Online Editors & Compiler
Online HTML Editor — Live Preview
Free online HTML, CSS and JavaScript editor with instant live preview and multi-file projects. Write and run web code in your browser — no signup, no install, 100% free.
Online Compiler — Python, C++, Java & 85+ Languages
Run Python, C, C++, Java, JavaScript, TypeScript, Go, Rust, PHP, Ruby and 85+ more languages instantly. Interactive stdin, real-time output, fast cloud execution — no setup, no signup.
HCODX Studio — VS Code-Style Online IDE
A VS Code-style web IDE with NPM support, JSX/TSX, live preview and zero setup. Build and ship HTML, React or Vue apps right in the browser — a fast, free CodePen alternative.
Formatters & Beautifiers
JSON Formatter & Validator
Free online JSON formatter, validator and viewer. Pretty-print, fix and inspect JSON with a tolerant parser that explains errors in context.
JavaScript Beautifier Online
Free online JavaScript beautifier — reformat minified, ugly or compressed JS with consistent indentation, spacing and braces.
CSS Beautifier Online
Free online CSS beautifier — expand minified stylesheets back into readable CSS with full control over indentation and selector spacing.
HTML Formatter Online
Free online HTML formatter and beautifier — indent and clean up raw HTML for readable, well-structured markup with preserved attributes.
Prettier Formatter Online
Run Prettier in your browser across JS, TS, JSX, CSS, HTML, JSON, Markdown and YAML with shareable presets — no install, no config.
Code Unminifier Online
Free code unminifier — turn one-line minified JavaScript, CSS or HTML back into well-indented, human-readable code in seconds.
JSON Minifier
Strip whitespace, compact JSON to one line.
JSON Validator
Validate JSON syntax with line-level errors.
YAML Formatter
Format and validate YAML configs.
XML Formatter
Pretty-print and validate XML.
JSON Pretty Print
Pretty-print JSON with adjustable indent.
JSON5 Formatter
Format and validate JSON5 (with comments and trailing commas).
JSON Beautifier
Beautify and indent JSON for readability.
JSON Prettifier
Pretty-print JSON with consistent formatting.
JSON Syntax Checker
Check JSON for syntax errors with line-by-line feedback.
JSON Lint
Lint JSON to find syntax issues.
YAML Validator
Validate YAML syntax with line-level errors.
YAML Beautifier
Beautify and indent YAML configurations.
XML Validator
Validate XML structure and well-formedness.
XML Beautifier
Beautify and indent XML documents.
SQL Formatter Online
Format SQL for Postgres, MySQL, BigQuery, SQLite, Snowflake and more. Dialect-aware indent, keyword case and tabular output in one click.
JSONPath Tester
Query any JSON with $.store.book[*].title path syntax. Live result preview, recursive descent, filter expressions, value/path/pointer output modes.
SVG Optimizer
Shrink SVG markup in your browser. Strips metadata, comments, empty groups and rounds numeric values for smaller, faster icons.
Minifiers
JavaScript Minifier Online
Free online JavaScript minifier — strip whitespace, comments and dead code to ship leaner JS with measurable size savings.
CSS Minifier Online
Free online CSS minifier with structural optimization — merge selectors, drop duplicates and collapse rules for the smallest output.
HTML Minifier Online
Free online HTML minifier — collapse whitespace, drop optional tags and inline-minify embedded CSS and JavaScript safely.
Converters
JSON to CSV / YAML / XML Converter
Convert JSON to and from CSV, YAML, XML and TOML online — structure-preserving round-trips, no upload, instant output.
Color Converter — HEX, RGB, HSL, OKLCH
Free online color converter and picker — translate between HEX, RGB, HSL, HSV and OKLCH with live previews and WCAG contrast checks.
JSON to YAML
Paste JSON, get YAML. Runs entirely in your browser.
YAML to JSON
Paste YAML, get JSON. Runs entirely in your browser.
JSON to XML
Paste JSON, get XML. Browser-only conversion.
XML to JSON
Paste XML, get JSON. No upload required.
JSON to CSV
Convert JSON arrays to CSV. Browser-only.
CSV to JSON
Paste CSV, get JSON. No upload.
JSON to TOML
Paste JSON, get TOML config.
TOML to JSON
Convert Cargo.toml or pyproject.toml to JSON.
YAML to TOML
Convert YAML configs to TOML.
TOML to YAML
Convert TOML configs to YAML.
JSON to INI
Paste JSON, get INI. Browser-only.
