Balance and purchases
Top-ups, your rate, how a purchase is priced, and what happens to the balance.
Top-ups
Top up on the developer page, through Stripe Checkout. Each top-up is $250 to $10,000, and the balance can’t go above $50,000. For larger amounts, contact us: we can invoice you.
You get an invoice for each top-up. The money becomes balance as soon as Stripe confirms the payment.
Your rate
Your rate is a price per kg of CO₂, shown on the developer page and in GET /balance as rate_millicents_per_kg (thousandths of a cent): 4000 is $0.04 per kg, or $40 per tonne.
How a purchase is priced
- By volume:
{"kg": 1000}costskg × rate, rounded to the cent. At $0.04/kg that’s $40.00. - By price:
{"amount_cents": 5000}buys the most whole kg whose cost fits in the amount, and charges that cost, never more than the amount. At $0.035/kg, $50.00 buys 1,428 kg for $49.98.
Use POST /quotes to see both numbers before you buy.
A purchase that the balance doesn’t cover fails with 402 insufficient_balance; nothing is bought. The error tells you the balance and the cost.
Large purchases
Each account has a review limit, 15 t by default. A purchase above it is accepted and paid from the balance, but waits for our review before the credits are retired. POST /quotes tells you with requires_review.
If an order can’t be placed
We retry failed orders for you. If one still can’t be placed, we return its cost to your balance, and the offset becomes refunded.
Low balance email
Set a threshold on the developer page. We email you once when a purchase takes the balance below it. After a top-up lifts the balance above the threshold, the next drop below it emails you again.
Terms
The balance is prepaid and not refundable. It does not expire. It can only pay for API purchases, and you lose it if you delete your account. The terms have the details.