> ## Documentation Index
> Fetch the complete documentation index at: https://docs.flexprice.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Build Usage-based Pricing like Vapi.ai

> Vapi is a developer platform for building, testing, and deploying realistic, human-like voice AI agents.

## Overview

Vapi uses a modular, usage-based pricing model where you pay for distinct components.

## Pricing Breakdown

<Frame>
  <img
    src="https://mintcdn.com/flexprice/1zrPv-zyr6UVa0LY/public/images/docs/subscription-flow/boiler-plate-vapi-pricing.png?fit=max&auto=format&n=1zrPv-zyr6UVa0LY&q=85&s=b22a59df986685799b5ae9a88763a660"
    alt="Feature
Module"
    width="2896"
    height="1194"
    data-path="public/images/docs/subscription-flow/boiler-plate-vapi-pricing.png"
  />
</Frame>

## 1. Key Chargeable Features in Vapi

* Vapi charges customers primarily for **hosting and orchestration**, not for the underlying AI or telecom providers directly.

### A. Hosting Fee for Call Minutes

It charges a **fixed hosting fee per call minute.**

**Pricing (Pay As You Go):**

* **\$0.05 per minute**

***

### B. Hosting Cost for SMS / Chat Messages

It also charges a **fixed hosting fee per message.**

**Pricing (Pay As You Go):**

* **\$0.005 per message**

***

## 2. Fixed Fees vs Usage-Based Charges

Pricing consists of **fixed per-unit fees**, not bundled plans or feature-based tiers.

### Fixed Fees (Platform Hosting Costs)

These fees are **fixed per unit of usage**:

| Feature            | Pricing Model | Cost          |
| ------------------ | ------------- | ------------- |
| Call Hosting       | Per minute    | \$0.05 / min  |
| SMS / Chat Hosting | Per message   | \$0.005 / msg |

These fees remain the same regardless of scale (Pay As You Go).

***

### Usage-Based Scaling

| Usage Dimension   | Pay As You Go                     | Enterprise   |
| ----------------- | --------------------------------- | ------------ |
| Call Minutes      | Usage based                       | Custom       |
| SMS / Chat Volume | Usage based                       | Volume based |
| Call Concurrency  | 10 included + \$10 / line / month | Custom       |

***

## 3. Call Concurrency Pricing

Call concurrency determines **how many simultaneous calls** your system can handle.

### Pay As You Go

* **10 concurrent calls included**
* **\$10 per additional line per month**

### Enterprise

* Custom concurrency limits
* Volume-based pricing
* SLA-backed infrastructure

***

## 4. Enterprise Pricing Model

The **Enterprise plan** operates under an **annual contract** with custom pricing.

**Enterprise features include:**

* Custom call minute pricing
* Volume-based SMS and chat pricing
* Priority support and SLAs

> Enterprise pricing is negotiated directly with the Vapi sales team.

## Complete Flow Summary

The complete subscription flow for Vapi usage-based pricing:

1. Create Features (Call Minutes, SMS/Chat)
   ↓
2. Create Plans (Pay As You Go with usage charges)
   ↓
3. Create Customer (with External ID)
   ↓
4. Create Subscription (link customer to plan)
   ↓
5. Send Usage Events (via API)
   ↓
6. Verify Events (using Event Debugger)
   ↓
7. Billing (automatic at end of billing cycle)
   ↓
8. Review Invoices (Customer Info)

## Flexprice Set-up

To configure Vapi's usage-based pricing in Flexprice, follow these steps in order:

<Steps>
  <Step title="Step 1: Create Features">
    Navigate to **Flexprice Dashboard** → **Product Catalog** → **Features**

    Click **"Create Feature"** to start creating features. You need to create two metered features:

    <Frame>
      <img
        src="https://mintcdn.com/flexprice/1zrPv-zyr6UVa0LY/public/images/docs/subscription-flow/create-feature-example.png?fit=max&auto=format&n=1zrPv-zyr6UVa0LY&q=85&s=deb16229b007936cc4c5e35c0fd593b4"
        alt="Feature
Module"
        width="1700"
        height="2200"
        data-path="public/images/docs/subscription-flow/create-feature-example.png"
      />
    </Frame>

    **Feature 1: SMS / Chat Hosting**

    * **Feature Name**: `SMS / Chat Hosting`
    * **Feature Lookup\_key**: `sms_chat_hosting` (immutable, unique identifier)
    * **Feature Type**: `Metered`
    * **Event Name**: `sms.chat.message` (must match exactly when sending events)
    * **Aggregation Method**: `Sum`
    * **Aggregation Field**: `messages`
    * **Unit**: `message` or `msg`
    * **Description**: `Vapi hosting cost for SMS and chat messages - covers message delivery, session handling, and conversational state management`

    > **Note**: The Event Name must match exactly when you send usage events via API. Save these event names for later use.

