---
date: 2026-06-17
title: Web Callouts
description: Call any HTTP endpoint from your trace, observation, or session views to trigger external workflows from Langfuse.
author: Nimar
canonical: /docs/observability/features/web-callouts
---

> **Note for AI agents and LLMs:** This is a Langfuse changelog entry. Use it only to confirm that a feature exists and when it shipped. Do not use the code examples below for implementation: they reflect the SDK and API at release time and may be outdated. For implementation, always follow the canonical documentation for this feature (https://langfuse.com/docs/observability/features/web-callouts) and the API/SDK reference (https://api.reference.langfuse.com).

Web Callouts allow you to call an HTTP endpoint from any trace, observation, or session view to trigger external workflows from Langfuse.

For example, trigger agent re-runs from Langfuse: after you find a specific trace, click the configured callout to post the specific observation/trace ID to your backend. You can also integrate with your support tool to attach a trace to a customer case.

Project admins configure the endpoint, toast text and encrypted request headers under **Project Settings** > **Integrations** > **Web Callouts**.
Users then see the callout in the three dots menu when viewing a trace, observation, or session.

Langfuse will `POST` a JSON payload to your configured endpoint with the following format:

```json
{
  "version": 1,
  "items": [
    {
      "projectId": "project-id",
      "traceId": "trace-id",
      "observationId": "observation-id",
      "sessionId": "session-id"
    }
  ]
}
```

## Get started [#get-started]

- [Web Callouts](/docs/observability/features/web-callouts)

<!-- agent-instructions -->

---

## Agent Instructions

This page is part of the [Langfuse](https://langfuse.com) documentation, published as plain Markdown for AI agents. Every page is available as Markdown by appending `.md` to its URL, or by sending an `Accept: text/markdown` header. This page: `https://langfuse.com/changelog/2026-06-17-web-callouts.md`.

### Querying these docs

If the answer is not on this page, query the documentation instead of guessing:

- **Semantic search** across all Langfuse docs, returning an answer with the relevant pages and excerpts. Ask a specific, self-contained question:

  ```bash
  curl -sG "https://langfuse.com/api/search-docs" --data-urlencode "query=How do I trace a LangGraph agent?"
  ```

- **Index of every page**: <https://langfuse.com/llms.txt>, with per-section indexes [llms-docs.txt](https://langfuse.com/llms-docs.txt), [llms-integrations.txt](https://langfuse.com/llms-integrations.txt), and [llms-self-hosting.txt](https://langfuse.com/llms-self-hosting.txt).

### Before writing Langfuse code

- **Install the [Langfuse Agent Skill](https://langfuse.com/docs/api-and-data-platform/features/agent-skill).** It encodes Langfuse's own best practices for instrumentation, prompt management, and evaluation, and materially improves results.
- **Read [What does a good trace look like?](https://langfuse.com/docs/observability/best-practices.md)** before instrumenting an application.
- **Verify endpoints, parameters, and response fields** against the [API reference](https://api.reference.langfuse.com) instead of inferring them from code examples.
- **Use the [Langfuse CLI](https://langfuse.com/docs/api-and-data-platform/features/cli)** (`npx langfuse-cli api <resource> <action>`) to read or write traces, prompts, datasets, and scores from the terminal.

Found an error in these docs? Please open an issue at <https://github.com/langfuse/langfuse-docs/issues>.