Orb is a usage-based billing platform designed for B2B SaaS companies that need flexible pricing models beyond simple subscriptions. It provides sophisticated metering infrastructure to track product usage in real-time, transform raw events into billable metrics, and generate accurate invoices. The platform excels at handling complex pricing scenarios including tiered pricing, hybrid models, and custom billing logic. While powerful and developer-friendly with excellent API documentation, it requires careful implementation planning and is primarily built for companies with significant billing complexity.