Truthly.ai offers an app for Android and iPhones for a subscription price of $29.99 per year. It does not cite sources, and always poses a reflection question at the end of each answer. Catholic podcaster Matt Fradd is one co-founder.
Magisterium.com offers answers from thousands of magisterial documents and cites sources in its answers. One can pose 90 prompts per week for free, or an unlimited number for $29.99 per year. I’ve found this service to be the most helpful in locating magisterial documents on any given topic.
MasterCatechism.com offered by Tradivox. Answers can be chosen to be in “Classic” or “Contemporary” format, with the former heavily relying upon Bishop Athanasius Schneider’s catechism, Credo. It seems to be free, but Tradivox accepts donations.
