deftools.io 🔧 Developer Tools

🔧 Developer Tools

Utilities for software development workflows — encoding and decoding (Base64, URL), code formatters and beautifiers (HTML, CSS, JavaScript, SQL), diff viewers, regular expression testers, and code snippet generators. These tools help you write, format, debug, and ship code faster without leaving the browser.

.env File Editor
Edit and validate .env files — detect duplicate keys, empty values, and unsafe characters
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🌳 AST Explorer
Parse code in 10+ languages and explore the syntax tree. Select nodes, see their properties.
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🌳 JSON Tree Explorer
Interactive JSON tree explorer for inspecting large payloads — collapse branches, search nodes, copy JSONPath. A focused tree-first inspection tool, distinct from a full JSON formatter/validator.
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🏗️ Terraform Plan Visualizer
Visualize terraform plan JSON output — resource change tree with create/update/destroy/replace badges and attribute diff
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🐳 Docker Image Inspector
Inspect Docker images from a docker save tar — layers, sizes, files per layer, and wasted space analysis.
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🐳 Docker Run to Compose
Convert a docker run command to a docker-compose.yml file. Paste any docker run flags and get the equivalent compose service.
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📊 CSV Analytics Lab
Upload CSV files and query them with SQL. Run aggregations, JOINs, window functions — all in your browser.
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📝 Markdown Preview
Live Markdown preview with GitHub-style rendering. Type on the left, see the result on the right.
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📝 Markdown to HTML Converter
Convert Markdown to clean HTML. GitHub Flavored Markdown with tables, task lists, and code highlighting.
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📡 HAR Viewer
View HTTP Archive (HAR) files: waterfall chart, request details, headers, timings, and filters.
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📦 Data URI Generator
Convert text to data URI for inline embedding in HTML, CSS, and JavaScript
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📧 EML Viewer
View .eml email files online — headers, HTML/text body, and attachments. No upload needed.
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🔀 Byte Converter
Convert data sizes between bytes, KB, KiB, MB, MiB, GB, GiB, TB, bits and more. Decimal (SI) and binary (IEC) units, plus a download-time estimator.
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🔌 Protobuf Decoder
Decode Protocol Buffers binary data (hex or base64) to JSON without a .proto file
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🔍 Query Plan Visualizer
Interactive EXPLAIN plan visualizer for PostgreSQL, MySQL, and SQLite — tree view, cost hotspots, and node analysis
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🔍 XPath Tester
Test XPath expressions against XML and see matching nodes highlighted with counts and previews
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🔎 Hexdump Viewer
View text or binary as a hexdump (xxd format). Shows offset, hex bytes, and ASCII side panel side by side.
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🔐 Base64 Encode/Decode
Encode text to Base64 or decode Base64 back to text. Unicode-safe, URL-safe mode, file support.
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🔐 HTTP Basic Auth Generator
Generate and decode HTTP Basic Authentication headers — convert username:password to and from the Authorization: Basic header.
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🔢 Base32 Encode/Decode
Encode text to Base32 or decode Base32 back to text. Supports RFC 4648 standard and extended hex alphabets.
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🔢 LLM Token Counter
Count tokens for GPT-4o, GPT-4, Claude, Gemini, Llama and Mistral
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🔢 Multi-Format ID Generator
Generate NanoID, ULID, CUID2, KSUID, and UUID v4/v7 identifiers. Decode Snowflake IDs from Twitter/X and Discord back to timestamps and metadata. The go-to tool when you need IDs beyond plain UUIDs.
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🔤 Font Subsetter
Subset TTF, OTF, or WOFF2 fonts — keep only the character ranges you need and reduce font file size by up to 90%
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🔧 .env Converter
Convert .env files to JSON, YAML, Docker Compose, shell export, or systemd — and convert JSON back to .env.
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🖼️ Code Screenshot Generator
Create beautiful code screenshots with syntax highlighting, themes, window chrome, and export to PNG
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🗄️ CSV to SQL INSERT
Convert CSV data into SQL INSERT statements. Pick a table name, choose MySQL, PostgreSQL, SQLite or SQL Server quoting, and export seed scripts.
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🗄️ SQL Data Workbench
Run SQL queries on CSV, Parquet, and JSON files with JOINs between datasets
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🗄️ SQLite Viewer
Open SQLite database files in your browser: browse tables, preview data, and run SQL queries.
