Developer Tools
Everyday utilities for working with data formats, encodings and identifiers. Everything runs locally in your browser, so API responses, tokens and config files you paste here are never uploaded.
All 132 developer tools
Grouped by what they do.
JSON & data formats
22 toolsWork with structured data: check it, tidy it, query it or change its format.
- JSON Formatter Pretty-print, minify and fix JSON with exact error locations.
- JSON Validator Strict JSON validation with exact error locations and every path listed.
- CSV to JSON Converter Two-way CSV ⇄ JSON with delimiter detection, safe typing and a preview table.
- XML Formatter Pretty-print or minify XML and find syntax errors by line and column.
- Comma Separated List Converter Column to comma list and back — or SQL IN, JSON, Python and CSV — in one paste.
- JSON Viewer & Tree Editor Browse, search and edit big JSON files in a fast tree — and copy any path.
Show all 22 Show fewer JSON & data formats tools
- JSON ↔ YAML Converter Two-way JSON ⇄ YAML conversion that keeps numbers exact and warns about YAML traps.
- HTML / Web Table to CSV & Excel Copy a table from any web page, Word file or Wikipedia article — get clean CSV or Excel.
- YAML Validator & Formatter Find YAML errors by line, catch YAML 1.1 traps, check Compose and Actions files, format.
- CSV to SQL Converter Typed CREATE TABLE and batched INSERTs, upserts or bulk-load scripts for six databases.
- Excel to JSON Converter Spreadsheet rows to clean, typed JSON — header row as keys, dates as ISO 8601.
- XML ↔ JSON Converter Two-way XML ⇄ JSON with control over attributes, arrays and namespaces — XXE-safe.
- JSON Schema Validator Check JSON against a schema and get every error with its path, line and a clear fix.
- JSON to Excel Converter API responses and nested JSON to a clean Excel workbook — one sheet per list.
- Table Converter Paste a table in any common format, tidy it in a grid, export it in 29 formats.
- JSON Diff & Compare Structural JSON compare with JSON Patch and Merge Patch export — and apply patches too.
- TOML ↔ JSON Converter Exact TOML ⇄ JSON / YAML conversion, with errors that name the rule and the line.
- XSD Validator Check XML against an XML Schema and get every error with its line, path and a clear fix.
- JSON Schema Generator Paste JSON samples and get a JSON Schema that accepts them, ready to refine.
- JSONPath & JMESPath Tester Standard JSONPath and AWS-style JMESPath queries, evaluated live on your JSON.
- JSON Repair Tool Turns almost-JSON into valid JSON — and shows exactly what it changed.
- Text to PDF Converter Plain text, logs and code to a clean PDF — with headers, page and line numbers.
Formatters & minifiers
9 toolsMake code readable, or compact for production.
- SQL Formatter Readable, consistently indented SQL for 20 dialects — or a safe one-line copy.
- HTML Formatter Indent messy markup cleanly, or minify it without breaking pre, textarea or scripts.
- CSS Formatter Pretty-print CSS for reading, or minify it for production — without breaking it.
- JavaScript Formatter Turn minified or messy JavaScript into readable, consistently indented code.
- SVG Optimizer Shrink SVG icons and illustrations with SVGO — previewed safely, nothing uploaded.
- JavaScript Minifier Shrink JavaScript for production with Terser, in your browser, with a source map.
Show all 9 Show fewer Formatters & minifiers tools
- CSS Toolkit Four everyday CSS jobs in one place: specificity, validation, media queries and variables.
- JavaScript Obfuscator Make JavaScript hard to read: renamed names, encoded strings, flattened control flow.
- Code Formatter (TypeScript, Vue, Markdown & more) Prettier for 18 languages — auto-detected, configurable, with a diff of every change.
Encode, decode & hash
19 toolsTurn data into a safe or compact form and back, or fingerprint it.
- Base64 Encoder & Decoder Text and files to Base64 and back — UTF-8 safe, URL-safe, data URIs.
- URL Encoder & Decoder Percent-encode and decode safely, and see every part of a URL.
- JWT Decoder Read any JWT and check its signature — without sending the token anywhere.
- Hash Generator Hashes and HMACs of text or huge files, plus checksum verification.
- SSL Certificate Decoder Paste a certificate, a chain or a CSR: every field decoded, every problem explained.
- Text to Binary & Hex Converter See the exact bytes behind any text, and turn binary or hex dumps back into text.
Show all 19 Show fewer Encode, decode & hash tools
- URL Extractor Every link in a page’s source or any text — cleaned up, counted and filterable.
- Bcrypt Hash Generator & Verifier Create and verify bcrypt hashes in your browser, with timing and the 72-byte check.
- HTML Entity Encoder & Decoder Escape text for HTML, or decode &, © and → exactly as a browser would.
