I know a few people who worked at Citymapper in senior roles, and the general consensus has always been that there was ultimately no feasible way to monetise.

I know a few people who worked at Citymapper in senior roles, and the general consensus has always been that there was ultimately no feasible way to monetise. As others have pointed out, their core value of routing/planning/exploiting Open Data became heavily commoditised by Apple, Google, and the transport operators themselves (e.g. TfL in London). Their belated attempts to monetise payments, data, even running transport itself, haven't been successful: it's a crowded, aggressive market filled with long-time incumbents who have established relationships and deep strategic control points. As a place to work / founder values... ..well, the reviews on Glassdoor speak for themselves. I can't say I'm grieving for its loss.