91 free developer tools that stay on your device

JSON Formatter

Beautify, minify, and validate JSON. Catch syntax errors with line-precise feedback.

Base64 Encode / Decode

Encode text to Base64 or decode Base64 back to UTF-8 text.

JWT Decoder

Decode JWT header and payload, inspect claims and expiration — locally in your browser.

UUID Generator

Generate v4, v7, and nil UUIDs in bulk.

Regex Tester

Test JavaScript regular expressions with live match highlighting.

Hash Calculator

Generate MD5, SHA-1, SHA-256, SHA-512 and Blake3 hashes from text.

Unix Timestamp Converter

Convert Unix timestamps to human-readable dates and back.

Color Converter

Convert between HEX, RGB, HSL with live swatch preview.

JSON Formatter

Beautify, minify, and validate JSON. Catch syntax errors with line-precise feedback.

XML Formatter

Pretty-print and minify XML documents with proper indentation.

YAML Formatter

Validate and reformat YAML with consistent indentation for configs and CI files.

TOML Formatter

Pretty-print and validate TOML configuration files used by Rust, Python, and CLIs.

SQL Formatter

Beautify SQL queries with dialect-aware formatting (MySQL, Postgres, etc.).

CSS Formatter

Beautify or minify CSS with Prettier-powered formatting.

JavaScript Formatter

Beautify or minify JavaScript / TypeScript using Prettier.

HTML Formatter

Beautify or minify HTML documents with Prettier.

Config Format Converter

Convert between JSON, YAML, TOML, and XML configuration formats.

JSON ↔ CSV

Convert JSON arrays to CSV and back, with header detection.

Color Converter

Convert between HEX, RGB, HSL with live swatch preview.

Unix Timestamp Converter

Convert Unix timestamps to human-readable dates and back.

Case Converter

Convert text between camelCase, snake_case, kebab-case, PascalCase, etc.

Number Base Converter

Convert numbers between binary, octal, decimal, and hex.

CSS Gradient Builder

Visually build linear, radial, and conic gradients with multiple color stops.

JSON → TypeScript

Generate TypeScript interfaces from JSON objects. Nested objects become separate types.

JSON Sorter

Sort JSON keys alphabetically, flatten nested objects, or unflatten dotted keys.

File Size Converter

Convert between bytes, KB, MB, GB, TB, KiB, MiB, GiB. Includes download time estimates.

CSS Unit Converter

Convert between px, rem, em, pt, in, cm, mm, vw, vh, and %. Configurable root font size.

Slug Generator

Convert titles to URL-safe slugs. Configurable separator, case, stop words, max length.

Image ↔ Base64

Convert images to Base64 data URLs and back. Drag-and-drop, preview, download.

Time Zone Converter

Convert a date/time across 18 common time zones with live current-time ticker and DST detection.

Unicode Lookup

Search Unicode characters by char, codepoint, or name. Browse by block. Copy as HTML/JS/CSS.

JSON Diff

Deep-compare two JSON objects and see added, removed, and changed paths side-by-side.

JSON → Go

Generate Go structs from JSON with JSON tags. snake_case keys become PascalCase.

JSON → Zod

Generate Zod schemas from JSON. Auto-detects dates, UUIDs, emails, URLs. With z.coerce option.

Color Contrast Checker

Check WCAG 2.1 contrast ratio between two colors. Get AA/AAA pass/fail for normal and large text.

Box Shadow Generator

Visually build CSS box-shadows with multiple layers, inset, spread, and color (with alpha). 6 presets.

Markdown Table Generator

Convert CSV / TSV / spreadsheet data to a Markdown table with per-column alignment control.

Code Screenshot

Generate beautiful code screenshots (carbon-style) with syntax highlighting, themes, and window controls.

Regex Visualizer

Visualize a regex as a Thompson NFA state machine graph. See states, transitions, and epsilon moves.

CSS Animation Generator

Visually build CSS @keyframes animations with 8 presets, timing functions, and live preview.

SVG Icon Browser

Browse 184 curated SVG icons (Lucide-style). Adjust size, stroke, color, fill. Copy as SVG or React.

CSS Flexbox Generator

Visually build flexbox layouts. Adjust direction, justify, align, wrap, gap. Live preview + CSS.

CSS Grid Generator

Visually build CSS Grid layouts. Adjust columns, rows, gap, alignment. Live preview + CSS.

Border Radius Generator

Visually build CSS border-radius. Per-corner control, 8 presets (Pill, Blob, Leaf, Ticket, Wave).

CSS Filter Generator

Visually build CSS filters: blur, brightness, contrast, grayscale, hue-rotate, sepia, more.

JSON → Python

Generate Python @dataclass classes from JSON. Type hints, snake_case keys, nested classes.

CSS Transform Generator

Visually build CSS transforms: rotate, scale, skew, translate. Live preview with sliders.

Placeholder Image Generator

Generate placeholder images with custom dimensions, colors, and text. Download as PNG.

Markdown → HTML

Convert Markdown to clean HTML with live preview. Supports headings, tables, code blocks, links.