- Image to Base64 Converter Inline images as data URIs — optimised first, with snippets ready to paste.
- Argon2 Hash Generator & Verifier Argon2id hashes with OWASP and RFC 9106 settings, made and checked on your device.
- Encoding Toolkit (All-in-one) Every encoding side by side — paste anything and it works out how to decode it.
- JWT Encoder & Signer Sign a JWT with any standard algorithm — the key never leaves this page.
- Unicode Character Inspector Paste text to see each character — and the invisible or look-alike ones hiding in it.
- AES Encryption Tool (Developer) AES-GCM, CBC and CTR with raw keys, for test vectors and interoperability debugging.
- String Escape / Unescape Escape text for 11 languages and formats, or turn escapes back into text.
- Text Encoding Converter & Mojibake Fixer Read old text files correctly, save them as UTF-8, and un-garble “café”.
- CRC Calculator (CRC-8/16/32/64) Every catalogued CRC, custom parameters, checksums and C code — for text, hex or files.
- Image to C Array (Arduino Displays) Images as C arrays for OLED, e-paper and TFT screens, with a byte-exact preview.
Code converters
12 toolsStart from one language or format and get working code in another.
- JSON to TypeScript Paste JSON, get TypeScript types (and a Zod schema) that fit every sample.
- Markdown to HTML Markdown (or BBCode) in, clean and safe HTML out — with a live preview.
- JSON to Go Struct Paste JSON, get Go structs with json tags that unmarshal it.
- JSON to C# Class Paste JSON, get C# classes with the right serializer attributes.
- JSON to Java Class (POJO) Paste JSON, get Java classes (one file each) that Jackson can read.
- cURL to Code Converter Paste a curl command, get the same request in your language.
Show all 12 Show fewer Code converters tools
- Word to HTML Converter Paste from Word or Google Docs, or open a .docx — get clean, semantic HTML or Markdown.
- JSON to Code Generator Paste JSON, get model classes for Python, Kotlin, Swift, Dart, Rust and 19 more.
- HTML to JSX Converter Paste HTML or SVG, get React JSX that renders exactly the same.
- Docker Run to Docker Compose Converter Paste docker run commands, get a Compose file — or turn a Compose file into commands.
- HTML to PDF Converter HTML code, a saved web page or a ZIP of one — to a PDF, safely and privately. Pro tool
- HTML to Markdown Converter Paste HTML or formatted text and get clean, GitHub-ready Markdown.
Test & debug
14 toolsTry out patterns, requests and documents before they go into your code.
- Regex Tester Live matches, capture groups and replace preview — safe from runaway patterns.
- Text Diff See what changed between two versions — by line, word or character.
- Security Headers Checker Grade a site’s security headers A+ to F and get copy-paste fixes for your server.
- LLM Token Counter Exact token counts for OpenAI and open models — your text never leaves the browser.
- User Agent Parser See which browser, OS, device or bot sent a request: one user agent or a whole log.
- Schema Markup Validator Find syntax errors, schema.org mistakes and missing Google properties in your markup.
Show all 14 Show fewer Test & debug tools
- Color Contrast Checker (WCAG 2.2) Test text and background colors against WCAG 2.2, then fix them in one click.
- Find and Replace Text Many find-and-replace rules at once, with regex, case options and highlighted changes.
- JavaScript Keycode Finder Press a key: get its key, code and keyCode, plus listener code ready to paste.
- REST API Tester (Online API Client) A Postman-style API client in this tab — requests go straight from you to the API. Pro tool
- Card & Check-digit Validator Is the number well formed? Luhn, GS1 and ISBN check digits, worked out step by step.
- OpenAPI / Swagger Editor & Validator Paste an API description: see every problem by line, the API reference and curl commands.
- Hex Viewer & File Inspector A private hex viewer for files of any size, with a data inspector and file-type detection.
- WebSocket & SSE Tester An online WebSocket and event-stream client — straight from your browser to your server.
Editors & playgrounds
6 toolsWrite and run code or diagrams right in the page.
- Markdown Editor Write Markdown and see it formatted as you type — kept in your browser, never uploaded.
- HTML, CSS & JS Playground (Online Editor) A CodePen-style editor with live preview and console — private, sandboxed, no sign-up. Pro tool
- JavaScript & TypeScript Online Compiler Write, run and debug JS or TS snippets — safely sandboxed, nothing to install.
- Python Online Compiler Real CPython in your browser — with stdin, files and a stop button.
- SQLite Online (SQL Playground) A full SQLite database in your browser — open, query, import, export. Pro tool
- CSS Flexbox Generator & Playground Try every flexbox property on live boxes, understand the result and copy the code.
Generators
40 toolsGet identifiers, sample data and boilerplate without writing them by hand.
- UUID Generator Random v4 and time-ordered v7 UUIDs, in bulk — plus a UUID inspector.