INI to JSON
Paste INI, get JSON. Browser-only.
JSON to Properties
Convert JSON to Java .properties format.
Properties to JSON
Convert Java .properties files to JSON.
JSON to Query String
Convert JSON to URL query string.
Query String to JSON
Parse URL query strings to JSON.
JSON to ENV
Convert JSON to .env file format.
ENV to JSON
Parse .env files to JSON.
XML to CSV
Convert XML records to CSV.
CSV to XML
Convert CSV to XML records.
XML to TOML
Paste XML, get TOML. Browser-only.
TOML to XML
Paste TOML, get XML. Browser-only.
CSV to TOML
Paste CSV, get TOML. Browser-only.
TOML to CSV
Paste TOML, get CSV. Browser-only.
YAML to INI
Paste YAML, get INI. Browser-only.
INI to YAML
Paste INI, get YAML. Browser-only.
YAML to Properties
Convert YAML to Java .properties.
Properties to YAML
Convert .properties files to YAML.
JSON5 to JSON
Strip JSON5 comments and trailing commas to plain JSON.
JSON to JSON5
Output JSON in JSON5-compatible form.
JSON to NDJSON
Convert a JSON array to newline-delimited JSON.
NDJSON to JSON
Convert newline-delimited JSON to a JSON array.
Encoders & Decoders
Base64 Encoder & Decoder
Free online base64 encoder and decoder — encode or decode text, files and images with full UTF-8 support and instant copy.
Base64 Encode
Encode text or files to base64.
Base64 Decode
Decode base64 back to text or binary.
URL Encode
Percent-encode strings for URLs.
URL Decode
Decode percent-encoded URL strings.
HTML Entity Encode
Escape HTML special characters.
HTML Entity Decode
Decode HTML entities back to characters.
Hex to Text
Decode hex bytes to UTF-8 text.
Text to Hex
Encode text as hex bytes.
JWT Decoder
Decode and inspect JWT tokens. No verification.
Binary to Decimal
Convert binary numbers to decimal.
Decimal to Binary
Convert decimal numbers to binary.
Binary to Hex
Convert binary to hexadecimal.
Hex to Binary
Convert hexadecimal to binary.
Octal to Decimal
Convert octal to decimal.
Decimal to Octal
Convert decimal to octal.
ROT13
Apply ROT13 cipher to text. Same operation encodes and decodes.
Text to Morse Code
Encode text to International Morse Code.
Morse Code to Text
Decode International Morse Code to text.
Text to ASCII
Convert each character to its decimal codepoint.
ASCII to Text
Convert decimal codepoints back to characters.
Text to Unicode Escape
Convert text to \uXXXX escape sequences.
Unicode Escape to Text
Decode \uXXXX escape sequences back to characters.
Text to Base64
Convert any text to base64-encoded form.
Base64 to Text
Decode base64-encoded data back to readable text.
Base64 Encoder
Online base64 encoder for strings and Unicode.
Base64 Decoder
Online base64 decoder for any base64 string.
URL Encoder
Percent-encode strings for safe URLs.
URL Decoder
Decode percent-encoded URLs back to readable text.
HTML Escape
Escape HTML special characters to entities.
HTML Unescape
Decode HTML entities back to characters.
JWT Parser
Parse JWT tokens to inspect headers and claims.
Caesar Cipher
ROT13 — the most common Caesar cipher.
Generators
Hash Generator — MD5, SHA-1, SHA-256, SHA-512
Free online hash generator for text and files — MD5, SHA-1, SHA-256, SHA-384 and SHA-512 powered by the native WebCrypto API.
UUID Generator
Generate UUIDv4 identifiers instantly.
Timestamp Converter
Convert between Unix timestamps and human dates.
MD5 Hash
Compute MD5 hash of any string.
SHA-256 Hash
Compute SHA-256 hash of any string.
SHA-1 Hash
Compute SHA-1 hash of any text. Native Web Crypto.
SHA-384 Hash
Compute SHA-384 hash. Native Web Crypto.
SHA-512 Hash
Compute SHA-512 hash. Native Web Crypto.
HMAC Generator
Compute HMAC signatures with a secret key.
Bcrypt Verify
Compare a plaintext password against a bcrypt hash.
ULID Generator
Generate sortable, lexicographic Universally Unique Lexicographically Sortable Identifiers.
Nano ID Generator
Generate compact URL-safe random IDs.
Password Generator
Generate strong random passwords.
Lorem Ipsum Generator
Generate Lorem Ipsum placeholder text.
