# Hybrid Model

**Subscriptions and Topups**

Many AI platforms start with subscriptions and later add topups to handle usage spikes.

Usage spikes can dramatically increase infrastructure spend, making subscription-only models insufficient for real-world profitability. That’s why a hybrid billing model, combining stable subscriptions with usage-based topups, is becoming prevalent in the AI economy.

Credyt supports this hybrid approach even if your subscriptions are already managed externally.

* **Subscriptions remain outside Credyt** - you keep using your existing PSP and billing system.

* **Credyt is informed when a subscription payment succeeds** via the Adjustments API, which credits the customer’s wallet.

* **Topups for additional usage** can be handled in two ways:

  <!-- -->

  * **Through Credyt** - using the Billing Portal or topup API (requires connecting a Stripe account).
  * **Outside Credyt** - process the payment with your PSP, then notify Credyt using the Adjustments API.

This lets you add real-time usage billing without rebuilding your subscription flow or changing payment providers.

## Implementation guide[​](#implementation-guide "Direct link to Implementation guide")

### Reflect Subscription Payments in Credyt[​](#reflect-subscription-payments-in-credyt "Direct link to Reflect Subscription Payments in Credyt")

[API Reference](https://docs.credyt.ai/api/customer-wallet-ops-create-adjustment.md)

When a subscription renews in your PSP, call the Adjustments API to increase the wallet balance:

* REST API
* TypeScript SDK
* Python SDK

POST https\://api.credyt.ai/customers/cust\_473cr1y0ghbyc3m1yfbwvn3nxx/wallet/adjustments

```json
{
  "transaction_id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "account_name": "default",
  "asset": "USD",
  "amount": 25,
  "description": "Monthly Subscription",
  "reason": "external_topup",
  "expires_at": "2024-07-29T15:51:28.071Z",
  "metadata": {
    "psp": "stripe",
    "payment_intent": "pi_3RjbbNJNSIruR1rb0GwMGpH0"
  }
}

```

**Response**

```json
{
  "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "created_at": "2024-07-29T15:51:28.071Z"
}

```

```typescript
await client.customerWalletOps.createAdjustment("cust_473cr1y0ghbyc3m1yfbwvn3nxx", {
  transactionId: "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  accountName: "default",
  asset: "USD",
  amount: 25,
  description: "Monthly Subscription",
  reason: "external_topup",
  expiresAt: "2024-07-29T15:51:28.071Z",
  metadata: {
    psp: "stripe",
    paymentIntent: "pi_3RjbbNJNSIruR1rb0GwMGpH0",
  },
});

```

[View full sample on GitHub](https://github.com/credyt/sdk-ts/blob/main/samples/walletsCustomerWalletOpsCreateAdjustmentSample.ts#L56)

**SDK response object**

```typescript
const response = {
  id: "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  createdAt: "2024-07-29T15:51:28.071Z",
};

```

```python
response = client.customer_wallet_ops.create_adjustment(
    customer_id="cust_473cr1y0ghbyc3m1yfbwvn3nxx",
    body={
    "transaction_id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
    "account_name": "default",
    "asset": "USD",
    "amount": 25,
    "description": "Monthly Subscription",
    "reason": "external_topup",
    "expires_at": "2024-07-29T15:51:28.071Z",
    "metadata": {
      "psp": "stripe",
      "payment_intent": "pi_3RjbbNJNSIruR1rb0GwMGpH0",
    },
  },
)

```

**SDK response object**

```python
response = {
  "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "created_at": "2024-07-29T15:51:28.071Z",
}

```

Wallet account balance increases by the subscription value.

### Handle Topups for Additional Usage[​](#handle-topups-for-additional-usage "Direct link to Handle Topups for Additional Usage")

[API Reference](https://docs.credyt.ai/api/customer-wallet-ops-create-adjustment.md)

**Option A: Use Credyt’s Payment Rails (Stripe Checkout)**

* Customer tops up via **Billing Portal** (self-service) or **Topup API** (your UI). Read about [Topups](https://docs.credyt.ai/features/wallets-and-topups.md).
* Credyt processes the payment through Stripe.
* Requires either creating a new Stripe account or connecting your existing one via Credyt.

**Option B: Keep Topups External**

* Process the payment with your PSP.
* Call the Adjustments API to reflect the new balance in Credyt.

