There are quite a few, but I use Steem Voter and Minnow booster they seem to work quite well, I dont really have much time to spend on steemit so I try to share my vote with a group of people who's posts I really like.
These are the links:
https://steemvoter.com/
https://www.minnowbooster.net/
Can be a bit tricky to get used to working it, but there are posts regarding it on here and maybe even just google to check how they work, much to involved to explain the working here.
Best of luck :-) you can add me if you want :-) michaeljn