Slug Generator
Convert any text into a URL-safe slug.
Fake Data Generator
Generate fake user records as JSON.
QR Code Generator
Generate QR codes from text or URLs.
Random Number Generator
Generate random numbers in a range.
GUID Generator
Generate GUIDs (Microsoft-style UUIDs).
UUID v4 Generator
Generate UUID v4 (random) identifiers.
Random ID Generator
Generate short, URL-safe random IDs.
SHA-2 Hash
Generate SHA-2 family hashes (SHA-256 default).
Checksum Generator
Generate checksums for verification (SHA-256).
Text to Slug
Convert any text into a clean URL slug.
Cron Expression Builder
Parse any cron expression to human-readable text and preview the next 10 run times. Quick presets for hourly, daily, weekly and monthly schedules.
Mermaid Live Editor
Edit Mermaid diagram source and see it rendered live. Supports flowchart, sequence, class, state, ER, gantt and pie charts. Export PNG or SVG.
JWT Generator
Sign JSON Web Tokens in your browser with HMAC-SHA256/384/512. Editable header and payload, base64-url secret support, no network calls.
JSON to Code
JSON to TypeScript
Generate TypeScript interface from JSON. Browser-only.
JSON to Go
Generate Go struct from JSON. Browser-only.
JSON to Rust
Generate Rust struct from JSON. Browser-only.
JSON to Python dataclass
Generate Python dataclass from JSON. Browser-only.
JSON to Pydantic
Generate Python Pydantic model from JSON. Browser-only.
JSON to Java
Generate Java POJO class from JSON. Browser-only.
JSON to Java record
Generate Java record from JSON. Browser-only.
JSON to Kotlin
Generate Kotlin data class from JSON. Browser-only.
JSON to C#
Generate C# class from JSON. Browser-only.
JSON to C# record
Generate C# record from JSON. Browser-only.
JSON to Swift
Generate Swift Codable struct from JSON. Browser-only.
JSON to C++
Generate C++ struct from JSON. Browser-only.
JSON to PHP
Generate PHP class from JSON. Browser-only.
JSON to Ruby
Generate Ruby class from JSON. Browser-only.
JSON to Ruby Struct
Generate Ruby Struct from JSON. Browser-only.
JSON to Dart
Generate Dart class from JSON. Browser-only.
JSON to Scala
Generate Scala case class from JSON. Browser-only.
JSON to Crystal
Generate Crystal struct from JSON. Browser-only.
JSON to Zig
Generate Zig struct from JSON. Browser-only.
JSON to Elm
Generate Elm type alias from JSON. Browser-only.
JSON to F#
Generate F# record from JSON. Browser-only.
JSON to Haskell
Generate Haskell data type from JSON. Browser-only.
JSON to Elixir
Generate Elixir struct from JSON. Browser-only.
JSON to TypeScript Interface
Generate TypeScript interfaces from JSON.
JSON to Go Struct
Generate Go structs with json tags from JSON.
JSON to TypeScript Type
Generate TypeScript types from JSON.
JSON to Go Types
Generate Go struct types from JSON.
JSON to Rust Struct
Generate Rust structs with serde derive.
JSON to Python Class
Generate Python @dataclass classes from JSON.
AI Utilities
GPT-4o Token Counter
Count tokens for OpenAI GPT-4o.
GPT-4o mini Token Counter
Count tokens for GPT-4o mini.
GPT-5 Token Counter
Count tokens for GPT-5.
OpenAI o1 Token Counter
Count tokens for OpenAI o1 reasoning model.
Claude Opus 4.7 Token Counter
Count tokens for Anthropic Claude Opus 4.7.
Claude Sonnet 4.6 Token Counter
Count tokens for Claude Sonnet 4.6.
Claude Haiku 4.5 Token Counter
Count tokens for Claude Haiku 4.5.
Gemini 2.5 Pro Token Counter
Count tokens for Google Gemini 2.5 Pro.
Llama 3.3 Token Counter
Count tokens for Meta Llama 3.3 70B.
DeepSeek V3 Token Counter
Count tokens for DeepSeek V3.
GPT-4o Cost Calculator
Calculate cost for GPT-4o API calls.
GPT-4o mini Cost Calculator
Calculate cost for GPT-4o mini.
GPT-5 Cost Calculator
Calculate cost for GPT-5 API calls.
Claude Opus 4.7 Cost Calculator
Calculate cost for Anthropic Claude Opus 4.7.
