Checkers
Browser Feature Detector
Detect which web APIs and CSS features your browser supports. Tests 36 features across Core, CSS, APIs, and Storage categories.
Free Web Developer Tools
Online utilities for developers โ formatters, generators, converters, and more. All tools run in your browser, no data is sent to any server.
Checkers
Contrast Checker (WCAG)
Check color contrast ratios against WCAG 2.1 AA and AAA guidelines for accessible web design.
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Diff Checker (Text Compare)
Compare two texts side-by-side with highlighted additions, deletions, and line numbers. Unified and split view modes.
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Encoding Detector
Detect text encoding format: UTF-8, Base64, URL-encoded, HTML entities, hex, binary, JWT. Auto-decode detected formats.
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Headline Analyzer
Analyze headlines for effectiveness. Score based on word count, power words, emotional impact, and readability.
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Keyword Density Checker
Check keyword density in your content. Analyze word frequency, n-gram phrases, and optimize for target keywords.
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Password Strength Analyzer
Analyze password strength in real-time. Check entropy, character diversity, crack time estimates, and get improvement suggestions.
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Readability Score Calculator
Calculate readability scores including Flesch Reading Ease, Flesch-Kincaid Grade, Gunning Fog, and more.
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Regex Tester
Test regular expressions in real-time with match highlighting, capture group details, and flag support.
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Responsive Breakpoint Viewer
Preview websites at common responsive breakpoints. Test mobile, tablet, and desktop views with custom dimensions.
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Screen Resolution Detector
Detect your screen resolution, viewport size, device pixel ratio, color depth, and matching device name. Live updates on resize.
Checkers
SSL Certificate Decoder
Decode and inspect PEM-encoded SSL/TLS certificates. View subject, issuer, validity dates, and Subject Alternative Names.
Calculators
Unix Permissions Visualizer
Visualize and calculate Unix file permissions. Convert between octal, symbolic notation, and interactive checkboxes.
Checkers
Word & Character Counter
Count words, characters, sentences, and paragraphs with reading time estimation and keyword frequency analysis.