Free Online Developer Tools

Encode text or files to Base64 or decode Base64 back online for free. Instant conversion, no signup, runs in your browser.

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Format and validate JSON online for free. Beautify with indentation, validate syntax, or minify. Runs in your browser, no signup.

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Convert CSV to JSON or JSON to CSV online for free. Live preview as you type or upload a file. No signup, runs in browser.

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Convert Unix timestamps to dates and dates to timestamps online for free. Supports seconds, milliseconds, ISO 8601. No signup.

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Decode JWT tokens online for free. Inspect header, payload, and claims. Verify expiration and signature algorithm. No signup, runs in browser.

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Test regular expressions online for free with live match highlighting, capture groups, and flag toggles. Supports JavaScript regex. No signup.

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Encode or decode URLs and query strings online for free. Supports encodeURI and encodeURIComponent modes. No signup.

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Compare two texts online for free and see additions, removals, and changes highlighted line by line. Like a code diff tool. No signup.

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Convert JSON to YAML or YAML to JSON online for free. Live validation as you type. No signup, runs in browser.

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Convert HTML to clean Markdown online for free. Paste HTML, get Markdown instantly. Perfect for migrating content. No signup.

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Convert numbers between binary, octal, decimal, and hexadecimal online for free. Real-time conversion as you type. No signup.

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Calculate your exact age in years, months, days, hours, and minutes from your date of birth. Free, instant, no signup.

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Format and validate XML online for free. Beautify with indentation, check for errors, or minify. Syntax highlighting included. No signup.

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Format and beautify SQL queries online for free. Proper indentation, keyword uppercasing, and clean output. No signup.

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Paste a cron expression and see when it runs in plain English online for free. Shows next 10 execution times. No signup.

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Convert between metric and imperial units online for free. Length, weight, temperature, speed, area, volume, and data. No signup.

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Generate HTML meta tags for SEO, Open Graph, and Twitter Cards online for free. Live preview of how your page appears in Google and social media. No signup.

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Generate a robots.txt file online for free. Set allow/disallow rules, sitemap URL, and crawl delay. Download or copy. No signup.

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Minify HTML code online for free. Remove comments, whitespace, and unnecessary attributes. Reduce file size for faster page loads. No signup.

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Minify CSS online for free. Remove comments, whitespace, and redundant code. Smaller stylesheets for faster websites. No signup.

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Minify JavaScript code online for free using Terser. Removes whitespace, shortens variable names, eliminates dead code. No signup.

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Convert Markdown to clean HTML online for free. Live preview with one-click download. Perfect for blog posts and documentation. No signup.

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Calculate Linux file permissions visually online for free. Toggle read, write, execute for owner, group, others. See chmod 777, 755, 644, etc. No signup.

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Build cron expressions with a visual editor online for free. Select minute, hour, day, month, weekday. Get the cron string instantly. No signup.

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Find your public IP address and look up any IP for geolocation, ISP, timezone, and more. Free, no signup.

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Look up DNS records for any domain online for free. Check A, AAAA, CNAME, MX, TXT, NS, and SOA records. No signup.

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Merge two texts side by side online for free. Pick changes from either version and resolve conflicts visually. No signup.

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Scan and read QR codes from images online for free. Upload a screenshot or photo, instantly decode URLs, text, Wi-Fi, and vCards. No signup.

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Generate a JSON Schema from sample JSON online for free. Auto-infers types, required fields, and nested structures. No signup.

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Encode special characters to HTML entities or decode them back online for free. Named, numeric, and hex entities supported. No signup.

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Build Markdown tables visually online for free. Add rows and columns, type content, copy the formatted table. Perfect for GitHub READMEs. No signup.

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Convert JSON arrays to CSV format online for free. Handles nested objects, custom delimiters, and downloads as .csv file. No signup required.

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Convert text to binary, hexadecimal, decimal, and octal online for free. Also convert binary back to text. Supports ASCII and UTF-8.

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Generate valid test credit card numbers for Stripe, PayPal, Braintree, and other payment gateways. Visa, Mastercard, Amex — all Luhn-valid. No real charges.

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Preview how your Open Graph meta tags look on Twitter, Facebook, LinkedIn, and Discord. Edit title, description, and image — see live previews instantly.

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Validate and format YAML online for free. Detect syntax errors, auto-indent, and convert between YAML and JSON. No signup required.

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Generate JSON Web Tokens (JWT) online for free. Set payload, expiry, and algorithm — sign with a secret key. For testing and development.

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Generate htpasswd password hashes online for free. Supports bcrypt, MD5, and SHA-1 algorithms. Perfect for Apache .htaccess authentication.

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Validate .env files online for free. Detect syntax errors, duplicate keys, empty values, and missing quotes. Compare against .env.example.

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Compare two blocks of text and find differences online for free. Highlights additions, deletions, and changes line by line. No signup.

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Convert between CSS units online for free. PX to REM, EM to PX, PT to PX, and more. Set your base font size for accurate conversions.

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Parse and break down any URL into its components online for free. See protocol, host, path, query parameters, hash, and more.

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Build regular expressions with a visual helper online for free. Common patterns for emails, URLs, phones, dates, and more. Test instantly.

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Find JSONPath expressions by clicking on values in your JSON data. Paste JSON, click any value, and get the exact path. Copy paths instantly.

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Generate .gitignore files online for free. Select your languages, frameworks, and IDEs to create a comprehensive gitignore file. Copy or download instantly.

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Build UTM-tagged URLs for campaign tracking online for free. Enter source, medium, campaign, term, and content parameters. Copy the tagged URL instantly.

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Convert XML to JSON and JSON to XML online for free. Paste your XML data and get formatted JSON output instantly. Handles nested elements and attributes.

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Detect your screen resolution, viewport size, device pixel ratio, color depth, and more online for free. See all your display information at a glance.

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Convert pixels to density-independent pixels (DP/DIP) and scale-independent pixels (SP) for Android development. Supports all screen densities (mdpi, hdpi, xhdpi, xxhdpi, xxxhdpi).

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Complete regular expression cheatsheet and reference guide. Quick lookup for regex syntax, character classes, quantifiers, anchors, groups, lookaheads, and common patterns.

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Complete HTTP status codes reference with explanations, categories, and use cases. Searchable list of all 1xx, 2xx, 3xx, 4xx, and 5xx status codes.

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Calculate IP subnets online for free. Enter an IP address and CIDR notation to get network address, broadcast address, usable host range, subnet mask, and more.

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Convert text between developer naming conventions online for free. camelCase, snake_case, PascalCase, kebab-case, CONSTANT_CASE, dot.case, and more.

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Compare two JSON objects online for free. See added, removed, and changed keys highlighted with a clear visual diff. Paste and compare instantly.

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Convert SVG code to a CSS background-image data URI online for free. Paste your SVG and get optimized CSS ready to use. No external files needed.

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