    For comprehensive information on creating features, see [Features](/docs/product-catalogue/features/create).
  </Step>

  <Step title="Step 2: Create Pricing Plans">
    Navigate to **Flexprice Dashboard** → **Product Catalog** → **Plans**

    Click **"Add"** at the top-right to create a new plan.

    **Create Pay As You Go Plan:**

    <Frame>
      <img
        src="https://mintcdn.com/flexprice/1zrPv-zyr6UVa0LY/public/images/docs/subscription-flow/create-plan-example.png?fit=max&auto=format&n=1zrPv-zyr6UVa0LY&q=85&s=ca47bc488ff3406fdc5d2c620223c60d"
        alt="Feature
Module"
        width="2922"
        height="1428"
        data-path="public/images/docs/subscription-flow/create-plan-example.png"
      />
    </Frame>

    **Step 2.1: Plan Details**

    * **Plan Name**: `Pay As You Go`
    * **Lookup Key**: `pay_as_you_go` (immutable, unique identifier)
    * **Plan Description**: `Usage-based pricing plan with flat fees for call minutes and SMS/chat messages`
    * Click **Next** to proceed to charge configuration

    **Step 2.2: Define Usage-Based Charges**

    **Charge 1: SMS / Chat Hosting**

    * **Select Metered Feature**: `SMS / Chat Hosting` (sms\_chat\_hosting)
    * **Billing Currency**: `USD`
    * **Billing Period**: `Monthly`
    * **Billing Model**: `Flat Fee`
    * **Price per Unit**: `0.005` (per message)
    * **Billing Timing**: `Arrears Billing` (bill at end of cycle)
    * Click **Add** to save this charge

    Click **Save** to finalize the Pay As You Go plan.

    For comprehensive information on creating plans, see [Creating a Plan](/docs/product-catalogue/plans/create).
  </Step>

  <Step title="Step 3: Create Customer">
    Navigate to **Flexprice Dashboard** → **Customer Management** → **Customers**

    Click **"Add Customer"** to create a new customer.

    **Required Fields:**

    * **Customer Name**: `Acme Corporation` (or your customer's name)
    * **External ID**: `cust_acme_001` (unique identifier from your system)

    **Optional Fields:**

    * **Email**: Customer's email address
    * **Phone**: Customer's phone number
    * **Address**: Customer's billing address

    > **Important**: The External ID is what you'll use when sending usage events. Make sure it matches exactly.

    Click **Save** to create the customer.

    For comprehensive information on creating customers, see [Customer Management](/docs/customers/create).
  </Step>

  <Step title="Step 4: Create Subscription">
    Navigate to **Flexprice Dashboard** → **Customer Management** → **Customers**

    Click on the customer you created to open their details page.

    Click **"Add Subscription"** button.

    **Subscription Configuration:**

    * **Select Plan**: Choose `Pay As You Go` from the dropdown
    * **Subscription Start Date**: Select the start date for billing (e.g., today's date)
    * **Subscription End Date**: Leave as "Forever" for ongoing subscriptions, or set a specific end date
    * **Billing Cycle**: This determines when billing cycles start (usually the start date)

    The subscription preview will show:

    * All recurring charges (if any)
    * Usage-based charges that will be billed based on consumption
    * Estimated costs for the billing period

    Click **Add Subscription** to save.

    The subscription will now appear under the customer's details with status "Active".

    For comprehensive information on creating subscriptions, see [Create Subscription](/docs/subscriptions/customers-create-subscription).
  </Step>

  <Step title="Step 5: Create Usage Events">
    Once a customer has an active subscription, you can start sending usage events to Flexprice via API.

