Free Online Developer Tools

Paste Anything — Smart Detector

Paste any text and instantly detect its format — JSON, JWT, Base64, UUID, SQL, timestamps, colors, and more.

Tool Pipeline Builder

Chain tools together — output of one step feeds into the next. Deep-link sharing.

Bulk / Batch Processor

Process multiple items at once — generate bulk UUIDs, hash lists of strings, Base64 encode batches, and more.

JSON Formatter & Beautifier

Format and beautify JSON data with syntax highlighting and tree view.

JSON Validator

Validate JSON syntax with detailed error messages.

JSON to CSV Converter

Convert between JSON arrays and CSV format with custom delimiters.

JSON to TypeScript Generator

Generate TypeScript interfaces and types from JSON data instantly.

JSON to Python Converter

Convert JSON to Python dataclasses, Pydantic models, or TypedDict with automatic type inference.

JSON Flatten & Unflatten

Flatten nested JSON to dot-notation keys or unflatten flat keys back to nested JSON.

jq Playground — JSON Processor

Test jq queries interactively in your browser. Filter, transform, and explore JSON with real-time results.

JSON Mock Data Generator

Generate realistic fake JSON data from a template. Smart field detection turns key names into realistic values.

JSON Schema Validator

Validate JSON data against a JSON Schema with detailed error messages and path reporting.

JSONPath Evaluator

Test JSONPath expressions against JSON data in real time. Supports filters, wildcards, recursive descent, and array slicing.

JSON Schema Generator

Generate JSON Schema from sample JSON data. Infers types, detects formats, supports Draft 2020-12, Draft-07, and Draft-04.

JSON Patch / Diff Generator

Generate RFC 6902 JSON Patch operations by diffing two JSON objects, or apply a patch to a document.

Base64 Encoder / Decoder

Encode and decode Base64 strings instantly.

URL Encoder / Decoder

Encode and decode URL components safely.

Hash Generator (MD5/SHA)

Generate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes.

JWT Decoder

Decode and inspect JSON Web Token header, payload, and claims.

HTML Entity Encoder / Decoder

Encode special characters to HTML entities or decode them back.

Image to Base64 Converter

Convert images to Base64 encoded strings. Output as Data URI, CSS, HTML, or raw Base64.

String Escape / Unescape Tool

Escape and unescape strings for JSON, JavaScript, HTML, XML, URL, CSV, SQL, and regex.

ASCII / Binary / Hex Converter

Convert text between ASCII, binary, hexadecimal, octal, and decimal representations instantly.

Protobuf Decoder — Wire Format Viewer

Decode Protocol Buffer binary data without a .proto file. View field numbers, wire types, and values from Base64 or hex input.

Encoding Detective — Mojibake Repair

Detect and repair encoding issues (mojibake) in text. Fixes UTF-8 read as Latin-1, double-encoded UTF-8, and garbled characters.

HTML Beautifier

Format and indent HTML code for readability.

XML Formatter & Validator

Format, beautify, and validate XML data with indentation options.

SQL Formatter & Beautifier

Format SQL queries with keyword casing and indentation options.

CSS Minifier & Beautifier

Minify CSS to reduce file size or beautify for readability.

JavaScript Minifier & Beautifier

Minify JavaScript to reduce file size or beautify for readability.

TOML Formatter & Converter

Format, minify, and convert TOML data with bidirectional JSON conversion.

YAML Formatter, Validator & Minifier

Format, validate, and minify YAML data online with configurable indentation and instant error detection.

UUID Generator

Generate random UUID v4 and v7 identifiers instantly.

Password Generator

Generate strong, random passwords with customizable options.

QR Code Generator

Generate QR codes from text or URLs with custom colors.

Lorem Ipsum Generator

Generate placeholder text by paragraphs, sentences, or words.

Cron Expression Generator

Build, parse, and validate cron expressions with a visual editor.

chmod Calculator

Calculate Unix file permissions with an interactive chmod calculator.

Slug / URL Generator

Generate URL-safe slugs from any text. Convert titles to clean, SEO-friendly URLs.

.gitignore Generator

Generate .gitignore files for any project. Select languages, frameworks, and IDEs to create a comprehensive .gitignore.

Regex Tester

Test and debug regular expressions with real-time matching.

Regex Explainer — Plain English

Paste any regular expression and get a plain English explanation of what each part does.

HMAC Generator

Generate HMAC-SHA256, HMAC-SHA384, HMAC-SHA512, and HMAC-SHA1 keyed-hash signatures.

Content Security Policy Generator

Generate Content Security Policy headers with an interactive builder. Configure all CSP directives with presets and custom domains.

SSH Key Generator

Generate RSA and ECDSA SSH key pairs entirely in your browser. Private keys never leave your device.

SSL Certificate Decoder

Decode PEM-encoded SSL/TLS certificates and view subject, issuer, validity dates, SANs, and key information.

CORS Header Builder & Generator

Generate CORS headers interactively. Output as HTTP headers, Nginx config, Express middleware, or Apache .htaccess.

