35 Developer Tools for Website Owners

Every website owner faces the same problem: countless small tasks that individually take minutes but collectively consume hours. Encoding a URL. Generating a UUID. Checking if your favicon works. Testing a regex pattern. These aren't hard problems, but they're friction that slows you down.

I built RJL.io to solve this - 35 free, browser-based developer tools that handle the tedious stuff so you can focus on building. No accounts. No subscriptions. No data leaving your browser. Just tools that work.

SEO & Site Health Tools

Your site's search performance depends on dozens of small details. These tools help you get them right.

SEO Analyzer

Enter any URL and get a comprehensive SEO audit: title tag length, meta description, heading structure, image alt texts, mobile friendliness, page speed indicators, and more. Catch the issues Google penalizes before they hurt your rankings. Unlike expensive SEO suites, this gives you the essentials for free.

Meta Tag Generator

Generate all the meta tags your pages need: Open Graph for Facebook, Twitter Cards, standard SEO tags, and JSON-LD structured data. Fill in a form, copy the output, paste into your HTML. Perfect for ensuring every page has proper social sharing previews and search engine metadata.

robots.txt Generator

The robots.txt file controls what search engines can crawl - get it wrong and you could deindex your entire site. This tool generates properly formatted robots.txt files with sitemap references, crawl-delay settings, and specific allow/disallow rules. One less thing to mess up.

Favicon Checker

Favicons are surprisingly complex in 2026 - you need different sizes for browsers, iOS, Android, and Windows tiles. This tool checks your site for all required favicon formats and shows you what's missing. No more broken icons on bookmarks or home screens.

Favicon Generator

Upload one image and generate all the favicon sizes you need: ICO, PNG in multiple sizes, Apple Touch icons, Android icons, and the manifest.json configuration. Download a ZIP with everything ready to deploy.

Code & Text Utilities

The bread and butter of daily development - transforming, encoding, and validating text.

Base64 Encoder/Decoder

Encode text or files to Base64 and decode Base64 back to its original form. Essential for embedding images in CSS, handling API authentication tokens, or debugging encoded data in network requests. Handles both text and binary files.

URL Encoder/Decoder

URL encoding is required for query parameters, form data, and API calls. This tool properly encodes special characters and decodes percent-encoded strings. Invaluable when debugging why your API call isn't working - often it's an encoding issue.

JSON Tools

A Swiss Army knife for JSON: format/prettify messy JSON, minify for production, validate syntax, and convert between JSON and other formats. When an API returns a wall of unformatted JSON, paste it here to actually read it.

Pretty Print

Format HTML, CSS, JavaScript, and JSON with proper indentation and syntax highlighting. When you're debugging minified code or copy-pasting from Stack Overflow, this makes the code readable again.

Diff Checker

Compare two pieces of text and see exactly what changed. Side-by-side or inline diff views, with options to ignore whitespace and case. Essential for code reviews, comparing config files, or figuring out what broke between versions.

Text Case Converter

Convert text between UPPERCASE, lowercase, Title Case, camelCase, snake_case, kebab-case, and more. Perfect for converting variable names between conventions or fixing text that was accidentally typed in caps lock.

CSS Minifier

Reduce CSS file size by removing whitespace, comments, and unnecessary characters. Smaller files = faster page loads. While build tools handle this automatically for most projects, this is perfect for quick one-off optimizations.

CSS REM Converter

Convert pixel values to REMs and vice versa. Enter your base font size and get instant conversions. REMs enable better responsive design and accessibility - this tool makes the math automatic.

Regex Tester

Test regular expressions in real-time with syntax highlighting, match highlighting, and capture group display. Regex is powerful but notoriously hard to debug - see exactly what your pattern matches before deploying it.

Generator Tools

Create test data, secure passwords, and unique identifiers instantly.

UUID Generator

Generate UUIDs (Universally Unique Identifiers) in various versions: UUID v1 (timestamp-based), v4 (random), and v7 (timestamp + random). Copy individual UUIDs or generate bulk lists for seeding test databases.

Password Generator

Create cryptographically secure passwords with customizable length and character sets (uppercase, lowercase, numbers, symbols). Generate pronounceable passwords that are easier to remember or maximum-entropy random strings for machine accounts.

Lorem Ipsum Generator

Generate placeholder text in various styles: classic Lorem Ipsum, hipster, corporate, or custom word lists. Specify paragraphs, sentences, or word count. Fill your mockups without writing "test test test" everywhere.

Placeholder Image Generator

Create placeholder images of any dimension with custom colors and text. Perfect for wireframes and prototypes when you don't have real images yet. Generate locally - no external service dependencies.