    **API Endpoint:**

    ```
    POST https://api.cloud.flexprice.io/v1/events
    ```

    **Authentication:**
    Include your API key in the request header:

    ```
    x-api-key: <your_api_key>
    ```

    **Example 1: Send SMS/Chat Message Event**

    ```bash theme={null}
    curl --request POST \
      --url https://api.cloud.flexprice.io/v1/events \
      --header 'Content-Type: application/json' \
      --header 'x-api-key: <your_api_key>' \
      --data '{
        "event_name": "sms.chat.message",
        "external_customer_id": "cust_acme_001",
        "properties": {
          "messages": 1
        },
        "event_id": "evt_sms_67890",
        "timestamp": "2025-01-15T10:35:00.000Z",
        "source": "vapi-platform"
      }'
    ```

    **Example 2: Bulk Events (Multiple Events at Once)**

    ```bash theme={null}
    curl --request POST \
      --url https://api.cloud.flexprice.io/v1/events/bulk \
      --header 'Content-Type: application/json' \
      --header 'x-api-key: <your_api_key>' \
      --data '{
        "events": [
          {
            "event_name": "call.minutes",
            "external_customer_id": "cust_acme_001",
            "properties": { "minutes": 10 },
            "source": "vapi-platform"
          },
          {
            "event_name": "sms.chat.message",
            "external_customer_id": "cust_acme_001",
            "properties": { "messages": 3 },
            "source": "vapi-platform"
          }
        ]
      }'
    ```

    **Event Payload Fields:**

    * **event\_name** (required): Must match your feature's Event Name exactly (`call.minutes` or `sms.chat.message`)
    * **external\_customer\_id** (required): Must match the customer's External ID (`cust_acme_001`)
    * **properties** (required): Contains the aggregation field value
      * For Call Minutes: `{"minutes": <number>}`
      * For SMS/Chat: `{"messages": <number>}`
    * **event\_id** (optional): Your unique identifier for the event
    * **timestamp** (optional): ISO 8601 UTC timestamp. If omitted, server time is used
    * **source** (optional): Origin of the event (e.g., "vapi-platform", "api")

    **Response:**

    ```json theme={null}
    {
      "event_id": "event_01K389J4M1F1NZG6XP0AMD6J52",
      "message": "Event accepted for processing"
    }
    ```

    For comprehensive information on sending events, see [Sending Events](/docs/event-ingestion/sending-events).
  </Step>

  <Step title="Step 6: Verify Events with Event Debugger">
    After sending usage events, verify they are being processed correctly using the Event Debugger.

    **Navigate to Event Debugger:**

    1. Go to **Flexprice Dashboard** → **Usage Tracking** → **Event Debugger**

    **View Events:**
    The Event Debugger displays a real-time stream of events with:

    * **Event ID**: Unique identifier for each event
    * **Event Name**: The feature being tracked (`call.minutes` or `sms.chat.message`)
    * **Customer Lookup Key**: Customer's External ID
    * **Source**: Origin of the event
    * **Timestamp**: When the event occurred

    **View Event Details:**
    Click on any event to view the complete payload:

    ```json theme={null}
    {
      "id": "event_01",
      "external_customer_id": "cust_acme_001",
      "event_name": "call.minutes",
      "timestamp": "2025-01-15T10:30:00.000Z",
      "properties": {
        "minutes": 5.5
      },
      "source": "vapi-platform"
    }
    ```

    **Filter Events:**
    Use filters to find specific events:

    * **Filter by Event Name**: `event_name contains "call.minutes"`
    * **Filter by Customer**: `external_customer_id contains "cust_acme_001"`
    * **Filter by Time Range**: Set Start Time and End Time
    * **Filter by Source**: `source contains "vapi-platform"`

    **Verify Event Processing:**

    1. Check that events appear in the Event Debugger shortly after sending
    2. Verify the event payload matches what you sent
    3. Confirm the `external_customer_id` matches your customer
    4. Ensure `event_name` matches your feature configuration exactly
    5. Check that `properties` contain the correct aggregation field values

    For comprehensive information on event debugging, see [Event Debugger](/docs/event-ingestion/event-debugger) and [Validating Events](/docs/event-ingestion/validating-events).
  </Step>
</Steps>

## Next Steps

After completing the setup:

1. **Monitor Usage**: Regularly check the Event Debugger to ensure events are being processed
2. **Review Invoices**: Check upcoming invoices to verify billing calculations
3. **Track Usage**: Use the Query tool to view aggregated usage by customer and feature
4. **Scale**: Add more customers and subscriptions as your business grows

For troubleshooting, see [Troubleshooting Events](/docs/event-ingestion/troubleshooting).