As part of the ElevenLabs Startup Grant program, we were able to convert most of our historical markers and stories into high-quality audio. They have a great voice selection - although they are a bit on the expensive end.
MongoDB has been great to help get our app going and provide a solid offline mode - with the deprecation of their App Service platform, we'll be working to migrate to another database that includes Application Services (auth, sync, functions, triggers, etc).
HMDB has been aggregating Historical Markers for over 15 years. Their database is the best out there and forms the base for the ExploreHere app. We used their data and enhanced it with summaries, rich audio, and an interactive map that lets you explore markers around you, wherever you go.
