Using the Responses API | DeepSeek API Docs

To meet the demand for Codex, our API now supports the Responses API format, with the base_url being https://api.deepseek.com.

With a simple configuration, you can use DeepSeek models in Codex.

Integrating DeepSeek Models into Codex​

Please refer to Integrate with Codex.

Calling DeepSeek Models via the Responses API​

# Please install OpenAI SDK first: `pip3 install openai`
from openai import OpenAI

client = OpenAI(api_key="<your DeepSeek API Key>", base_url="https://api.deepseek.com")

response = client.responses.create(
    model="deepseek-flash",
    instructions="You are a helpful assistant.",
    input="Hi, how are you?",
)

print(response.output_text)

Streaming​

Set stream: true to receive the response as a sequence of semantic server-sent events (SSE). Each event carries an event field indicating the event type, and a monotonically increasing sequence_number. The stream ends with a response.completed / response.incomplete / response.failed event — there is no data: [DONE] message.

stream = client.responses.create(
    model="deepseek-flash",
    instructions="You are a helpful assistant.",
    input="Hi, how are you?",
    stream=True,
)

for event in stream:
    if event.type == "response.output_text.delta":
        print(event.delta, end="")

The full list of events:

Image Input​

The Responses API accepts images with the deepseek-flash model. The same image limits and supported formats as Chat Completions apply.

Images are provided via an input_image content part in a message item, with either image_url (an http(s) URL or a base64 data URL) or file_id (an image uploaded via the Files API):

response = client.responses.create(
    model="deepseek-flash",
    input=[
        {
            "role": "user",
            "content": [
                {"type": "input_text", "text": "What is in this image?"},
                {"type": "input_image", "image_url": "https://example.com/image.jpg", "detail": "low"},
            ],
        }
    ],
)
print(response.output_text)

input_image parts may also appear in the output of function_call_output / custom_tool_call_output items, so the model can receive images produced by your tools:

input=[
    {"role": "user", "content": "Read the screenshot the tool returned."},
    {"type": "function_call", "call_id": "fc1", "name": "take_screenshot", "arguments": "{}"},
    {"type": "function_call_output", "call_id": "fc1",
     "output": [{"type": "input_image", "image_url": "data:image/png;base64,<BASE64_DATA>"}]},
]

input_image Fields​

• image_url: An http(s) URL (at most 8192 characters) or a base64-encoded data URL (data:image/jpeg;base64,...). Supported formats: JPEG, PNG, GIF, WebP.
• file_id: The ID of an image uploaded via the Files API, of the form file-api-....
• detail: low / high / original / auto. low downsamples the image to 512x512 before inference; the other values keep the original image. Ignored when file_id is set.

image_url and file_id are mutually exclusive: passing neither returns a 400 error ("input_image must have image_url or file_id"), and passing both returns a 400 error ("input_image cannot have both image_url and file_id").

Restrictions​

• Images are allowed only in user / developer message items and in function_call_output / custom_tool_call_output outputs. Images in system or assistant messages return a 400 error.
• deepseek-flash processes input_image parts as real images.
• The same shared image limits as Chat Completions apply (32 MiB per inline image, 64 MiB per file_id image, 64 MiB total without file_id images or up to 200 MiB with them, 600 images per request, etc.) — see Vision: Limits.

Compatibility Details​

This section lists the compatibility details of the DeepSeek API with the Responses API. For the full Responses API format definition, please refer to the official OpenAI API reference.

Top-level Request Parameters​

Unsupported parameters are silently ignored and do not cause errors, so existing Responses API clients can connect without modification.

Input Items​

Note: web_search_call items passed back in input — for example, search results produced by an earlier request with an older model — are still restored and concatenated into the context.

Tools​

Response Fields​

The response object is compatible with the OpenAI Responses API response structure. Fields that depend on unsupported capabilities always take fixed values (e.g. store: false, previous_response_id: null, parallel_tool_calls: true).

Token usage is returned in usage:

• input_tokens: number of input tokens, where input_tokens_details.cached_tokens is the number of tokens hitting the context cache
• output_tokens: number of output tokens, where output_tokens_details.reasoning_tokens is the number of chain-of-thought tokens