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🗜️ Brotli Compressor
Brotli compress and decompress text online — up to 26% smaller than gzip, served by CDNs with quality 0–11 control and Base64 output
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🗜️ Compression Tester
Compare Brotli, Gzip, and Deflate compression side-by-side — see sizes, ratios, and speeds for your data in one view
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🗜️ Gzip Compressor
Gzip compress and decompress text online — the universal HTTP Content-Encoding format for .gz files, API payloads, and web server compression
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🤖 AI Crawler Blocker
Generate robots.txt rules to block AI crawlers like GPTBot, ClaudeBot and CCBot from scraping your site.
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🤖 AI Model Comparison
Compare AI model pricing, context windows, and capabilities side-by-side — with a cost calculator for input and output tokens
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🤖 AI Prompt Builder
Build and format AI prompts with variables, templates, and API-specific output for OpenAI, Anthropic, and Google Gemini
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🤖 llms.txt Generator
Generate an llms.txt file for your website to guide AI assistants and LLMs. Form-based builder with live markdown preview.
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🤖 MCP Config Generator
Generate MCP server configuration JSON for Claude Desktop, Claude Code, and other MCP clients. Form-based builder with validation.
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🦜 Parquet Viewer
View Apache Parquet files in your browser: schema, column statistics, and data preview.
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🧬 JSON Graph Visualizer
Visualize JSON data as an interactive node graph with zoom, drag, and collapsible branches
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🧲 Torrent Decoder
Decode .torrent files — view file list with sizes, trackers, infohash, and creation date.
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🛡️ README Badge Generator
Build shields.io badges for your README — pick a style, label, message, and colors to get instant markdown or HTML.
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ASCII Table
Searchable ASCII table with decimal, hex, octal, binary, and HTML entity codes for all 128 characters.
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Bitwise Calculator
Bitwise AND, OR, XOR, NOT, shifts on 32-bit integers. Visual bit grid, click to toggle bits, results in decimal, hex, binary and octal.
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chmod Calculator
Compute Unix file permissions: toggle read/write/execute for user, group, others. Get numeric, symbolic, and full chmod commands.
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Cipher Playground
Encode & decode classic ciphers: Caesar, ROT13, Atbash, Vigenère, A1Z26, Morse, Binary, Hex, Rail Fence, Bacon. Live preview, deep-link, copy, history.
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Code Complexity Analyzer
Analyze cyclomatic and cognitive complexity of JavaScript and TypeScript code. Per-function metrics with maintainability index.
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Commit Message Builder
Build clean Conventional Commits messages with live preview, scope, breaking-change flags, footers, and gitmoji. Copy-ready output, deep-link share, and recent history.
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Cookie Parser & Inspector
Parse Set-Cookie or Cookie headers into name, value, attributes and warnings, or build a Set-Cookie header from a form.
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Cron Expression Explainer
Parse any cron expression into a human-readable schedule and preview upcoming run times.
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CSS Minifier
Minify and beautify CSS instantly. Strip comments, whitespace, and redundant semicolons — or pretty-print minified CSS back to readable format.
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CSS Selector Tester
Test CSS selectors against HTML and see matched elements with counts, tags, and snippets. Supports :nth-child, attribute selectors, combinators, and pseudo-classes.
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CSS Specificity Comparator
Compare two CSS selectors side by side — see ID, class, and element scores with visual bars, and learn which rule wins when both apply.
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Curl → Code
Convert curl commands to Python, JavaScript, Go, and Rust code.
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Diff Checker
Compare two pieces of text line by line with word-level highlighting
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Email HTML Linter
Lint your email HTML against Can I Email data — catch Outlook, Gmail, and Apple Mail rendering issues before you send.
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Email Validator
Validate email addresses, detect typos, disposable and role-based addresses, and normalize Gmail plus-addressing and dots.
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Float Inspector (IEEE 754)
Inspect IEEE 754 floating-point numbers: sign, exponent, mantissa bits, exact decimal value, next/previous float. Single (32-bit) and double (64-bit) precision.
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GitHub Actions Validator
Validate GitHub Actions workflow YAML — syntax, required fields, deprecated actions, job dependencies, and context expressions
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Glob Pattern Tester
Test glob patterns against a list of file paths. Supports *, **, ?, brace expansion, and negation (!).
