Billing & Subscriptions

All billing endpoints require authentication unless noted otherwise.

Authorization: Bearer YOUR_AUTH_TOKEN

Subscribe (checkout)

POST /api/billing/checkout

Start a subscription checkout. Returns a payment URL (Stripe) or wallet instructions (USDC).

Request body

Parameter	Type	Required	Description
planSlug	string	Yes	standard or pro
method	string	Yes	stripe or usdc

Stripe checkout

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

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

Redirect the user to sessionUrl. After payment, Stripe sends a webhook and the subscription activates automatically.

USDC checkout

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

{
  "address": "0x...",
  "chain": "base",
  "amount": "60",
  "planSlug": "pro"
}

Send the exact USDC amount to the address on Base L2, then verify the transaction.

---

Verify USDC payment

POST /api/billing/verify-payment

After sending USDC on-chain, call this endpoint with the transaction hash to activate your subscription.

Request body

Parameter	Type	Required	Description
txHash	string	Yes	Base L2 transaction hash
planSlug	string	Yes	standard or pro

Example

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

Response

{
  "activated": true,
  "expiresAt": "2026-03-15T10:00:00.000Z"
}

The backend verifies the USDC transfer on-chain (correct recipient, correct amount) before activating.

---

Subscription status

GET /api/billing/status

Returns the current subscription and billing state.

Example

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

Response

{
  "plan": "pro",
  "status": "active",
  "subscriptionExpiresAt": "2026-03-15T10:00:00.000Z",
  "stripeCustomerId": "cus_...",
  "creditBalance": "25.00"
}

Field	Description
plan	Current plan slug (standard, pro, or null)
status	active, expired, pending, or null
subscriptionExpiresAt	When the current 30-day period ends
creditBalance	Pay-as-you-go credit balance in USD

If status is active but subscriptionExpiresAt is in the past, the endpoint automatically marks the subscription as expired and returns expired.

---

Cancel subscription

POST /api/billing/cancel

Cancels your subscription. Keys remain active until the current period expires.

Example

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

Response

{
  "canceled": true,
  "expiresAt": "2026-03-15T10:00:00.000Z"
}

---

Payment address

GET /api/billing/payment-address

Returns the USDC payment address and chain for direct payments.

Response

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

---

How subscriptions work

• Subscriptions are 30-day one-time purchases — there is no auto-renewal.
• After 30 days, the subscription expires and all API keys are automatically revoked.
• To continue, purchase a new subscription and create new keys.
• You can pay with credit card (Stripe) or USDC on Base L2.

Expiration

An hourly cron job checks for expired subscriptions. When your subscription expires:

1. All active API keys are revoked
2. Your subscription status is set to expired
3. Your plan is cleared

Credit keys are not affected by subscription expiration — they remain active as long as you have credit balance.