How Northstar Labs cut their billing backend to one POST

The problem

Northstar Labs is a two-person AI tools team running customer-support agents across three independent SaaS products. Every reply their agents send costs real LLM tokens — and historically, Northstar ate that cost themselves. They couldn't bill end customers per resolution outcome, so high-volume products subsidized by-product-month margin and high-volume low-revenue products ran hot on cost-of-goods.

Their billing backend was a Stripe webhook stitched together with a Slack alert on every charge and a spreadsheet the founders reconciled manually each Friday. Adding a new product to bill required a deploy, a new Slack channel, and a new tab in the spreadsheet. The founders spent more time reconciling invoices than shipping product.

They needed one place to meter agent runs, charge per token, pay themselves on successful outcomes, and surface per-product revenue without spinning up another internal tool. That's what Rev is for.

Before / After

Implementation

1. Sign up at /signup, copy the API key from the dashboard.
2. Add one Rev meter call to the agent code, fired after each support reply completes.
3. Rev charges the end customer the configured token rate and books an outcome bonus on each resolution.
4. Revenue per product line, per customer, and per agent action shows up live in the dashboard.
5. No Stripe code, no Slack channel, no spreadsheet — Rev handles the billing rails end-to-end. The integration looks exactly like this:

curl -X POST https://rev.polsia.app/v1/meter \
  -H "Authorization: Bearer " \
  -H "Content-Type: application/json" \
  -d '{
    "customer_id": "user-123",
    "action": "support_reply",
    "tokens": 412,
    "outcome": true
  }'