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GraphQL Client
Query any GraphQL API — write a query, add variables and headers, send the request, and view the JSON response with export to cURL or fetch
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GraphQL Formatter
Format and beautify GraphQL queries, mutations, fragments, and schemas with proper indentation and line breaks.
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Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-384, SHA-512 hashes from text or files. Hex, Base64, or Base64URL output. Verify a hash against input.
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HTML Entity Encoder
Encode and decode HTML entities. Convert special characters to named, decimal, or hex references and back.
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HTML Formatter
Beautify and indent HTML for readability — turn messy or minified markup into clean, properly nested code with 2-space or 4-space indentation.
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HTML Playground
Live HTML/CSS/JS sandbox. Write code in three panes, see instant preview in a sandboxed iframe, capture console output, share via deep-link.
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HTML Table Generator
Build HTML tables visually. Add rows and columns, set headers, and copy the markup.
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HTML to JSX Converter
Convert HTML to React JSX. Transforms class to className, inline styles to objects, event handlers, comments, and self-closing tags.
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HTML to Markdown
Convert HTML to clean Markdown. Paste any HTML snippet — headings, links, images, lists, tables, code — and get Markdown output instantly.
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HTTP Method Reference
Quick reference for all HTTP methods. Learn what each method does, when to use it, and see code examples.
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HTTP Request Builder
Build an HTTP request and convert it to curl, fetch, axios, Python requests, Go, and raw HTTP text
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HTTP Status Codes
Searchable reference for all HTTP status codes (1xx–5xx). Filter by category, copy responses, see usage examples.
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JS Minifier
Minify and beautify JavaScript online. Remove comments, whitespace, and dead code — or pretty-print minified JS back to readable form.
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JSON → Go Struct
Generate Go structs from JSON. Paste JSON, get type definitions with json tags, omitempty, embedded structs, and pointer nullables.
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JSON → GraphQL Schema
Convert JSON to GraphQL types. Paste a JSON object and get GraphQL schema type definitions with nullable/non-nullable fields.
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JSON → Pydantic Model
Generate Pydantic v2 BaseModel classes from JSON with type hints, Optional fields, and snake_case alias support. Paste JSON, get Python model definitions for FastAPI and data validation.
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JSON → TypeScript
Generate TypeScript interfaces from JSON — optional properties, union types, readonly fields, and nested objects. Paste JSON, get ready-to-use .d.ts definitions.
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JSON → Zod Schema
Generate Zod validation schemas from JSON — z.object(), z.string(), z.number(), z.enum(), z.array() with nullable support. Paste JSON, get runtime type-safe validation code.
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JSON ↔ XML Converter
Convert JSON to XML and XML to JSON online. Supports attributes, arrays, namespaces, and custom root elements.
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JSON Diff
Compare two JSON objects semantically. Shows added, removed, changed, and type-changed keys with full dot-path notation. Handles nested objects and arrays.
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JSON Flatten / Unflatten
Flatten nested JSON to dot-notation key-value pairs and unflatten them back
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JSON Formatter & Validator
Format, validate, and minify JSON with real-time syntax checking. Beautify messy payloads, compress for production, catch errors before they break your app, and share via deep-link.
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JSON Key Sorter
Sort JSON object keys alphabetically or in a custom order. Deep recursive sort for stable snapshots before diffing or committing.
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JSON Schema Generator
Infer a JSON Schema (Draft 2020-12) from any sample JSON. Live, configurable schema generation with format detection.
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JWT Decoder & Debugger
Decode and inspect JSON Web Tokens — view header, payload, and signature claims. Verify HS256/384/512, RS256, ES256 signatures and check token expiration.
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Key Code Inspector
Press any key to inspect its event properties — key, code, keyCode, location, modifiers, and friendly hotkey combo. Live modifier indicators, press history, copy-ready listener snippet, and a reference table of common key codes. Essential for building keyboard shortcuts, games, and accessible UIs.
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Log File Viewer
Paste logs and instantly filter, search, and analyze them with severity detection and statistics
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Mailto Link Generator
Generate mailto: links with to, cc, bcc, subject and body fields. URL-encoded and ready to use in HTML and email templates.
