Will it sound distorted?

Not at a reasonable level. The maximizer limits peaks with a ceiling to prevent digital clipping.

Is it the same as mastering?

Not quite. Raising volume is one part; mastering also handles tone, dynamics and consistency.

Yes, and of WAV too. For the best final quality, work from WAV if you have it.

Online audio tool

When your audio is too quiet, raise it evenly and without distortion. The maximizer lifts the level and controls the peaks.

Target search: increase volume of a song

Upload your song or audio.

Choose how much to raise the level.

Check it does not distort in the preview.

Download the louder, more even version.