Claude Sonnet 4.6 Cost Calculator
Calculate cost for Claude Sonnet 4.6.
Claude Haiku 4.5 Cost Calculator
Calculate cost for Claude Haiku 4.5.
Gemini 2.5 Pro Cost Calculator
Calculate cost for Google Gemini API.
Llama 3.3 Cost Calculator
Calculate cost for Llama 3.3 (via Together, Groq, etc.).
DeepSeek V3 Cost Calculator
Calculate cost for DeepSeek V3 API.
LLM Cost Comparison
Compare cost for the same prompt across all major LLMs.
Prompt Token Diff
Compare two prompts to see token & cost difference.
Context Window Visualizer
See how much of each model's context window your prompt fills.
Prompt Cleaner
Strip zero-width chars, smart quotes, NBSPs from prompts.
System Prompt Extractor
Extract the system prompt from messages JSON.
Markdown Compactor
Strip excess whitespace from markdown to save tokens.
Prompt Template Variables
Render {{variables}} in prompt templates from JSON.
Function Calling Converter
Convert between OpenAI, Anthropic, and Gemini tool/function-calling formats.
Schema to Tool
Wrap a JSON Schema as an OpenAI/Anthropic/Gemini tool definition.
Text Similarity
Compare two texts using Levenshtein, Jaccard, and cosine similarity.
System Prompt Formatter
Reformat system prompts in Anthropic XML, numbered rules, or sectioned style.
OpenAI Token Counter
Approximate token count for OpenAI models.
Anthropic Token Counter
Approximate Claude token count.
LLM Token Counter
Token count comparison across all major LLMs.
AI Cost Calculator
Compare AI API costs across all major LLMs.
GPT Cost Calculator
Estimate OpenAI GPT API call costs.
Claude Cost Calculator
Estimate Anthropic Claude API costs.
Diff & Compare
Text Tools
Case Converter
Convert text between 11 different cases.
Word Counter
Count words, characters, sentences, and paragraphs.
Character Counter
Count characters with social media limits.
Line Counter
Count total, non-empty, and empty lines.
Reverse Text
Reverse text character by character.
Sort Lines
Sort lines of text alphabetically.
Deduplicate Lines
Remove duplicate lines from text.
Trim Whitespace
Strip extra whitespace from text.
Find and Replace
Replace text within a document.
Text Cleaner
Strip hidden chars and normalize whitespace.
Regex Tester
Test regular expressions against any text in the browser. Live highlight, capture-group table, all six flags, replace mode with $1..$9 backrefs.
CSS Generators
CSS Gradient Generator
Generate CSS gradients with live preview.
Box Shadow Generator
Build CSS box-shadow with live preview.
Border Radius Generator
Generate CSS border-radius with per-corner control.
Text Shadow Generator
Build CSS text-shadow with live preview.
CSS clamp() Generator
Build responsive CSS clamp() values.
CSS Specificity Calculator
Calculate CSS specificity for any selector. Live breakdown of inline, ID, class and type counts plus which rule wins. Handles :is, :not, :where, :has.
Markdown
Color Tools
HEX to RGB
Convert HEX color codes to RGB.
RGB to HEX
Convert RGB color values to HEX.
HSL to HEX
Convert HSL colors to HEX.
Color Picker
Pick colors and see all formats at once.
WCAG Contrast Checker
Check WCAG 2.1 contrast ratio between two colors. Live AA / AAA pass/fail for normal and large text with a sample preview on real colors.
Network & IP
CIDR Calculator
Calculate network, broadcast, and host ranges from CIDR notation.
IP ↔ Integer
Convert IPv4 addresses to integers and back.
IPv4 to IPv6
Convert IPv4 addresses to IPv6 mapped notation.
MAC Address Generator
Generate random MAC addresses.
Subnet Calculator
Calculate IPv4 subnet ranges from CIDR.
IP Converter
Convert IPv4 addresses between decimal, hex, and binary.
Utilities
Code Diff Checker Online
Free online code diff checker — compare two snippets side-by-side with line-level highlights, word diffs and copy-ready output.
.htaccess Generator Online
Free online .htaccess generator — build Apache rules visually for redirects, rewrites, headers, caching and access controls.
Image to Base64
Convert images to base64 data URIs.
Favicon Generator
Create favicons from text or letters.
Emoji Picker
Find and copy emojis with codepoints.
HTTP Status Codes
Look up any HTTP status code with its name, category and use case. Searchable table covering RFC 9110 plus WebDAV, 425 and 451.
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