Free Online Developer Tools

Your Swiss Army Knife for Development

Free developer tools covering 100+ use cases — all running in your browser. No sign-up, no tracking, no server processing.

81 tools

Crypto & Hash

SHA Hash & HMAC Generator

Generate SHA-1, SHA-256, SHA-384, SHA-512 hashes and HMAC signatures with this free online tool. No sign-up required, runs entirely in your browser.

Secure Password Generator

Generate strong, random passwords with customizable length and character sets using this free online tool. No sign-up required, runs entirely in your browser.

UUID v4 & v7 Generator

Generate UUID v4 (random) and UUID v7 (timestamp-based) identifiers in bulk with this free online tool. No sign-up required, runs entirely in your browser.

Bcrypt Hash Generator & Verifier

Generate and verify bcrypt password hashes with adjustable cost factor using this free online tool. No sign-up required, runs entirely in your browser.

AES Encryption & Decryption Tool

Encrypt and decrypt text with AES-GCM or AES-CBC using this free online tool. Password-based key derivation via PBKDF2. No sign-up required, runs entirely in your browser.

TOTP Authenticator — Two-Factor Code Generator

Free online TOTP authenticator that generates time-based one-time passwords. Supports SHA-1, SHA-256, SHA-512 algorithms. No sign-up, runs in your browser.

X.509 Certificate Decoder

Free online X.509 certificate decoder. Parse PEM certificates to view subject, issuer, validity, SAN, fingerprints, and extensions. No sign-up required.

Ed25519 Key Generator — Sign & Verify

Free online Ed25519 key pair generator with message signing and signature verification. Uses the Web Crypto API. No sign-up, runs in your browser.

BIP39 Mnemonic Generator — Seed Phrase Creator

Free online BIP39 mnemonic generator. Create 12-24 word seed phrases with cryptographic entropy and checksum validation. No sign-up, runs in your browser.

PGP Encryption & Decryption — OpenPGP Online

Free online PGP encryption and decryption tool powered by OpenPGP.js. Encrypt messages with public keys, decrypt with private keys, and generate ECC/RSA key pairs. No sign-up required.

Encoders & Converters

Base64 String Encoder & Decoder

Encode and decode Base64 strings instantly with this free online converter. Supports standard and URL-safe Base64. No sign-up required, runs entirely in your browser.

URL Encoder & Decoder — Free Online

Encode and decode URLs instantly with this free online tool. Supports encodeURIComponent and encodeURI modes for query strings and full URLs. No sign-up required.

Base64 File Converter — Free Online

Convert files to Base64 and Base64 back to files with this free online tool. Supports images, PDFs, and any binary file. No sign-up required.

HTML Entity Encoder & Decoder — Free Online

Encode and decode HTML entities instantly with this free online tool. Escape special characters to prevent XSS and display issues. No sign-up required.

Number Base Converter

Free online number base converter. Convert between binary, octal, decimal, hexadecimal, and any base from 2 to 36 instantly.

.env / YAML / JSON Converter — Free Online

Convert between .env, JSON, and YAML formats instantly with this free online converter. Transform environment variable files, configuration formats, and dotenv files with one click.

Text Encoder Explorer — Unicode, UTF-8, UTF-16 Byte Inspector

Explore how text is encoded in UTF-8, UTF-16, and Unicode code points. View per-character byte breakdowns, hex dumps, and encoding statistics. Free online tool, runs entirely in your browser.

Web & Auth

JWT & Bearer Token Inspector - Decode JSON Web Tokens

Free online JWT decoder and Bearer token inspector. Decode JWT headers, payloads, and check expiration claims instantly in your browser.

QR Code Generator & Reader

Free online QR code generator and reader. Create QR codes from text or URLs and decode QR codes from uploaded images instantly.

URL Parser - Parse & Analyze URL Components Online

Free online URL parser tool. Break down any URL into its components — protocol, hostname, port, path, query parameters, and hash fragment.

HTTP Request Builder

Free online HTTP request builder. Visually construct API requests and generate ready-to-use curl, fetch, and axios code snippets.

HTTP Status Codes Reference - Complete Status Code Guide

Free online HTTP status codes reference. Search and browse all HTTP response status codes with descriptions, categories, and common use cases.

Basic Auth Generator & Decoder - HTTP Authorization Header

Free online Basic Auth header generator and decoder. Create HTTP Basic Authorization headers from credentials or decode existing headers instantly.

OAuth2 Token Debugger - Decode Tokens & Parse Auth URLs

Free online OAuth2 token debugger. Decode JWT access tokens and id tokens, parse OAuth2 authorization URLs, and inspect OIDC parameters.

OG Meta Tag Preview

Free online Open Graph meta tag preview tool. See how your page looks on Google, Facebook, Twitter, and LinkedIn before publishing.

