Arlo is a secure tool for conducting Risk-Limiting Audits (RLAs) used by 10 states. It was developed by VotingWorks with support from the U.S. Department of Homeland Security.
The code for Arlo is open-source and freely available for anyone to use. VotingWorks optionally provides hosting and support to states and local jurisdictions.
Hosted Arlo state subscriptions are $0.0075 per registered voter per year with a $15,000 minimum.