Are there any open source DEFLATE encoder implementations for JavaScript? I need it to generate a binary format on the client-side that requires DEFLATE.
I believe Pako (https://github.com/nodeca/pako) is now the fastest javascript implementation of deflate and other zlib methods (inflate / gzip / ungzip). There are benchmarks on the github page. It also supports chunking if you need to work with big blobs.
Disclaimer: I am the author of this code.