Polyfill Injector & Detector

Tag: Polyfill Injector & Detector

2+ tools

New

CSS Custom Property Polyfill Checker - Online IE11 Fallback

Paste your CSS and see a static fallback version where var() is replaced with the default value. For legacy support.

Developer Tools CSS variables fallback legacy polyfill

New

EventSource Polyfill Demo - Online See SSE with Custom Headers

Demonstrate how to add custom headers and POST‑like functionality to EventSource using a polyfill. Code and example.

Developer Tools demo EventSource polyfill SSE