curl -X GET 'https://api.anthropic.com/v1/sessions/session-id/threads/thread-id/stream?beta=true&event_deltas%5B%5D=example' \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H 'anthropic-version: 2023-06-01'

# GET /v1/sessions/{session_id}/threads/{thread_id}/stream?beta=true (Claude API)
Base URL: https://api.anthropic.com
Auth: x-api-key; Anthropic API key; required.
Status: Beta.
Last verified: 2026-10-20

> Stream Session Thread Events

## Critical Gotchas
* Authentication uses the `x-api-key` header and requests also require an `anthropic-version` header.
* The official OpenAPI URL is discovered from the SDK repository manifest and must remain under Anthropic's trusted Stainless storage prefix.

## cURL
curl -X GET 'https://api.anthropic.com/v1/sessions/session-id/threads/thread-id/stream?beta=true&event_deltas%5B%5D=example' \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H 'anthropic-version: 2023-06-01'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| session_id | path | string | Yes | Path parameter session_id |
| thread_id | path | string | Yes | Path parameter thread_id |
| event_deltas[] | query | string[] | No | When set, this connection also receives streaming deltas (`event_start`, `eve... |

## Response example
{"type":"user.message","id":"sevt_011CZkZGOp0iBcp4kaQSihUmy"}

---
Need an API key? Get one at https://console.anthropic.com/settings/keys

GET

GET /v1/sessions/{session_id}/threads/{thread_id}/stream?beta=true — Claude API

Beta

Anthropic API key (required); https://api.anthropic.com

Claude API

Stream Session Thread Events

Base URL: https://api.anthropic.com
Auth: x-api-key: <ANTHROPIC_API_KEY>
Last verified: 2026-10-20 · upstream hash matched

Actions Try in browser→

Agents: curl -H "Accept: text/markdown" this URL
→ 206 tokens · Vary: Accept

Critical gotchas

Authentication uses the x-api-key header and requests also require an anthropic-version header.

The official OpenAPI URL is discovered from the SDK repository manifest and must remain under Anthropic's trusted Stainless storage prefix.

cURL

curl -X GET 'https://api.anthropic.com/v1/sessions/session-id/threads/thread-id/stream?beta=true&event_deltas%5B%5D=example' \  -H "x-api-key: $ANTHROPIC_API_KEY" \  -H 'anthropic-version: 2023-06-01'

Parameters

Name	In	Type	Required	Description
session_id	path	string	Yes	Path parameter session_id
thread_id	path	string	Yes	Path parameter thread_id
event_deltas[]	query	string[]	No	When set, this connection also receives streaming deltas (`event_start`, `event_delta`) while an event is being produced, before the event itself arrives. Deltas are best-effort; when the final event is produced it carries the complete content. A model request that ends early (an error or interrupt) produces no final event — its terminal `span.model_request_end` closes the preview. Accepts one or more event types to preview and may be repeated: `agent.message` streams `content_delta` fragments; `agent.thinking` is start-only — a signal that the agent has begun extended thinking, concluded by the `agent.thinking` event itself. Only previews of the requested event types are sent.

Response 200 OK

{
  "type": "user.message",
  "id": "sevt_011CZkZGOp0iBcp4kaQSihUmy",
  "content": [
    {
      "type": "text",
      "text": "Where is my order #1234?"
    }
  ],
  "processed_at": "2026-03-15T10:00:00Z"
}

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