Online Free Audio Cutter Online UniConverter allows you to compress audio files online free and without losing quality. The compressed files can be saved to Dropbox or downloaded directly. How to compress audio files? Step 1. Click the Audio Compressor extension icon on the top right corner of your Chrome browser. It will open an online free Audio Compressor. Step 2. Drag and drop or click the Choose Files button to import audio files you want to compress. Step 3. Choose an output format like MP3 from the Convert all files to > Audio tab. Step 4. Hit the CONVERT button to start the audio compression process. Step 5. Click the DOWNLOAD or Save to Dropbox button to get the compressed files.