Scope, and this is the one that changed. As of our check on 6 September 2026, Umami does heatmaps and session replay. Plausible does neither and does not claim to. For most of these two products' lives that row read the same for both, so a comparison written a year ago, and there are many still online, gets this exactly backwards. If watching behaviour matters at all, the comparison ends here.
Money. Plausible has no free tier: you pay from the first day. Umami's cloud has one. Both are open source and both can be self-hosted at no licence cost, so "free" describes three different arrangements in one sentence (free cloud tier, free to run yourself, and not free at all) and which one you mean decides the answer.
Where the data sits. Plausible states that EU visitor data is processed on EU infrastructure. For Umami it depends on where you put it: self-hosted, that is your decision and your strongest possible answer; on their cloud, it depends on the region. Neither position is worse, but only one of them is a promise you can quote to somebody else without checking first.
What they agree on, which is most of it. Neither stores anything on the visitor's device, so neither needs a consent banner. Neither samples. Both report traffic sources, both are open source, both are self-hostable, and neither measures apps. That is a lot of agreement, and it is why the two differences above carry the whole decision.