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

# Custom LLM Tracing

> Learn what it means to capture custom LLM traces

Lytix supports capturing custom LLM traces (e.g. not associated with any SDK or API call). This is useful if you have custom models you'd still like to track.

<CodeGroup>
  ```py Python
  from lytix_py import lytix


  @lytix.trace(modelName="nodeCli")
  async def getResponse(logger):
      modelOutput = "Paris is the capital of France"

      # Set our defined params however we want
      lytix.setMessage("Some user input", "user")
      lytix.setMessage(modelOutput, "assistant")

      # Optional values
      lytix.setUserIdentifier("testUser")
      lytix.setSessionId("testSession")

      return modelOutput
  ```

  ```js Typescript
  import { MetricCollector } from "@lytix/node-cli";

  const response = await MetricCollector.captureModelTrace({
    modelName: "testModelName",
    systemPrompt: "You are a helpful assistant",
    userPrompt: "Some user input",
    generateModelOutput: async () => {
      const openai = new OpenAI();
      ...
      /**
       * This callback is expecting the model output to be returned
       */
      return response;
    }
  });
  ```
</CodeGroup>