020-12) and generate seeded test data from it (Mock Data Studio: JSON, CSV, TS fixtures)Formatters and converters
• Environment Config DiffCompare two configs (.env, JSON, YAML, TOML, INI) key by key — missing, extra and changed keys, secrets maskedFormatters and converters
• JSON / GraphQL → TypesGenerate TypeScript interfaces, Zod schemas, JSON Schema (2020-12) or Go structs from sample JSON — or TypeScript from a GraphQL schema and operationFormatters and converters
• OpenAPI WorkbenchBrowse an OpenAPI 3 spec by tag and endpoint, check its $refs, send an endpoint to the API Client or copy it as cURL / fetch / Axios, diff two versions for breaking changes, and diff two GraphQL schemas (SDL or introspection)Network and API tools
• Webhook InspectorPaste webhook payloads to see their structure and an inferred schema, validate them against a JSON Schema, compare two payload versions (shape and fields), and generate example payloads — nothing is sentNetwork and API tools
• Database Schema ToolkitRead SQL DDL (PostgreSQL, MySQL, SQLite) into tables, keys and indexes, draw an ERD (SVG / Mermaid), diff two versions, and generate TypeScript types and mock rows — never connects to a databaseStorage and database tools
• Color PaletteGenerate a 50–950 shade scale and color harmonies from one color; export CSS variables or TailwindFrontend and CSS tools
• CSS GradientBuild or parse linear, radial and conic gradients with live previewFrontend and CSS tools
• Border RadiusPer-corner and elliptical border-radius builder with shortest shorthandFrontend and CSS tools
• Box ShadowLayered box-shadow generator and parser with live previewFrontend and CSS tools
• Robots.txt TesterPaste a robots.txt, pick a crawler and test URLs: allowed or blocked, by which rule and why, with warningsSEO toolsWeb + extension (hybrid)
• XML Sitemap ExplorerPaste or load a sitemap and list every URL with lastmod, changefreq and priority, flagging duplicates, malformed and other-origin URLs and invalid datesSEO toolsWeb + extension (hybrid)
• Content GapPaste your page and competitor pages to see terms and headings they share that yours lacks, grouped by topicSEO toolsWeb + extension (hybrid)
• Indexability InspectorEnter a URL's status, headers, meta robots, canonical and robots.txt to see whether it is likely indexable, not, or conflictingSEO toolsWeb + extension (hybrid)
• Snapshot CompareCompare two page snapshots exported from the DevKit Forge extension by module, with regressions flaggedSEO toolsWeb + extension (hybrid)
• Structured DataPaste JSON-LD to see its entities and check it: syntax, schema.org value types, and the fields Google documents for rich results (with the rule source and date)SEO toolsWeb + extension (hybrid)
• SERP PreviewPreview how a title, description and URL you type may look in search results on desktop and mobile, cut by pixel widthSEO toolsWeb + extension (hybrid)
• Social PreviewPreview how a title, description and image URL you type may look when shared on Facebook, X and LinkedIn, and copy the Open Graph and Twitter tagsSEO toolsWeb + extension (hybrid)
• Keyword DensityCount the words and 2- and 3-word phrases in text you paste, with stop words filtered for English and Vietnamese, plus word count, reading time and readabilitySEO toolsWeb + extension (hybrid)
• Stack Trace AnalyzerPaste a stack trace from Chrome, Firefox, Safari or Node.js: frames, your code vs libraries, recursion folded, likely originDebugging tools
• Security HeadersPaste a response's headers to score its security headers (CSP, HSTS, CORS, cookies, framing) and get the fix for each issueSecurity tools
• Build InspectorUpload or paste a Vite manifest, webpack stats, Next.js build manifest or file list to see sizes, source maps and unhashed files, and compare two buildsFrontend and CSS tools
• Real User MetricsPaste or upload web-vitals samples or a CrUX export to see p75 with enough samples and a split by device, browser, region, viewport and routeFrontend and CSS tools
