IconVault's Gzip Tool compresses and decompresses right in the tab. Paste text or drop a file to compress it with real gzip via the browser-native CompressionStream API, and see the before and after sizes plus the exact compression ratio before you download the .gz file or copy it as base64.

Flip to the decompress tab to expand a .gz file or base64 gzip data back to text. It is free with no signup and runs fully in your browser, your files never leave your device. The honest caveat: compression uses your browser's built-in gzip, so very old browsers without CompressionStream cannot run it, and already-compressed files like JPEGs or ZIPs will barely shrink.