# ect > Efficient Compression Tool (or ECT) is a C++ file optimizer. It supports PNG, JPEG, GZIP and ZIP files. > More information: . - Compress a file: `ect {{filename.png}}` - Compress a file with the highest compression level and multithreading: `ect -9 --mt-deflate {{filename.png}}` - Compress all the files in a directory recursively, keeping the original modification time: `ect -keep -recurse {{directory}}`