Credits & Top-ups

Credits let you use the API without a monthly subscription. Top up your balance, and usage is deducted automatically until your credits run out.

All endpoints require authentication.

Top up credits

POST /api/billing/topup

Request body

Parameter	Type	Required	Description
amount	number	Yes	Top-up amount in USD (minimum $10)
method	string	Yes	stripe or usdc

Stripe top-up

curl -X POST https://api.cheapestinference.com/api/billing/topup \
  -H "Authorization: Bearer YOUR_AUTH_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"amount": 50, "method": "stripe"}'

{
  "sessionUrl": "https://checkout.stripe.com/c/pay/cs_live_...",
  "sessionId": "cs_live_..."
}

USDC top-up

curl -X POST https://api.cheapestinference.com/api/billing/topup \
  -H "Authorization: Bearer YOUR_AUTH_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"amount": 50, "method": "usdc"}'

{
  "address": "0x...",
  "chain": "base",
  "amount": 25
}

---

Verify USDC top-up

POST /api/billing/verify-topup

After sending USDC on-chain, verify the transaction to credit your account.

Request body

Parameter	Type	Required	Description
txHash	string	Yes	Base L2 transaction hash
amount	number	Yes	Amount sent (must match)

Example

curl -X POST https://api.cheapestinference.com/api/billing/verify-topup \
  -H "Authorization: Bearer YOUR_AUTH_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"txHash": "0xabc123...", "amount": 25}'

Response

{
  "credited": 25,
  "balance": "75.00"
}

---

Check credit balance

GET /api/billing/credits

Returns your current credit balance and usage.

Example

curl https://api.cheapestinference.com/api/billing/credits \
  -H "Authorization: Bearer YOUR_AUTH_TOKEN"

Response

{
  "totalTopUp": "100.00",
  "remaining": "74.50",
  "hasCreditKey": true,
  "creditKeyId": "clx3ghi..."
}

Field	Description
totalTopUp	Total amount you’ve ever topped up
remaining	Current available balance (real-time tracking)
hasCreditKey	Whether you have a credit key
creditKeyId	ID of your credit key (if exists)

---

How credits work

Credit key

When you make your first top-up, a credit key is automatically created. This is a special API key with plan credits that uses budget-based tracking instead of subscription-based rate limits.

• The credit key has a 60 RPM rate limit
• There is no token-per-minute limit — spend is tracked in USD
• The system tracks max_budget and spend for the key
• When spend >= max_budget, further requests fail with a budget error

Shared balance

All credit usage for your account goes through your single credit key. The balance is shared — if you use it from multiple applications, they all draw from the same pool.

Top-up accumulation

Each top-up adds to your existing budget:

Current max_budget: $50, spent: $20 (remaining: $30)
Top up $25
New max_budget: $75, spent: $20 (remaining: $55)

Credits vs. Subscriptions

	Subscription	Credits
Payment	$20 or $60/month (one-time, 30 days)	$10+ per top-up
Rate limits	RPM + TPM per key	60 RPM only
Billing	Flat rate, unlimited usage within limits	Pay per token used
Expiration	30 days, then keys revoked	Never expires, consumed until depleted
Key creation	Manual, choose name and plan	Automatic on first top-up

You can have both an active subscription and credits simultaneously. Subscription keys use rate-limited access; credit keys use budget-based access.