• Byte Size ConverterConvert and format byte sizes in SI (kB) and IEC (KiB) unitsEncoders and utilities
• Number Base ConverterConvert between decimal, hex, binary and octal with arbitrary precisionEncoders and utilities
• Hex / Binary ↔ TextConvert text to UTF-8 bytes in hex or binary, and backEncoders and utilities
• HTML EntitiesEscape and unescape HTML entities (named, decimal, hex)Encoders and utilities
• URL Encode/DecodePercent-encode or decode URL components and full URLsEncoders and utilities
• Unicode Escape & InspectorEscape/unescape JS (\u, \u{…}), CSS and HTML forms; inspect code points, UTF-8 and UTF-16Encoders and utilities
• Lorem IpsumGenerate placeholder words, sentences or paragraphsEncoders and utilities
• Cron ExplainerExplain a cron expression in plain English and list the next run timesEncoders and utilities
• Text TransformChange case, trim, dedupe, sort, prefix/suffix, slugify, count, and JSON-escape textEncoders and utilities
• Random GeneratorCrypto-secure random strings, Nano IDs, ULIDs and integersEncoders and utilities
• QR CodeGenerate QR codes for text, a URL, Wi-Fi, email or a phone number, drawn as SVG in your browserEncoders and utilities
• JSONPath QueryQuery JSON with JSONPath — wildcards, recursive descent, slices and safe filtersFormatters and converters
• SVG OptimizerClean and shrink an SVG (editor data, comments, long numbers, empty groups), remove unsafe parts, and export as file, data URI, CSS or ReactFormatters and converters
• .env / INI / Properties → JSONParse .env, INI and Java .properties files into JSON — flags and masks secret valuesFormatters and converters
• Secret ScannerFind leaked credentials in text or a file — API keys, tokens, passwords, private keys — and copy a redacted copySecurity tools
• PEM / Certificate InspectorIdentify PEM blocks and inspect X.509 certificates (subject, issuer, validity, SAN, key) and ASN.1 — no verificationSecurity tools
• Protobuf InspectorDecode protobuf bytes from hex, Base64 or a file into fields and wire types, in your browserFormatters and converters
• CSS → TailwindSuggest Tailwind utility classes for CSS declarations, in your browserFrontend and CSS tools
• CORS DebuggerPaste request and response headers or a HAR file and see why the browser blocks a cross-origin requestSecurity tools
• i18n CheckerCompare locale JSON files: missing, extra and empty keys, untranslated text, placeholders that don't match, strings that may overflowTesting tools
• API Failure ScenariosFrom an OpenAPI spec or one request, build failure scenarios for your tests — HTTP errors (with documented error bodies), timeouts and network failures, malformed and schema-violating responses — exported as Playwright route mocks or JSONTesting tools
• Git HelpersBranch names from ticket titles, Conventional Commit builder and checks, and changelogs from your commitsEncoders and utilities
• HTML → Text & LinksExtract plain text, links, images and headings from pasted HTML without running itEncoders and utilities
• Code SnippetsCopy-ready HTML, CSS and JS boilerplate: reset, meta tags, debounce, and moreEncoders and utilities
• Log ViewerRead JSON, logfmt, Apache/Nginx and plain logs as a table: filter by level or text, follow one request, secrets maskedDebugging tools
• Source Map ExplorerCheck a source map, look up minified positions in your original code and back, and see what a public map exposesDebugging tools
• Big JSON / CSV ViewerOpen large JSON or CSV files without freezing the page: parsed in a worker, browsed as a tree or a tableFormatters and converters
• Palette from ImagePick an image to get its 5–12 dominant colors with shares, names and text contrast; copy them as CSS or TailwindFrontend and CSS tools
• Email PreviewPreview HTML, Markdown or .eml email at phone, email and desktop widths; flag what Gmail and Outlook don't support; plain-text versionFormatters and converters