Claude Message Token Counting

This endpoint is used to accurately calculate and estimate the number of input tokens sent to Claude models before making a real inference request. This helps users control costs, optimize prompts, and avoid exceeding model window limits.

🌟 Endpoint Highlights

• 100% Free: Calling this token counting endpoint does not consume any account credits or subscription package quotas, and you can invoke it even if your account balance is 0.
• Multimodal Support: Perfectly supports system prompts, tools definitions, text, and image inputs (both URL and Base64 formats).
• Extreme Reliability: Features a built-in regional fallback mechanism. Even for custom ARNs or cross-region profiles that do not natively support the bedrock-runtime CountTokens, it automatically translates and returns a 100% mathematically correct token count.

Endpoint Definition

• Method: POST
• Request URL: https://easyrouter.io/v1/messages/count_tokens
• Headers:
  • Authorization: Bearer sk-your-token (Your EasyRouter API Key)
  • Content-Type: application/json

Request Parameters

The request payload format is identical to the standard Claude Messages API.

Response Parameters

Returns a standard JSON object:

• input_tokens (integer): The total number of calculated input tokens.

Request Examples

Example 1: Text-only with System Prompts

curl -X POST https://easyrouter.io/v1/messages/count_tokens \
  -H "Authorization: Bearer sk-your-token" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-6",
    "system": "You are a professional system architect.",
    "messages": [
        {
            "role": "user",
            "content": "How to design a high-availability cache layer?"
        }
    ]
  }'

Example Response:

{
  "input_tokens": 32
}

Example 2: Multimodal Request with Images

This endpoint automatically downloads and converts image inputs to calculate their precise token weight.

curl -X POST https://easyrouter.io/v1/messages/count_tokens \
  -H "Authorization: Bearer sk-your-token" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-6",
    "messages": [
        {
            "role": "user",
            "content": [
                {
                    "type": "text",
                    "text": "Identify the content of this image."
                },
                {
                    "type": "image",
                    "source": {
                        "type": "url",
                        "url": "https://easyrouter.io/logo.png"
                    }
                }
            ]
        }
    ]
  }'

Example Response:

{
  "input_tokens": 542
}