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MIME Type Lookup
Searchable database of MIME types and file extensions. Reverse lookup (extension → MIME), forward lookup (MIME → extensions), category filters, common-type cheatsheet, and copy helpers.
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Morse Code Converter
Encode text to Morse code, decode Morse back to text, and playback audio. Supports international Morse code standard.
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NDJSON ↔ JSON Converter
Convert JSON array to NDJSON (JSON Lines) and back. Split JSON arrays into newline-delimited records, or merge JSONL into a single JSON array.
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Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal with arbitrary precision. BigInt-powered exact conversion for 256-bit values and UUIDs.
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Number Stats
Paste a list of numbers and get instant descriptive statistics: count, sum, mean, median, mode, range, variance, standard deviation, quartiles, IQR, outliers, skewness, kurtosis, and a live histogram.
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Open Source License Chooser
Answer 3 questions to find the right open-source license for your project — MIT, Apache 2.0, GPL 3.0, or BSD.
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OpenAPI Client Generator
Generate a typed TypeScript API client from an OpenAPI/Swagger spec — fetch or axios with interfaces for every endpoint
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OpenAPI Diff
Compare two OpenAPI specs and see a breaking-changes report: removed endpoints, changed types, new required params, and more.
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package.json Generator
Visually build a package.json file — choose presets for Node, React, Next.js, and more, configure every field, and get live JSON output
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Playwright Snippet Generator
Generate Playwright code snippets for common browser automation tasks. Supports selectors, actions, assertions, and more.
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Regex Explainer
Decode any regex into plain English — paste a pattern and see every token explained: anchors, quantifiers, character classes, groups. Understand what a regex matches without running it.
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Regex Tester
Test and debug regular expressions against sample text — live match highlighting, capture group inspection, replace mode, common pattern library.
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SCSS to CSS Compiler
Compile SCSS and Sass to CSS online — live preview with nesting, variables, mixins, and source map support
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SemVer Calculator
Parse, validate, and compare semantic versions (semver). Bump major/minor/patch, test range constraints (^ ~ > x-range), diff versions, and inspect pre-release precedence.
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Slug Generator
Convert titles to clean URL slugs. Unicode-aware, multi-line batch mode, custom separators.
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Snowflake ID Decoder
Decode Discord, Twitter/X, and Instagram snowflake IDs to timestamps, worker IDs, and sequence numbers. Also generate ID ranges from timestamps.
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SQL Formatter
Format, beautify, and minify SQL queries. Dialect-aware keyword handling for MySQL, PostgreSQL, SQLite, and Standard SQL.
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SQL Schema Diff
Compare two sets of CREATE TABLE statements and generate ALTER TABLE migration scripts: added/removed columns, changed types, and new/dropped indexes.
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String Escape / Unescape
Escape and unescape text for HTML, URL, JSON, Regex, Base64, and C-string. Live preview, bulk mode, one-click copy.
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SVG to JSX Converter
Convert SVG markup to React JSX component. Transforms class to className, kebab-case attributes to camelCase, inline styles to objects.
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Timestamp Converter
Convert Unix timestamps to human-readable dates and back. ISO 8601, RFC 2822, Excel serial, local time, relative time.
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tsconfig.json Builder
Visually build a tsconfig.json file — choose presets for Node, React, and Next.js, configure every option with explanations, and get live JSON output
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Unicode Inspector
Inspect every character's codepoint, UTF-8/UTF-16 bytes, HTML/JS/CSS/URL escapes, and block. Detects invisible, combining, control, and zero-width characters.
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URL Encoder / Decoder
Encode and decode URLs, URI components, and query strings. Supports encodeURIComponent, encodeURI, and base64.
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URL Parser
Parse any URL into its components: protocol, host, path, query params, hash. Edit fields and rebuild a URL, or share a parsed URL via deep-link.
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UUID Generator & Inspector
Generate UUID v4 and v7 identifiers in bulk — random and time-ordered. Inspect any UUID to extract its embedded creation timestamp and version details. Also generates GUIDs for Microsoft conventions.
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WebSocket Tester
Test WebSocket connections, send messages, and view real-time responses. Supports multiple echo servers and custom endpoints.
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XML Formatter
Format, validate, minify and convert XML. Syntax highlight, XML to JSON, stats, and tree view.
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YAML ↔ JSON
Convert between YAML and JSON formats. Real-time conversion.
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