OpenMeter

OpenMeter is an open-source metering and billing engine designed to track usage, enforce limits, and automate invoicing for AI, agentic, and DevTool monetization. The software is deployed as a server and can be run locally via Docker Compose or in production using a Helm chart for Kubernetes, allowing organizations to maintain control over their billing infrastructure.

Users ingest events through an API in CloudEvents format to define meters with various aggregations. The platform connects this usage data to billing cycles, entitlements, and customer dashboards, enabling a transition from simple subscriptions to complex usage-based pricing. It provides dedicated SDKs for Go, JavaScript, Node.js, and Python to facilitate the integration of event tracking into existing application workflows and backend services.

Key features

• Usage metering with SUM, COUNT, AVG, MIN, and MAX aggregations
• Usage-based billing supporting tiered, graduated, and flat-fee pricing
• Real-time usage limits, quotas, and boolean feature flags
• Product catalog for managing plans, add-ons, and rate cards
• Prepaid and promotional credit grants with priority-based burn-down
• Token-based self-service customer portals for usage visibility
• Webhook-based notifications for usage thresholds and billing events
• Specialized metering for LLM token usage and model-specific costs

The architecture is built in Go and optimized for high-volume event ingestion and real-time processing. It utilizes Kafka for the event streaming pipeline to handle incoming data, ClickHouse for real-time usage aggregation and analytics, and PostgreSQL for managing subscriptions, entitlements, and the product catalog. The API is designed using TypeSpec to ensure consistent OpenAPI specifications across its SDKs, making it suitable for developers who need to scale their metering logic without sacrificing performance.

OpenMeter is a FinOps tool for companies implementing usage-based pricing models and complex monetization strategies.