Does converting FLAC to MP3 lose quality?
Yes, MP3 is a lossy format, so some detail is always discarded. At 320 kbps most people cannot hear the difference. Keep the FLAC file as your lossless master and use the MP3 for phones and sharing.
Which MP3 bitrate should I pick?
320 kbps for the best quality, 192 kbps for a good balance, and 128 kbps for the smallest files. A FLAC album that takes 400 MB lands around 100 MB as 320 kbps MP3s.
Is my music uploaded to a server?
No. The conversion runs entirely in your browser, so your files never leave your device. Files up to 200 MB are supported, free and without a sign-up.