If the free version of MixPad doesn't meet your needs, consider these powerful, 100% free, and open-source alternatives:
NCH Software offers a free version of MixPad specifically for non-commercial, home use. This version does not require a registration code or a paid license to operate, making it the safest "exclusive free" option available. Mix an unlimited number of music, vocal, and audio tracks. nch mixpad registration code exclusive free