Cookie Parser

Free online cookie parser tool. Parse and inspect Set-Cookie headers and document.cookie strings to view names, values, and attributes.

CORS Header Checker

Free online CORS header checker and analyzer. Validate Access-Control headers, diagnose cross-origin issues, and verify preflight configuration.

OpenAPI / Swagger Viewer

Free online OpenAPI 3.x viewer. Paste YAML or JSON to visualize API endpoints, parameters, responses, and schemas. No sign-up required.

CSP Header Builder

Free online Content Security Policy (CSP) header builder and generator. Visually configure CSP directives, validate policies, and test URLs against your security rules.

SAML Response Decoder - Decode & Format SAML XML

Free online SAML response decoder. Decode Base64-encoded SAML responses, format the XML output, and inspect SSO assertions instantly.

robots.txt & Sitemap Validator - Validate Robots Rules & Sitemap XML Online

Free online robots.txt and sitemap.xml validator. Parse and validate robots.txt directives, test URL access rules, and verify sitemap XML structure, URLs, and metadata.

HTTP Header Parser - Analyze & Inspect HTTP Headers Online

Free online HTTP header parser tool. Parse raw HTTP headers, inspect key-value pairs, and check security headers like CSP, HSTS, X-Frame-Options, and more.

Device Information - Browser, Screen & Hardware Details

View detailed device and browser information including user agent, screen resolution, GPU, CPU cores, memory, connection type, and more — all detected in real time.

Development

Regex Tester & Debugger

Free online regex tester to match, replace, and debug regular expressions with real-time highlighting and capture group support.

Unix Timestamp Converter

Free online Unix timestamp converter to convert between epoch timestamps and human-readable dates in ISO, UTC, and local formats.

Color Converter & Picker

Free online color converter and picker tool to convert between HEX, RGB, and HSL formats with a visual color preview.

Crontab Generator & Explainer

Free online crontab expression generator and explainer. Build cron schedules visually or paste an expression to get a plain-English description.

Text Diff Viewer & Comparator

Free online diff viewer to compare two texts side by side or in unified format, highlighting additions, deletions, and changes instantly.

Text Case & Format Converter

Free online text case converter to transform text between camelCase, snake_case, PascalCase, kebab-case, and 10+ other formats instantly.

Chmod Permission Calculator

Free online chmod calculator to set Unix/Linux file permissions. Convert between octal, symbolic notation, and get the chmod command instantly.

Docker Run to Compose Converter

Free online tool to convert docker run commands to docker-compose.yml format. Instantly transform container commands into composable YAML configurations.

Code Formatter — Prettier Online

Free online code formatter powered by Prettier. Format JavaScript, TypeScript, HTML, Vue, CSS, SCSS, JSON, YAML, Markdown, and GraphQL with customizable options. No sign-up required.

Fake Data Generator

Generate realistic fake data for testing and development — names, emails, addresses, phone numbers, UUIDs, and more. Powered by Faker.js with multi-locale support.

URL Slug Generator

Free online URL slug generator. Convert any text to SEO-friendly, URL-safe slugs with customizable separators, case options, and length limits.

CSS Unit Converter

Free online CSS unit converter. Convert between px, rem, em, pt, %, vw, and vh with customizable base font size and viewport dimensions.

Lorem Ipsum Generator

Free online Lorem Ipsum placeholder text generator. Generate dummy text by paragraphs, sentences, or words for mockups and designs.

Mermaid Live Editor — Diagram Generator

Free online Mermaid diagram editor. Create flowcharts, sequence diagrams, class diagrams, Gantt charts, pie charts, and mind maps. Export to SVG or PNG. No sign-up required.

Accessibility Color Contrast Checker

Free online WCAG color contrast checker. Calculate contrast ratios, verify AA/AAA compliance, preview text readability, and simulate color blindness for accessible design.

Date-Time Converter with Timezone Support

Free online date-time converter to convert dates and times across timezones. Supports ISO 8601, RFC 2822, Unix timestamps, and relative time — powered by native Intl APIs.

Git Cheatsheet - Quick Command Reference & Memo

Free online Git cheatsheet with searchable commands organized by category. Quickly find Git commands for branching, merging, rebasing, stashing, resetting, and more.

Git Commit Message Generator

Free online Git commit message generator using the Conventional Commits format. Build structured commit messages with type, scope, description, body, breaking changes, and footer fields.

Nginx Config Generator

Free online Nginx configuration file generator. Build server blocks with SSL, reverse proxy, gzip, security headers, WebSocket support, and more — no manual editing required.

