Browser feature detection is the practice of checking whether a specific web API, CSS property, or JavaScript feature is available in the user's current browser. Instead of guessing based on browser name and version (user-agent sniffing), feature detection directly tests the capability, giving reliable results regardless of the browser.

Feature detection allows developers to implement progressive enhancement and graceful degradation. You can provide rich experiences for modern browsers while ensuring your site still works on older ones. It's more reliable than browser sniffing and helps avoid broken functionality on unsupported platforms.

This tool performs real-time, live detection using JavaScript and CSS APIs directly in your browser. Each feature is tested programmatically at runtime. Results are 100% accurate for your current browser, version, and settings. Features marked "Partial" may have limited availability (e.g., Service Workers require HTTPS).

"Partial" indicates the API exists but may have limitations. For example, Service Workers require a secure HTTPS connection to function, SharedArrayBuffer needs cross-origin isolation headers, and Cookies may be blocked by privacy settings even if the API exists. Always read the feature description for specific notes.

Use simple if statements in JavaScript (e.g., if ('geolocation' in navigator)) or @supports in CSS (e.g., @supports (display: grid)). Libraries like Modernizr also provide comprehensive detection. The key principle: test the feature, don't guess the browser.

Major browsers (Chrome, Firefox, Safari, Edge) release updates every 4-6 weeks. New web platform features are continuously added. We recommend re-checking your browser's capabilities periodically, especially after browser updates, as support for cutting-edge features like AVIF images or Container Queries can change rapidly.

Common gaps include AVIF image format (newer format, Safari added support in 2023), Web Bluetooth (Chromium-only), Payment Request API (varies by region), and SharedArrayBuffer (requires special server headers). Safari historically lags behind Chrome/Firefox on some newer APIs. Use this tool to identify exactly what your browser supports.