MRR stands for Monthly Recurring Revenue, so an "MRR app" is a tool that tracks that metric for subscription businesses.
The idea: if you charge customers monthly (SaaS, membership sites, subscriptions), your MRR is the total predictable revenue you can expect each month. It's the core health metric for any recurring-revenue business.
An MRR app typically lets you:
- Connect to your billing provider (Stripe, Paddle, etc.)
- See your MRR in real time, broken down by new, expansion, contraction, and churn
- Track growth trends over time
Popular standalone tools include Baremetrics, ChartMogul, and ProfitWell. Stripe also has basic MRR reporting built in now.
When someone says "I built an MRR app," they usually mean they built a small dashboard that pulls from their payment processor's API and shows these numbers. It's a pretty common indie hacker side project: once you've shipped a subscription product, you want a clean way to watch the numbers.