# Rate Limit & Isolation

## Concurrency Limit

For each account, the concurrency limits for different DeepSeek API models are shown in the table below.

**If you need higher concurrency, you can submit a [capacity expansion request](https://trtgsjkv6r.feishu.cn/share/base/form/shrcnda9jNKvhyYr8xb843xLEzc). We will match the appropriate concurrency based on your actual business needs. There is no additional cost for capacity expansion.**

|                   | deepseek-flash | deepseek-v4-pro |
| ----------------- | -------------- | --------------- |
| Concurrency Limit | 2500           | 500             |

- A request counts as one concurrent connection from the time it is sent until the model response is complete
- Concurrency limits are calculated at the account level, regardless of which API Key is used
- For a given account, API requests within the concurrency limit will receive a response; when the concurrency limit is exceeded, you will receive an HTTP 429 error code

***

## user\_id Isolation

You can pass the `user_id` parameter to the API to achieve fine-grained management of different users on your business side under the same account. The specific functions of `user_id` are as follows:

- **Content Safety Isolation:** `user_id` is used to distinguish user identities on your business side for content safety handling
- **KVCache Isolation:** `user_id` is used to isolate KVCache for users on your business side for privacy management
- **Scheduling Isolation:** `user_id` is used for scheduling isolation of users on your business side
  - For regular API users, all `user_id` values are combined for concurrency limit calculation
  - For API users with increased concurrency quotas, we will limit the total concurrency under your account, and we will also impose concurrency limits on each `user_id` you pass (an empty id is treated as a special `user_id`). For each `user_id`, the concurrency limit for `deepseek-flash` is 2500, and for `deepseek-v4-pro` it is 500. If a `user_id` exceeds its limit, requests with that `user_id` under your account will receive an HTTP 429 error code

### Setting user\_id

The `user_id` parameter is a string. We recommend using only ASCII letters, digits, underscores (`_`), and hyphens (`-`). The UTF-8 encoded value must not exceed 512 bytes. Do not include user privacy information in `user_id`.

You can set the `user_id` parameter in the following ways:

#### OpenAI Chat Completions API

HTTP request body:

```json
{
    "model": "deepseek-flash",
    "messages": [{"role": "user", "content": "Hello!"}],
    "user_id": "your_user_id"
}
```

If you are using the OpenAI SDK, you need to place the `user_id` parameter under the `extra_body` parameter:

```python
response = client.chat.completions.create(
    model="deepseek-flash",
    messages=[{"role": "user", "content": "Hello!"}],
    extra_body={"user_id": "your_user_id"},
)
```

#### Anthropic API

HTTP request body:

```json
{
    "model": "deepseek-flash",
    "messages": [{"role": "user", "content": "Hello!"}],
    "metadata": {"user_id": "your_user_id"},
    "max_tokens": 1024
}
```

If you are using the Anthropic SDK, the calling method is as follows:

```python
message = client.messages.create(
    model="deepseek-flash",
    messages=[{"role": "user", "type": "text", "content": "Hello!"}],
    metadata={"user_id": "your_user_id"},
    max_tokens=1024,
)
```

***

## Request Keep-Alive Mechanism

After your request is sent, it may sometimes take a while to receive a response from the server. During this period, your HTTP request will remain connected, and you may continuously receive contents in the following formats:

- Non-streaming requests: Continuously return empty lines
- Streaming requests: Continuously return SSE keep-alive comments (`: keep-alive`)

These contents do not affect the parsing of the JSON body of the response. If you are parsing the HTTP responses yourself, please ensure to handle these empty lines or comments appropriately.

If the request has not started inference after 10 minutes, the server will close the connection.