OpusEvent (Opus Audition) Acceptd
OpusEvent has provided software for music auditions since 2006, mostly serving student competitions. The platform has added features over the years, such as registration payments and online submission, but has lagged far behind in usability. In other words, while new features have been added, the platform is severely outdated.
Pricing for OpusEvent audition platform can be found here. Pricing is per application (audition registration) and ranges from $2 to $6.
Snap Audition
Snap Audition is an online platform focused on making auditions easier to run. The focus of Snap is just that - running auditions from small to complex.
Snap's system has three main functions: 1) Management, 2) Registering, and 3) Judging. With the same Snap Account (login), you can do all three roles and for multiple organizations. Go here to learn more about Snap's features.
Snap is absolutely free to use for up to 100 auditions a year. If you need more auditions or, multiple organization admins or judges, it's $2-$3 per audition, or free to use if you choose for the entrant to pay. In that case, it's $5.50 per audition (unlimited rounds).