When this matters
MAU matters once pricing, investor decks, product health, or growth reporting start depending on user activity instead of raw pageviews. A lot of developer tools also use MAUs to meter auth or backend pricing.
Common mistake or lookout
Treating every signup like an active user. MAU usually means someone actually used the product, not just created an account and disappeared.
Why this matters for vibe coders
Vibe coders often focus on shipping first and pricing second. Understanding MAUs helps you spot when a “cheap” tool can become more expensive as real usage arrives.