In one paragraph
Heap's autocapture-everything model is a real productivity boost if your team retro-defines events months after they fired. Millimetric makes the opposite bet: name the event when you write the code, and you'll thank yourself later. Smaller bundle, cleaner data.
Pick Heap when…
- You expect to retroactively define events you didn't plan for.
- Your team won't instrument manually.
- You're already on Heap and the data is your moat.
Pick Millimetric when…
- You want clean, intentional event names.
- You care about bundle size.
- You want privacy by default — no IPs at rest, no behavioral fingerprint.
Feature
Millimetric
Heap
- Capture modelExplicitAutocapture
- Bundle size1.8 KB~60 KB
- MCPNativeNo
- Retroactive event definitionNoYes
Last reviewed May 2026. Spotted an out-of-date detail? Tell us.
Our verdict
Heap if you'll retroactively define events. Millimetric if you'll define them at write time.