Open sourcePlausible is the only one of the two you can run on your own server.
Plausibleyes · AGPL · self-hostable
Fathomno · proprietary
Pricing modelPlausible's entry tier is $6/mo cheaper. Beyond entry, the cost depends on your pageview volume + how many sites you track.
Plausiblefeature tiers · $9 Starter → $14 Growth → $19 Business · scales by pv via slider
Fathompageview tiers · $15 Starter → $60 Pro → $200 Business
Pageviews on entry tierFathom's entry tier includes 10× the pageviews. For sites over 10k pv/mo with a single site, Fathom's $15 may be simpler than scaling Plausible's Starter via slider.
Plausible10k pv base · 1 site on Starter ($9)
Fathom100k pv on Starter ($15)
Privacy postureBoth are equivalent on privacy. Both ship the cookie-free banner-free pitch.
Plausibleno cookies · GDPR/CCPA/PECR compliant
Fathomno cookies · GDPR/CCPA/PECR compliant
Dashboard / UXFathom's dashboard is the prettier one. Both are fast and clear.
Plausibleclean · functional · slightly utilitarian
Fathompolished · designer-focused · easier to share
Multi-siteBoth let you track unlimited domains within the pageview budget.
Plausibleunlimited sites on all plans
Fathomunlimited sites on all plans
Custom events / goalsBoth support custom event tracking. Slight UX differences but feature parity.
Plausiblefirst-class · custom events + funnels
Fathomfirst-class · events + goals
Email reportsFathom's email reports are nicer to look at; both convey the same info.
Plausibleweekly summary · per-site
Fathomweekly summary · per-site · slicker layout
API accessSelf-hosted Plausible gives you direct database access for custom queries.
PlausibleREST API · stats API · self-host gives you direct DB
FathomREST API · stats API
Data locationBoth are away from US data sovereignty if that matters. Pick whichever matches your residency requirements.
PlausibleEU (hosted) · anywhere (self-host)
FathomCanada · always