Color Picker & Converter

Pick colors and convert between HEX, RGB, and HSL formats.

Placeholder Image Generator

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

SVG Path Editor & Visualizer

Edit, visualize, and understand SVG path commands. Live preview with command breakdown, control points, and formatting.

Diff Checker / Text Compare

Compare two texts side by side and see differences highlighted.

.env Diff & Merge

Compare .env files side by side. Find missing keys, detect changes, and generate merged environment files.

JSON-YAML Converter

Convert between JSON and YAML formats instantly.

Epoch / Unix Timestamp Converter

Convert Unix timestamps to dates and vice versa.

Markdown to HTML Preview

Convert Markdown to HTML in real time with a live preview.

Curl to Fetch/Axios Converter

Convert curl commands to JavaScript fetch, Axios, or Node.js code instantly.

Tailwind CSS Converter

Convert Tailwind CSS utility classes to plain CSS and vice versa. Supports spacing, colors, typography, flexbox, grid, and more.

OpenAPI to TypeScript

Generate TypeScript interfaces and types from OpenAPI 3.x or Swagger 2.0 JSON specs. Supports $ref, enums, and allOf/oneOf.

Text Case Converter

Convert text between camelCase, snake_case, PascalCase, kebab-case, SCREAMING_SNAKE_CASE, Title Case, and more.

Number Base Converter

Convert numbers between binary, octal, decimal, and hexadecimal with arbitrary precision.

CSV Viewer & Editor

View, sort, search, and filter CSV data in an interactive table. Supports CSV, TSV, and custom delimiters.

Date & Time Format Converter

Convert dates between ISO 8601, RFC 2822, Unix timestamps, and human-readable formats with timezone support.

SQL to MongoDB & N1QL Converter

Convert SQL queries to MongoDB find/aggregate syntax and Couchbase N1QL. Supports SELECT, INSERT, UPDATE, DELETE with WHERE, GROUP BY, and JOINs.

Semver Calculator & Comparator

Parse, compare, bump, and sort semantic versions. Supports pre-release labels, build metadata, and bulk sorting.

Byte / Size Calculator

Calculate string byte length in UTF-8/UTF-16/ASCII. Convert between bytes, KB, MB, GB, TB with SI and IEC units.

URL Parser & Builder

Parse URLs into components (protocol, hostname, path, query parameters, hash) or build URLs from parts.

Glob to Regex Converter

Convert glob patterns to regular expressions and vice versa. Test against strings with explanations.

Math Expression Evaluator

Evaluate math expressions safely. Supports hex, binary, octal, functions (sqrt, log, sin), and multiple output formats.

SQL DDL to TypeScript Converter

Convert SQL CREATE TABLE statements to TypeScript interfaces. Maps SQL types to TS types, handles nullable columns and arrays.

Duration / Time Calculator

Convert between milliseconds, human-readable durations, ISO 8601, and HH:MM:SS. Calculate time breakdowns for timeouts and TTLs.

CSS Unit Converter — px, rem, em, pt, vw, vh

Convert between CSS units instantly. px to rem, em to px, pt to px, and more with configurable base font size.

JSON to Go Struct Converter

Convert JSON data to Go struct definitions instantly. Generates typed structs with json tags and proper Go naming.

HTML to Markdown Converter

Convert HTML to clean Markdown instantly. Handles headings, links, images, tables, lists, and code blocks.

CSV to SQL Converter

Convert CSV data to SQL CREATE TABLE and INSERT statements. Auto-detects column types with configurable options.

SQL to ORM Converter

Convert SQL CREATE TABLE statements to ORM model code for Prisma, Sequelize, TypeORM, SQLAlchemy, and Django.

HTTP Status Code Explorer

Look up any HTTP status code instantly. Searchable reference with descriptions and use cases.

Git Command Builder

Find the right git command for any situation. Interactive wizard with 30+ common scenarios.

GraphQL Schema Explorer

Paste a GraphQL schema and explore types, fields, relationships, and auto-generated sample queries.

MIME Type Lookup

Look up MIME types by file extension or find extensions for a MIME type. Shows compressibility, charset, and binary/text classification.

Word & Character Counter

Count words, characters, sentences, and paragraphs instantly. See reading time, speaking time, and top word frequency.

Text Line Sorter, Deduplicator & Tools

Sort, deduplicate, reverse, number, and trim text lines online. Remove empty lines and filter duplicates instantly.

Subnet / CIDR Calculator

Calculate subnet details from any IP address and CIDR prefix. View network, broadcast, host range, and masks.

Nginx Config Generator

Generate Nginx configurations for reverse proxy, static sites, SPAs, load balancing, and more with SSL, gzip, and security headers.

Docker Compose Validator

Validate docker-compose.yml files for YAML syntax, schema errors, and best practices.

Robots.txt Generator & Validator

Generate and validate robots.txt files. Block AI crawlers, configure search engine access, and test URL rules.

GitHub Actions YAML Validator

Validate GitHub Actions workflow YAML files. Checks triggers, jobs, steps, runs-on, and catches common mistakes.