HTML → Markdown / JSX

Convert HTML to Markdown or React JSX. Maps class→className, styles, and void tags correctly.

User Agent Parser

Parse User-Agent strings to detect browser, OS, device type, and rendering engine.

CIDR / IP Subnet Calculator

Calculate network, broadcast, netmask, usable hosts, and binary masks from an IPv4 CIDR.

Base64 Encode / Decode

Encode text to Base64 or decode Base64 back to UTF-8 text.

URL Encode / Decode

Percent-encode or decode URLs and query components.

HTML Entity Encode / Decode

Escape or unescape HTML entities (& < > etc.).

JWT Decoder

Decode JWT header and payload, inspect claims and expiration — locally in your browser.

JWT Signer

Sign JWTs with HS256 / HS384 / HS512 using the browser's native Web Crypto API.

JWT Key Generator

Generate HMAC secrets, RSA key pairs, and ECDSA key pairs for JWT signing. PEM output.

Hash Calculator

Generate MD5, SHA-1, SHA-256, SHA-512 and Blake3 hashes from text.

Hash Identifier

Detect the type of a hash (MD5, SHA-1, SHA-256, bcrypt, Argon2, UUID, etc.) by pattern.

File Hash Calculator

Drag a file in and compute MD5, SHA-1, SHA-256, SHA-512, Blake3 checksums.

UUID Generator

Generate v4, v7, and nil UUIDs in bulk.

Password Generator

Generate strong, configurable passwords with entropy meter.

Bcrypt Hash Generator

Generate and verify bcrypt password hashes with adjustable cost factor (4–14).

HMAC Generator

Generate HMAC-SHA1/256/384/512 signatures for API request signing. UTF-8/hex/base64 input.

TOTP / 2FA Generator

Generate live TOTP codes from a Base32 secret or otpauth:// URI. SHA-1/256/512, local-only.

PEM / X.509 Certificate Decoder

Decode PEM or base64 X.509 certificates — subject, issuer, SANs, dates, fingerprints.

Regex Tester

Test JavaScript regular expressions with live match highlighting.

Diff Checker

Compare two text blocks side-by-side with character-level diff.

Markdown Previewer

Write Markdown on the left, see rendered HTML on the right.

Lorem Ipsum Generator

Generate placeholder text by paragraphs, sentences, or words.

Text Statistics

Count words, characters, sentences, paragraphs and reading time.

Character Counter

Live character, word and line count for any input.

String Reverser

Reverse text by characters, words, or lines.

HTTP Status Codes

Searchable reference of all HTTP status codes with meanings.

ASCII Table

Full ASCII character reference with decimal, hex, and binary.

MIME Types

Searchable database of file extensions and MIME types.

QR Code Generator

Generate QR codes from any text or URL with adjustable size.

HTTP Headers Reference

Searchable reference of 70+ HTTP headers (request, response, general). Includes examples and RFC specs.

Port Number Reference

Searchable reference of 60+ common network ports (HTTP, SSH, DBs, dev servers). Category-filtered.

Chmod Calculator

Convert Unix file permissions between octal, symbolic (rwx), and chmod commands.

Cron Expression Parser

Parse a cron expression into human-readable descriptions and see the next run times.

Regex Debugger

Step-by-step breakdown of how a regex matches: capture groups, named groups, lookahead/lookbehind.

JSON Schema Validator

Validate JSON data against a JSON Schema with detailed error paths and reasons.

HTTP Request Tester

Build and send HTTP requests with custom method, headers, and body. See status, headers, and timing.

cURL → JavaScript

Convert cURL commands to fetch(), Axios, or XMLHttpRequest code.

URL Parser

Break a URL into protocol, host, path, query, and fragment with editable query parameters.

JSONPath Extractor

Query JSON documents using JSONPath expressions and inspect matching values.

Webhook Receiver

Get a unique URL to capture and inspect incoming HTTP webhooks in real time.

JavaScript Test Runner

Write and run JavaScript unit tests in your browser. Includes assert library and async support.

Cron Job Preview

Preview the next N runs of a cron expression with human-readable description and relative time.

Color Palette Generator

Generate beautiful color palettes (mono, analogous, complementary, triadic). Lock colors, copy as CSS/Tailwind.

Mock Data Generator

Generate fake data (names, emails, phones, addresses, UUIDs) for testing. JSON, CSV, SQL, TypeScript.

Crontab Generator

Visually build a cron schedule from minute/hour/day/month/weekday pickers.

.env Editor

Edit, sort, and convert .env files to JSON / YAML. Detect duplicate keys.

SQL Query Builder

Visually build SELECT queries with WHERE / ORDER BY / LIMIT clauses.

Line Diff

Compare two text blocks line-by-line and highlight added, removed, and unchanged lines.

Hex ↔ Text Converter

Convert text to hex bytes and back. Inspect individual byte values.

.gitignore Generator

Generate .gitignore files from 12 templates (Node, Python, Next.js, Go, Rust, Java, etc.).