Text ⇄ gzip ⇄ Base64 in your browser using the native CompressionStream API. No upload, no server.
Type text and click Compress → Base64: the text is UTF-8-encoded and gzip-compressed via the native CompressionStream('gzip') API, then the compressed bytes are Base64-encoded for easy copy / paste. Paste Base64 (gzipped) on the other side and click Decompress to recover the text. Stats show input size, compressed size and ratio. Large inputs are processed in a single stream; if your browser does not support CompressionStream, an error is shown. Everything stays in your browser.