> ## Documentation Index
> Fetch the complete documentation index at: https://langchain-5e9cc07a-preview-devupd-1765394015-eccef47.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Callbacks

<Columns cols={3}>
  <Card title="Datadog Tracer" icon="link" href="/oss/javascript/integrations/callbacks/datadog_tracer" arrow="true" cta="View guide" />

  <Card title="Upstash Rate Limit" icon="link" href="/oss/javascript/integrations/callbacks/upstash_ratelimit_callback" arrow="true" cta="View guide" />
</Columns>

***

<Callout icon="pen-to-square" iconType="regular">
  [Edit the source of this page on GitHub.](https://github.com/langchain-ai/docs/edit/main/src/oss/javascript/integrations/callbacks/index.mdx)
</Callout>

<Tip icon="terminal" iconType="regular">
  [Connect these docs programmatically](/use-these-docs) to Claude, VSCode, and more via MCP for real-time answers.
</Tip>