The best project by far is osm2vectortiles.org. It pretty much allows you to have a global OSM map on a USB stick, or render it live from a 4 GB VPS.
There is one critical issue which needs to be solved though, Mapbox reached out to them and asked them to rebuild everything from scratch [2], which means that it'll be a few more months before it's legally "safe" to use vector tiles produced by this project.
Depending on the application, you can get pretty far with the Data Science Toolkit's geo data[1], some boundary data [2], and something like Leaflet JS[3]. It won't support pathfinding out of the box, but you can do (bidirectional) geocoding, map rendering, state/county/city-level labelling/border-drawing, and lots of other cool stuff.