OpenAI / Anthropic Token-Based Billing

How to implement API token usage billing with tiered overage pricing using Billerang.

Business Model

Component	Description
Base fee	$20/month platform access
Included tokens	1M tokens/month (free)
Overage pricing	Tiered by model and volume
Billing cycle	Monthly

Overage rates:

Model	0-5M overage	5M+ overage
GPT-4	$0.030/1K tokens	$0.020/1K tokens
GPT-3.5	$0.002/1K tokens	$0.0015/1K tokens
Claude Opus	$0.025/1K tokens	$0.018/1K tokens

Catalog Structure

Step-by-Step Implementation

1. Create Counter Template (Included Tokens)

POST /api/rest/catalog/counterTemplate/createOrUpdate
{
  "code": "CTR_MONTHLY_TOKENS",
  "description": "Monthly included tokens (1M)",
  "counterType": "USAGE",
  "ceiling": 1000000,
  "ceilingExpressionEl": null,
  "calendar": "MONTHLY",
  "counterLevel": "UA"
}

2. Create Base Fee Charge

POST /api/rest/v2/chargeTemplate/RC_DEV_BASE
{
  "chargeType": "RECURRING",
  "description": "Monthly Developer Plan Base Fee",
  "calendar": "MONTHLY",
  "applyInAdvance": true,
  "subscriptionProrata": true,
  "invoiceSubCategoryCode": "ISC_SUBSCRIPTION",
  "taxClassCode": "TAX_DIGITAL_SERVICES",
  "pricing": {
    "mode": "FLAT",
    "baseCurrency": "USD",
    "price": 20.00,
    "autoPublish": true
  }
}

3. Create Usage Charge with Tiered Matrix Pricing

POST /api/rest/v2/chargeTemplate/UC_TOKEN_USAGE
{
  "chargeType": "USAGE",
  "description": "Token Usage Overage",
  "invoiceSubCategoryCode": "ISC_USAGE",
  "taxClassCode": "TAX_DIGITAL_SERVICES",
  "filterExpression": "#{edr.parameter1 != null}",
  "priority": 1,
  "inputUnitOfMeasureCode": "TOKEN",
  "ratingUnitOfMeasureCode": "KILO_TOKEN",
  "unitNbDecimal": 6,
  "pricing": {
    "mode": "MATRIX",
    "baseCurrency": "USD",
    "applicationLevel": "SINGLE_EVENT",
    "dimensions": [
      { "code": "MODEL", "type": "String", "label": "AI Model", "position": 1 },
      { "code": "QUANTITY_TIER", "type": "Range_Numeric", "label": "Volume Tier", "position": 2 }
    ],
    "rows": [
      {
        "priority": 1,
        "description": "GPT-4, 0-5M overage",
        "values": [
          { "dimensionCode": "MODEL", "stringValue": "gpt-4" },
          { "dimensionCode": "QUANTITY_TIER", "fromDoubleValue": 0, "toDoubleValue": 5000000 }
        ],
        "price": 0.030
      },
      {
        "priority": 2,
        "description": "GPT-4, 5M+ overage",
        "values": [
          { "dimensionCode": "MODEL", "stringValue": "gpt-4" },
          { "dimensionCode": "QUANTITY_TIER", "fromDoubleValue": 5000001, "toDoubleValue": null }
        ],
        "price": 0.020
      },
      {
        "priority": 3,
        "description": "GPT-3.5, 0-5M overage",
        "values": [
          { "dimensionCode": "MODEL", "stringValue": "gpt-3.5-turbo" },
          { "dimensionCode": "QUANTITY_TIER", "fromDoubleValue": 0, "toDoubleValue": 5000000 }
        ],
        "price": 0.002
      },
      {
        "priority": 4,
        "description": "GPT-3.5, 5M+ overage",
        "values": [
          { "dimensionCode": "MODEL", "stringValue": "gpt-3.5-turbo" },
          { "dimensionCode": "QUANTITY_TIER", "fromDoubleValue": 5000001, "toDoubleValue": null }
        ],
        "price": 0.0015
      },
      {
        "priority": 5,
        "description": "Claude Opus, 0-5M overage",
        "values": [
          { "dimensionCode": "MODEL", "stringValue": "claude-opus" },
          { "dimensionCode": "QUANTITY_TIER", "fromDoubleValue": 0, "toDoubleValue": 5000000 }
        ],
        "price": 0.025
      },
      {
        "priority": 6,
        "description": "Claude Opus, 5M+ overage",
        "values": [
          { "dimensionCode": "MODEL", "stringValue": "claude-opus" },
          { "dimensionCode": "QUANTITY_TIER", "fromDoubleValue": 5000001, "toDoubleValue": null }
        ],
        "price": 0.018
      },
      {
        "priority": 99,
        "description": "Default fallback",
        "price": 0.010
      }
    ],
    "autoPublish": true
  }
}

