Pre-launch: Abacus is pre-launch — the hosted API is not live yet, so the quickstart below runs against your own local instance of the open core today. At launch, paid plans claim their key on the claim page and the Starter plan signs up self-serve there.

curl -X POST http://localhost:8000/v1/meters \
  -H "X-API-Key: YOUR_API_KEY" -H "Content-Type: application/json" \
  -d '{"name":"api_calls","unit":"call","aggregation":"sum"}'

curl -X POST http://localhost:8000/v1/meters/api_calls/prices \
  -H "X-API-Key: YOUR_API_KEY" -H "Content-Type: application/json" \
  -d '{"unit_price_cents": 5, "currency": "usd", "upto": null}'

curl -X POST http://localhost:8000/v1/events \
  -H "X-API-Key: YOUR_API_KEY" -H "Content-Type: application/json" \
  -d '{"meter":"api_calls","customer":"cus_123","quantity":1,
      "idempotency_key":"evt_9f2c1a"}'
# {"id": 42, "deduped": false, "meter": "api_calls", ...}

curl "http://localhost:8000/v1/invoices/preview?customer=cus_123" \
  -H "X-API-Key: YOUR_API_KEY"
# {"lines": [{"meter":"api_calls","quantity":48210.0,
#   "unit_price_cents":5,"amount_cents":241050}], "total_cents":241050}

# Finalize burns prepaid wallet credits (if a wallet exists):
curl -X POST "http://localhost:8000/v1/invoices/finalize?customer=cus_123" \
  -H "X-API-Key: YOUR_API_KEY"

Full reference: every endpoint — method, path, auth, request and response shapes — is documented in OPENAPI.md in the product repo.