- Password Generator Strong random passwords and passphrases, generated only on your device.
- Code Screenshot Generator Carbon-style code images with VS Code themes — made in your browser.
- Content Security Policy (CSP) Generator Build a strict, working CSP with hashes, reporting and ready-to-paste server config.
- Tailwind Color Palette Generator (50–950) One brand color in, an 11-step Tailwind shade scale out — with contrast for every shade.
- .gitignore Generator Combine official templates, add your rules, and check any path the way git does.
Show all 40 Show fewer Generators tools
- CSR Generator A key and a CSR for your SSL certificate, made on your device — the key never leaves it.
- HTML Table Generator Spreadsheet-style editing, accessible table markup out — styled, responsive and sortable.
- UI Color Theme Generator (shadcn, Tailwind, Material 3) Brand color in, full light and dark theme out — every text pair checked for contrast.
- CSS Gradient Generator Drag color stops, blend in OKLCH or sRGB, and copy the CSS — or save it as a wallpaper.
- RSA Key Pair Generator RSA key pairs in every format — PEM, JWK, SSH — made in your browser, self-tested.
- API Key & Secret Generator Cryptographically random API keys and framework secrets, made only on your device.
- CSS Box Shadow Generator Stack shadow layers visually and copy clean CSS, a Tailwind class or a whole shadow scale.
- CSS Grid Generator Paint named areas, size the tracks and get responsive CSS grid code, HTML or Tailwind.
- Cron Expression Generator & Explainer Write, check and translate cron schedules — and see exactly when they run.
- HMAC Generator Keyed hashes for API and webhook signatures — compute, verify and get the code.
- Markdown Table Generator Spreadsheet-style editing for GitHub Markdown tables, with a live preview.
- Mock Data Generator Design the columns, link the tables, and download up to a million rows of test data. Pro tool
- Glassmorphism CSS Generator Frosted glass over any background, with a text-contrast check that sees through the blur.
- TOTP / HOTP Code Generator Live 2FA codes from a secret, setup QR codes and authenticator backups, on your device.
- Background Pattern Generator (CSS & SVG) Fifteen seamless patterns with your colors, size and angle — as CSS, SVG or PNG.
- Neumorphism (Soft UI) Generator Paired light and dark shadows from one base color, with an honest contrast check.
- PDF to Markdown Converter Turn a PDF into Markdown or HTML — headings, lists, tables, code and pictures included. Pro tool
- .htpasswd Generator Password lines and config for Apache and nginx Basic authentication, made on your device.
- CSS Clip-Path Generator Draw a clip-path by dragging points, round its corners and wrap text around it.
- Markdown to PDF Converter Markdown in, a clean, print-ready PDF out — tables, code, footnotes and all.
- SVG Wave & Section Divider Generator Make layered waves, curves, tilts and arrows to divide page sections — copy SVG or CSS.
- NanoID, ULID & Snowflake ID Generator Every popular ID format in bulk — and the creation time inside the ones you already have.
- SVG Blob Generator Generate smooth organic blobs from a seed, fill them, and animate one blob into another.
- CSS Text Shadow Generator Stack text-shadow layers on your own words and font, check contrast, copy CSS or Tailwind.
- Cubic Bezier & CSS Easing Generator Shape an easing curve, watch it race the classics and copy CSS, Tailwind or JavaScript.
- Random String & Code Generator Unique coupon, voucher and invite codes, PINs and test IDs — up to 100,000 at a time.
- CSS Animation & Keyframes Generator Design keyframe animations visually and copy accessible CSS or a Tailwind theme snippet.
- CSS Border Radius Generator Round each corner, or drag eight radii into organic shapes — then copy CSS or Tailwind.
- Elliptic Curve Key Generator (ECDSA / Ed25519 / X25519) EC key pairs in PEM, JWK, raw hex and OpenSSH formats, generated in your browser.
- SVG Shape Generator (Polygon, Star, Badge) Parametric vector shapes with real rounded corners — as SVG, clip-path or PNG.
- Squircle & Smooth Corner Generator Smooth, continuous corners for icons, cards and buttons — as SVG or CSS.
- Apache .htaccess Generator Pick what your site needs and get a commented .htaccess file, with the modules it needs.
- CSS Loader & Spinner Generator Lightweight loading spinners in one element, accessible and motion-friendly.
- Custom Scrollbar CSS Generator Custom scrollbars that work in every browser, previewed in a scrolling box.
Calculators & reference
10 toolsQuick lookups and conversions that come up while coding.
- Timestamp Converter Epoch time ⇄ readable dates in any time zone, with daylight saving handled.
- Color Converter Every color format at once, with WCAG contrast checks, tints and shades.
- Chmod Calculator Work out chmod numbers, symbolic modes and umask results, with warnings for risky modes.
