What is a synonym for the expression voila?

There isn't a perfect synonym for "voila" because it's a very specific interjection. However, depending on the context, some options could be:

Expressing surprise or success:

* There you have it!

* And there you go!

* Ta-da!

* Behold!

* Here it is!

* See?

Expressing completion or satisfaction:

* That's it!

* Done!

* There you go!

* Finished!

* Perfect!

Ultimately, the best synonym for "voila" will depend on the specific situation and the intended meaning.