Create Trace
Send a trace to the Costrace backend.
Authorization: Bearer ct_your_api_key
Content-Type: application/json
Request Body
LLM provider: openai, anthropic, or gemini
Model name (e.g., gpt-4o, claude-sonnet-4-20250514)
Number of input/prompt tokens
Number of output/completion tokens
Request latency in milliseconds
Your Costrace API key (used to identify the trace source)
Request status: success or error
Error message (only if status is error)
Example Request
curl -X POST https://api.costrace.dev/v1/traces \
-H "Authorization: Bearer ct_your_api_key" \
-H "Content-Type: application/json" \
-d '{
"provider": "openai",
"model": "gpt-4o",
"tokens_in": 100,
"tokens_out": 50,
"latency_ms": 1234,
"cost_usd": 0.005,
"api_key": "ct_your_api_key",
"status": "success"
}'
import requests
response = requests.post(
"https://api.costrace.dev/v1/traces",
headers={
"Authorization": "Bearer ct_your_api_key",
"Content-Type": "application/json",
},
json={
"provider": "openai",
"model": "gpt-4o",
"tokens_in": 100,
"tokens_out": 50,
"latency_ms": 1234,
"cost_usd": 0.005,
"api_key": "ct_your_api_key",
"status": "success",
},
)
const response = await fetch("https://api.costrace.dev/v1/traces", {
method: "POST",
headers: {
"Authorization": "Bearer ct_your_api_key",
"Content-Type": "application/json",
},
body: JSON.stringify({
provider: "openai",
model: "gpt-4o",
tokens_in: 100,
tokens_out: 50,
latency_ms: 1234,
cost_usd: 0.005,
api_key: "ct_your_api_key",
status: "success",
}),
});
Response
ok if the trace was accepted
202 Accepted
Error Responses
400 Bad Request
Invalid request body:
{
"error": "Validation error",
"details": "Missing required field: provider"
}
401 Unauthorized
Invalid API key:
{
"error": "Unauthorized",
"message": "Invalid API key"
}
Cost Calculation
The SDK automatically calculates costs based on current pricing. If you’re sending traces manually, use this formula:
cost_usd = (tokens_in / 1_000_000) * input_price_per_million +
(tokens_out / 1_000_000) * output_price_per_million
Example Pricing (as of Feb 2026)
| Provider | Model | Input ($/1M) | Output ($/1M) |
|---|
| OpenAI | gpt-4o | $2.50 | $10.00 |
| OpenAI | gpt-4o-mini | $0.15 | $0.60 |
| Anthropic | claude-opus-4-6 | $5.00 | $25.00 |
| Anthropic | claude-haiku-4-5 | $1.00 | $5.00 |
| Gemini | gemini-2.0-flash | $0.10 | $0.40 |
Pricing is subject to change by providers. The SDK includes up-to-date pricing tables.
Best Practices
Use the SDK
The SDKs handle trace creation, cost calculation, and sending automatically. Manual API calls are only needed for:
- Custom integrations
- Non-supported languages
- Debugging
Fire-and-Forget
Traces are sent asynchronously. Don’t wait for responses — they’re fire-and-forget by design.
Error Handling
Failed trace sends should not break your application. The SDK catches network errors silently.