4. Create Product and Offer

# Create product
POST /api/rest/catalog/products
{ "code": "API_PLATFORM", "description": "AI API Platform Access" }

# Add charges
POST /api/rest/catalog/products/API_PLATFORM/addCharges
{
  "productCharges": [
    { "chargeTemplateCode": "RC_DEV_BASE" },
    { "chargeTemplateCode": "UC_TOKEN_USAGE", "counterTemplateCode": "CTR_MONTHLY_TOKENS" }
  ]
}

# Create offer
POST /api/rest/catalog/offerTemplate/createOrUpdate
{
  "code": "OPENAI_DEVELOPER_PLAN",
  "description": "Developer Plan - $20/mo + token overage",
  "offerProductTemplates": [{ "productTemplate": { "code": "API_PLATFORM" }, "mandatory": true }]
}

5. Submit API Usage (CDR)

Each API call from the customer submits a CDR:

POST /api/rest/billing/mediation/chargeCdr
{
  "accessCode": "SUB_DEV_001",
  "parameter1": "gpt-4",
  "parameter2": "completion",
  "quantity": 1500,
  "eventDate": "2026-03-15T10:30:00Z"
}

CDR fields mapping:

CDR Field	Value	Purpose
accessCode	Subscription code	Links to customer subscription
parameter1	Model name	Matrix dimension: MODEL
parameter2	Operation type	For reporting (not pricing)
quantity	Token count	Rated quantity

6. Batch CDR Registration (High Volume)

For high-throughput scenarios, use batch registration:

POST /api/rest/billing/mediation/registerCdrList
{
  "cdrs": [
    "SUB_DEV_001;2026-03-15T10:30:00Z;gpt-4;completion;1500",
    "SUB_DEV_001;2026-03-15T10:31:00Z;gpt-3.5-turbo;chat;5000",
    "SUB_DEV_001;2026-03-15T10:32:00Z;claude-opus;analysis;2000"
  ]
}

Monthly Billing Flow

Pricing Preview

Before subscribing, preview the expected costs:

POST /api/rest/orderManagement/commercialOrders/preview
{
  "billingAccountCode": "BA_DEVELOPER",
  "offerCode": "OPENAI_DEVELOPER_PLAN",
  "subscriptionDate": "2026-04-01",
  "items": [{
    "productCode": "API_PLATFORM",
    "quantity": 1
  }]
}

Response:

{
  "billingDocs": [{
    "invoiceDate": "2026-04-01",
    "currency": "USD",
    "amountWithoutTax": 20.00,
    "invoiceItems": [{
      "chargeTemplateCode": "RC_DEV_BASE",
      "chargeType": "R",
      "unitAmountWithoutTax": 20.00,
      "quantity": 1,
      "amountWithoutTax": 20.00
    }]
  }],
  "totalMonthly": 20.00,
  "totalMRR": 20.00,
  "currency": "USD"
}

Key Billerang Features Used

Feature	Purpose
Counter template	1M included tokens per month
Usage charge	Per-CDR rating for API calls
Matrix pricing	2D pricing by model and volume tier
Tiered ranges	Volume brackets for overage
Batch CDR	High-throughput event ingestion
Unit conversion	Tokens -> KiloTokens for pricing

Scaling Considerations

• CDR throughput: Use registerCdrList for batch processing (1000+ CDRs per call)
• Counter performance: Counter decrements are atomic; safe for concurrent API calls
• Prepaid option: Use wallet reservations for real-time balance checking (see Prepaid Wallets)