There are at least three artists with this name: a lds band from Toronto and a russian experimental rock band from Saint Petersburg, and an American six-man a cappella group.

1. Toronto, Ontario (1999 - 2008)
Insideout is a Toronto band active from 1999 until 2008 consisting of Joren Cull & AJ Ing. In that time span they have managed to release 29 albums of original material. They have been on hiatus since 2008.

2. Saint Petersburg, Russia (2016 - present)
Another InsideOut is a duo from Saint Petersburg formed in 2016. Their sound has been described as experimental and atmospheric synthesis of bright guitars and synths. First EP named Dive was released September 1st 2016.
The band consists of Arseniy Schedrin (vocals, guitar) and Mikhail Chernyakhovsky (drums and percussion).

3. Utah, United States (1999 - present)
InsideOut is a six-man vocal band. Since its inception in 1999, the group has toured the U.S., published six albums, and thrilled audience members old and young. Their unique style combines contemporary a cappella, comedy and a lot of charm. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.