Monthly Active Users

What it means

Monthly Active Users, or MAU, is the number of distinct users who take a qualifying action inside a product during a rolling or calendar month. In the feature flag world the term has a second, more commercial meaning. Most SDKs report each unique context they evaluate flags for, and vendors count those unique identities as billable MAU (sometimes called Monthly Active Contexts or seats depending on the tool).

Why it matters

MAU is the unit that many pricing plans meter, so a small change in how you identify users can swing your bill. Anonymous visitors, bots, service accounts, and per-device contexts can all inflate the count if you send a fresh identifier for each one. Teams that treat every request as a new user often pay far more than teams that reuse stable keys. Understanding exactly what your provider counts is the first step to keeping cost predictable as traffic grows.

In practice

Say a site sends a new random context key on every page load. Each load looks like a new user, so MAU balloons and the invoice climbs even though real usage is flat. The fix is to key contexts on a durable value such as an account id or a persisted cookie so returning visitors collapse into one billable identity. Tools like LaunchDarkly and Statsig publish how they tally active identities, and our guide to reducing LaunchDarkly costs walks through trimming the count without losing targeting precision.