Hash Generator

Generate MD5, SHA-1, SHA-256, SHA-512, and other cryptographic hashes for text or files. Verify file integrity, create checksums, or generate hashed passwords (though please use proper password hashing libraries in production).

Credit Card Generator

Generate valid test credit card numbers for development and testing. These pass Luhn algorithm validation but aren't real cards - they're specifically designed for testing payment integrations without risking real transactions. Never use real card numbers in development.

Address Generator

Generate realistic fake addresses for testing forms, shipping integrations, and user profiles. Includes street, city, state, ZIP, and coordinates. Real address formats without being actual addresses - perfect for QA.

IP Address Generator

Generate random IPv4 and IPv6 addresses for testing network applications, logging systems, and IP-based rate limiting. Include options for specific ranges, reserved addresses, and bulk generation.

Cron Generator

Build cron expressions with a visual interface instead of memorizing the syntax. Select minutes, hours, days, and months, then see the cron string and human-readable explanation. Never Google "cron every 15 minutes" again.

.htaccess Generator

Generate Apache .htaccess rules for common tasks: redirects, URL rewrites, security headers, caching, and more. Select what you need, get the code, paste it in. Especially useful for WordPress sites and shared hosting environments.

Visual & Media Tools

Work with images, colors, and visual assets without installing desktop software.

Image Compressor

Reduce image file sizes without visible quality loss. Supports JPEG, PNG, WebP, and GIF. All processing happens in your browser - your images never leave your computer. Essential for page speed optimization.

Color Palette Generator

Generate harmonious color palettes from a base color: complementary, triadic, analogous, and more. Extract palettes from images. Get hex codes, RGB values, and HSL for each color. Perfect for design systems and brand guidelines.

Code Screenshot Tool

Turn code snippets into beautiful images for documentation, presentations, and social media. Syntax highlighting, customizable themes, backgrounds, and padding. Export as PNG or copy to clipboard.

SVG URL Encoder

Encode SVG files for use in CSS background-image properties. SVGs embedded this way are smaller and faster than separate HTTP requests. Paste your SVG, get the encoded CSS-ready URL.

QR & Barcode Tools

Generate and scan the codes that connect physical and digital worlds.

QR Code Generator

Generate QR codes for URLs, text, WiFi credentials, vCards, and more. Customize colors, add logos, adjust error correction levels. Download as PNG or SVG for print-quality output.

QR Code Scanner

Scan QR codes using your device's camera or by uploading an image. Instantly decode URLs, text, contact info, and other QR content. Works offline - the camera stream never leaves your device.

Barcode Generator

Generate various barcode formats: UPC-A, EAN-13, Code 128, Code 39, and more. Essential for inventory systems, product labels, and asset tracking. Download as images or print directly.

Authentication & Security

Decode tokens, test authentication flows, and understand security data.

JWT Decoder

Decode and inspect JSON Web Tokens without sending them to any server. See the header, payload, and verify signatures (if you provide the secret). Debug authentication issues without exposing tokens to third parties.

Timestamp Converter

Convert between Unix timestamps, ISO 8601, and human-readable dates. Handle timezone conversions. Essential for debugging logs, API responses, and any system that stores dates as numbers.

Content & Documentation

Preview and validate content before publishing.

Instant Markdown Viewer

Preview Markdown in real-time as you type. GitHub-flavored Markdown support with syntax highlighting, tables, and task lists. Perfect for writing README files, documentation, and blog posts before committing.

Font Awesome Validator

Check if Font Awesome icon names are valid and see them rendered. Paste an icon class and confirm it exists in the current Font Awesome version. Catches typos like "fa-calender" before they show up as missing icons in production.

Why Browser-Based Tools?

Every tool at RJL.io runs entirely in your browser. Your data never touches a server. This matters because:

• Privacy: Sensitive data (passwords, tokens, proprietary code) stays on your machine
• Speed: No network latency - processing happens instantly
• Offline: Most tools work without an internet connection
• Security: No server means no server-side vulnerabilities

For Website Owners Specifically

If you're managing a website (especially without a full development team), here's the toolset I'd recommend starting with:

1. SEO Analyzer - Run it on every page before publishing
2. Image Compressor - Use before uploading any image
3. Meta Tag Generator - Get your social sharing right
4. Favicon Generator - Create all sizes from one image
5. robots.txt Generator - Don't accidentally block Google

These five tools alone can dramatically improve your site's SEO, performance, and user experience.

Start Using These Tools

All 35 tools are free, require no signup, and work instantly. Visit RJL.io to explore the full collection. Bookmark the ones you use most - you'll be surprised how often they come in handy.

Stop context-switching to expensive apps for simple tasks. These tools exist to save you time and get you back to building.