Dockerfile Linter

FILETIME & LDAP Timestamp Converter

Free online FILETIME and LDAP/Active Directory timestamp converter. Convert 18-digit Windows FILETIME to human-readable dates and back. Live clock included.

Color Space Explorer — OKLCH, OKLab, P3 & More

Free online extended color space converter. Convert between HEX, RGB, HSL, HWB, OKLab, OKLCH, Linear sRGB, and Display P3 with CSS output. No sign-up required.

Tailwind CSS Class Sorter — Organize Utility Classes

Free online Tailwind CSS class sorter. Organize utility classes following the official recommended order with duplicate removal. No sign-up required.

Benchmark Builder — JavaScript Performance Testing

Free online JavaScript benchmark tool. Compare code snippet performance with operations-per-second metrics and visual bar charts. No sign-up required.

Figma Token Converter — Design Tokens to CSS/Tailwind

Free online Figma design token converter. Transform JSON design tokens to CSS custom properties, SCSS variables, Tailwind config, or JS exports. No sign-up required.

GraphQL Playground — Schema Validator & Query Formatter

Free online GraphQL playground. Validate queries against your schema, format GraphQL queries, and inspect schema types. Works offline, no sign-up required.

Network

CIDR Calculator & Subnet Visualizer

Free online CIDR calculator. Compute network address, broadcast, subnet mask, host range, and total hosts from any CIDR notation.

Text

Markdown Preview & Editor

Free online Markdown editor with live preview. Write and preview Markdown with GFM support, tables, code blocks, and more — all in your browser.

Markdown Table Generator — Free Online GFM Table Builder

Generate well-formatted GitHub Flavored Markdown (GFM) tables with an interactive visual editor. Set column alignment, add or remove rows and columns, and copy the output instantly.

Emoji Picker & Search

Free online emoji picker and search tool. Browse, search, and copy emojis by category — smileys, animals, food, symbols, flags, and more. Click any emoji to copy it to your clipboard instantly.

ASCII Text Drawer / Art Generator

Free online ASCII art text generator. Convert any text into large block letters, shadow art, or simple ASCII banners — no external libraries required.

Email Normalizer

Normalize and deduplicate email addresses by removing dots, plus aliases, and provider-specific suffixes to find canonical forms.

Unicode Character Lookup — Code Point Inspector

Free online Unicode character lookup tool. Inspect text to see code points, UTF-8/UTF-16 encoding, Unicode block, and category. Search by U+ code point. No sign-up required.

HTML WYSIWYG Editor — Rich Text to HTML

Free online WYSIWYG HTML editor. Create rich text content with formatting tools and get clean HTML output. Supports headings, lists, code blocks, blockquotes, and more. No sign-up required.

Data Formats

JSON Formatter & Viewer — Free Online

Format, prettify, minify, and validate JSON instantly with this free online JSON formatter. Adjust indentation, sort keys, and view stats in real time.

Data Format Converter — Free Online

Convert between JSON, YAML, TOML, and CSV instantly with this free online data format converter. Swap formats with one click, no sign-up required.

JSON Schema Generator & Validator — Free Online

Generate JSON Schema from sample data or validate JSON against a schema with this free online tool. Uses Ajv for validation. No sign-up required.

CSV Viewer & Editor — Free Online

View, edit, sort, and export CSV data in a spreadsheet-like table. Supports custom delimiters (comma, tab, semicolon, pipe). Powered by PapaParse — no data leaves your browser.

SQL Formatter & Beautifier — Free Online

Format, beautify, and pretty-print SQL queries instantly. Supports MySQL, PostgreSQL, SQLite, T-SQL, PL/SQL, MariaDB, BigQuery, and standard SQL with customizable indentation and keyword casing.

Protobuf to JSON Converter

Free online Protocol Buffers (Protobuf) to JSON converter. Encode JSON to Protobuf binary and decode Protobuf binary back to JSON. Paste your .proto schema and data. No sign-up required.

Images & Videos

SVG Optimizer & Viewer — SVGO Online

Free online SVG optimizer powered by SVGO. Compress SVG files, remove metadata, and preview results side-by-side. No sign-up required.

Favicon Generator — Multi-Size Icon Creator

Free online favicon generator. Upload an image to create favicons in all standard sizes (16x16 to 512x512) with HTML and manifest snippets. No sign-up required.

Image/Color Placeholder Generator

Free online placeholder image generator. Create custom colored placeholder images with text overlay in SVG or PNG format for mockups, wireframes, and prototyping.

Camera Recorder — Webcam Video Capture

Free online camera recorder. Record video from your webcam with optional audio, pause/resume, and download as WebM. No sign-up, runs in your browser.

Math

Percentage Calculator

Free online percentage calculator. Compute X% of Y, find what percent X is of Y, calculate percentage change, and increase or decrease values by a percentage.