- REST API
- TypeScript SDK
- Python SDK

POST https\://api.credyt.ai/customers/cust\_473cr1y0ghbyc3m1yfbwvn3nxx/wallet/adjustments

```json
{
  "transaction_id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "account_name": "default",
  "asset": "USD",
  "amount": 25,
  "description": "Ad-hoc usage",
  "reason": "external_topup",
  "expires_at": "2024-07-29T15:51:28.071Z",
  "metadata": {
    "psp": "stripe",
    "payment_intent": "pi_3RjbbNJNSIruR1rb0GwMGpH0"
  }
}

```

**Response**

```json
{
  "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "created_at": "2024-07-29T15:51:28.071Z"
}

```

```typescript
await client.customerWalletOps.createAdjustment("cust_473cr1y0ghbyc3m1yfbwvn3nxx", {
  transactionId: "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  accountName: "default",
  asset: "USD",
  amount: 25,
  description: "Ad-hoc usage",
  reason: "external_topup",
  expiresAt: "2024-07-29T15:51:28.071Z",
  metadata: {
    psp: "stripe",
    paymentIntent: "pi_3RjbbNJNSIruR1rb0GwMGpH0",
  },
});

```

[View full sample on GitHub](https://github.com/credyt/sdk-ts/blob/main/samples/walletsCustomerWalletOpsCreateAdjustmentSample.ts#L122)

**SDK response object**

```typescript
const response = {
  id: "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  createdAt: "2024-07-29T15:51:28.071Z",
};

```

```python
response = client.customer_wallet_ops.create_adjustment(
    customer_id="cust_473cr1y0ghbyc3m1yfbwvn3nxx",
    body={
    "transaction_id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
    "account_name": "default",
    "asset": "USD",
    "amount": 25,
    "description": "Ad-hoc usage",
    "reason": "external_topup",
    "expires_at": "2024-07-29T15:51:28.071Z",
    "metadata": {
      "psp": "stripe",
      "payment_intent": "pi_3RjbbNJNSIruR1rb0GwMGpH0",
    },
  },
)

```

**SDK response object**

```python
response = {
  "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "created_at": "2024-07-29T15:51:28.071Z",
}

```

### Send Usage Events[​](#send-usage-events "Direct link to Send Usage Events")

[API Reference](https://docs.credyt.ai/api/events-send-usage.md)

Once the wallet is funded (from subscription or topups), usage events will deduct balances in real time:

* REST API
* TypeScript SDK
* Python SDK

POST https\://api.credyt.ai/events

```json
{
  "customer_id": "cust_473cr1y0ghbyc3m1yfbwvn3nxx",
  "events": [
    {
      "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
      "event_type": "message_completed",
      "occurred_at": "2024-07-29T15:51:28.071Z",
      "subject": "chat_5f53d23a4958",
      "description": "Chat message completed",
      "data": {
        "model": "gpt-4-1",
        "input_tokens": 2353,
        "output_tokens": 34697
      }
    }
  ]
}

```

```typescript
await client.events.sendUsage({
  customerId: "cust_473cr1y0ghbyc3m1yfbwvn3nxx",
  events: [
    {
      id: "3fa85f64-5717-4562-b3fc-2c963f66afa6",
      eventType: "message_completed",
      occurredAt: "2024-07-29T15:51:28.071Z",
      subject: "chat_5f53d23a4958",
      description: "Chat message completed",
      data: {
        model: "gpt-4-1",
        inputTokens: 2353,
        outputTokens: 34697,
      },
    },
  ],
});

```

[View full sample on GitHub](https://github.com/credyt/sdk-ts/blob/main/samples/eventsSendUsageSample.ts#L11)

```python
response = client.events.send_usage(
    body={
    "customer_id": "cust_473cr1y0ghbyc3m1yfbwvn3nxx",
    "events": [
      {
        "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
        "event_type": "message_completed",
        "occurred_at": "2024-07-29T15:51:28.071Z",
        "subject": "chat_5f53d23a4958",
        "description": "Chat message completed",
        "data": {
          "model": "gpt-4-1",
          "input_tokens": 2353,
          "output_tokens": 34697,
        },
      },
    ],
  },
)

```

[View full sample on GitHub](https://github.com/credyt/sdk-python/blob/main/samples/events_send_usage_message_completed.py#L20)