Hi HN, I’m one of the co-founders of Commet.

We built this because we were tired of the eventual consistency and “webhook hell' of traditional billing wrappers when trying to implement real-time usage tracking for AI tokens and seats.

The Core Idea: We provide a deterministic billing engine designed for complex models like metered usage, credits, and seat-based pricing, acting as a single source of truth for your app’s permissions. Beyond the logic, we also act as the Merchant of Record (MoR), taking on the global tax liability (VAT/GST) and compliance so you can offload the entire billing and tax infrastructure.

Tech Stack: Next.js, Go, and PostgreSQL. We focused heavily on idempotency and sub-100ms event ingestion.

We have a sandbox at sandbox.commet.co where you can test the API/SDK without an account. I’d love to hear your thoughts on the architecture, especially regarding how we handle multi-jurisdiction tax logic.

Happy to answer any questions!