---
title: "Create span iframe"
method: POST
path: "/v1/span_iframe"
tags: ["SpanIframes"]
---

# Create span iframe

`POST /v1/span_iframe`

## Request

- Base URL: `https://api.braintrust.dev`
- URL: `https://api.braintrust.dev/v1/span_iframe`
- Auth: one of:
  - HTTP bearer
  - none

Create a new span iframe. If there is an existing span iframe with the same name as the one specified in the request, will return the existing span iframe unmodified

## Request body

- CreateSpanIFrame
  - `project_id` string, uuid, required: Unique identifier for the project that the span iframe belongs under
  - `name` string, required: Name of the span iframe
  - `description` string, nullable: Textual description of the span iframe
  - `url` string, required: URL to embed the project viewer in an iframe
  - `post_message` boolean, nullable: Whether to post messages to the iframe containing the span's data. This is useful when you want to render more data than fits in the URL.

## Response `200`

Returns the new span iframe object

- SpanIFrame
  - `id` string, uuid, required: Unique identifier for the span iframe
  - `project_id` string, uuid, required: Unique identifier for the project that the span iframe belongs under
  - `user_id` string, uuid, nullable: Identifies the user who created the span iframe
  - `created` string, date-time, nullable: Date of span iframe creation
  - `deleted_at` string, date-time, nullable: Date of span iframe deletion, or null if the span iframe is still active
  - `name` string, required: Name of the span iframe
  - `description` string, nullable: Textual description of the span iframe
  - `url` string, required: URL to embed the project viewer in an iframe
  - `post_message` boolean, nullable: Whether to post messages to the iframe containing the span's data. This is useful when you want to render more data than fits in the URL.

## Other responses

- `400`: The request was unacceptable, often due to missing a required parameter
- `401`: No valid API key provided
- `403`: The API key doesn’t have permissions to perform the request
- `429`: Too many requests hit the API too quickly. We recommend an exponential backoff of your requests
- `500`: Something went wrong on Braintrust's end. (These are rare.)

## Changes

- **2026-10-30** `8f5039399f77`: 2 breaking
  - the request property `description` became not nullable
  - the request property `post_message` became not nullable
- **2026-09-03** `ebac33c1422e`: 1 breaking
  - request body became required
- **2025-06-17** `77a2d5797d94`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/braintrustdata/apis/braintrust-api/changes/v1/span_iframe/post.md)

---

[API](https://skmtc.dev/braintrustdata/apis/braintrust-api.md) - [All operations](https://skmtc.dev/braintrustdata/apis/braintrust-api/llms.txt) - [OpenAPI document](https://skmtc.dev/braintrustdata/apis/braintrust-api/revisions/19184ec94018?raw)