- HTTP Status Codes Reference Every HTTP status code explained: what it means, why you got it and how to fix it.
- Number Base Converter Binary, octal, decimal, hex and every base to 36 — exact, with the working shown.
- PX to REM Converter px ⇄ rem, em and every CSS length unit — or convert a whole stylesheet at once.
Show all 10 Show fewer Calculators & reference tools
- MIME Type Lookup The right Content-Type for any file — and whether a file really is what its name says.
- Programmer Calculator (Bitwise) Bitwise maths at a real bit width — with overflow, endianness and every base at once.
- IEEE 754 Floating-Point Converter See exactly how a number is stored in binary floating point — every bit, every digit.
- Color Temperature (Kelvin) to RGB Converter See what color a light of any temperature is, and how warm or cool a color is.
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Developer tools A–Z
A
B
C
- Card & Check-digit Validator
- Chmod Calculator
- Code Formatter (TypeScript, Vue, Markdown & more)
- Code Screenshot Generator
- Color Contrast Checker (WCAG 2.2)
- Color Converter
- Color Temperature (Kelvin) to RGB Converter
- Comma Separated List Converter
- Content Security Policy (CSP) Generator
- CRC Calculator (CRC-8/16/32/64)
- Cron Expression Generator & Explainer
- CSR Generator
- CSS Animation & Keyframes Generator
- CSS Border Radius Generator
- CSS Box Shadow Generator
- CSS Clip-Path Generator
- CSS Flexbox Generator & Playground
- CSS Formatter
- CSS Gradient Generator
- CSS Grid Generator
- CSS Loader & Spinner Generator
- CSS Text Shadow Generator
- CSS Toolkit
- CSV to JSON Converter
- CSV to SQL Converter
- Cubic Bezier & CSS Easing Generator
- cURL to Code Converter
- Custom Scrollbar CSS Generator
E
H
- Hash Generator
- Hex Viewer & File Inspector
- HMAC Generator
- HTML / Web Table to CSV & Excel
- HTML Entity Encoder & Decoder
- HTML Formatter
- HTML Table Generator
- HTML to JSX Converter
- HTML to Markdown Converter
- HTML to PDF Converter Pro tool
- HTML, CSS & JS Playground (Online Editor) Pro tool
- .htpasswd Generator
- HTTP Status Codes Reference
J
- JavaScript & TypeScript Online Compiler
- JavaScript Formatter
- JavaScript Keycode Finder
- JavaScript Minifier
- JavaScript Obfuscator
- JSON ↔ YAML Converter
- JSON Diff & Compare
- JSON Formatter
- JSON Repair Tool
- JSON Schema Generator
- JSON Schema Validator
- JSON to C# Class
- JSON to Code Generator
- JSON to Excel Converter
- JSON to Go Struct
- JSON to Java Class (POJO)
- JSON to TypeScript
- JSON Validator
- JSON Viewer & Tree Editor
- JSONPath & JMESPath Tester
- JWT Decoder
- JWT Encoder & Signer
M
P
R
S
T
U
Collections with developer tools
All collections →- 197 tools Developers JSON, YAML & data formats · Format, convert & run code · Encode, decode & hash · 5 more
- 174 tools Students Grades, marks & exams · Essays & writing · Citations & references · 4 more
- 101 tools Finance & CA Income tax & TDS · GST & compliance · Returns & valuation · 4 more
- 118 tools Creators & social media Posts, captions & hashtags · YouTube · Images & graphics · 3 more
Good to know
- 127 of 132 tools run entirely in your browser; the other 5 explain on their pages what they send.
- 118 of 132 keep working without a connection once loaded.
- 17 of 132 tools use the network for part of their work; each one says on its page what it sends and where.
Other categories
All tools →- 40 tools Data CSV, Excel, tables, charts.
- 95 tools Text Count, clean, sort, compare.
- 92 tools Image Compress, resize, convert, crop.
- 55 tools PDF Merge, split, extract, convert.
- 35 tools Audio & Video Convert, trim, compress media.
- 56 tools Design Colours, gradients, CSS.
- 36 tools SEO Meta tags, sitemaps, schema.
- 27 tools Social Media Captions, previews, limits.
- 94 tools Finance Loans, savings, interest, tax.
- 78 tools Business Invoices, quotes, margins.
- 39 tools Legal Templates and legal maths.
- 48 tools Health BMI, calories, pregnancy.
- 51 tools Math Calculators and solvers.
- 45 tools Science Physics, chemistry, astronomy.
- 31 tools Engineering Electronics, electrical, mechanical.
- 29 tools Construction Materials, area, home costs.
- 80 tools Education Grades, citations, study.
- 36 tools Network DNS, headers, IPs, subnets.
- 35 tools Security Passwords, encryption, keys.
- 33 tools Converters Every unit, exact factors.
- 75 tools Utility Convert, count down, randomise.