curl -X POST \
  -H "Authorization: Bearer <api_key>" \
  -H "Content-Type: application/json" \
  -d '{"model": "c1/anthropic/claude-sonnet-4/v-20250617", "messages": [{"role": "user", "content": "Hello, world!"}]}' \
  https://api.thesys.dev/v1/embed/chat/completions

{
      "id": "chatcmpl-1743157633416-cffw7tgswx",
      "object": "chat.completion",
      "created": 1743157633,
      "model": "c1/anthropic/claude-sonnet-4/v-20250617",
      "choices": [
          {
          "index": 0,
          "message": {
              "role": "assistant",
              "content": {
                  ...
              }
          },
          "finish_reason": "stop"
          }
      ],
      "usage": {
          "prompt_tokens": 8,
          "completion_tokens": 439,
          "total_tokens": 447
      }
}
UI completions are returned by the API when stream=false is set in the request.

​
Request Headers

​
Authorization
string
required
The API key to use for the request.
​
Content-Type
string
required
The content type of the request. Should be application/json.

​
Request Body

​
messages
array
required
An array of messages of the conversation so far.
​
model
string
required
The model to use for the UI completion. Should be one of the models listed in the Models page.
​
temperature
number
The temperature to use for the UI completion. Should be between 0 and 1.
​
top_p
number
The top-p value to use for the UI completion. Should be between 0 and 1.
​
max_tokens
integer
The maximum number of tokens to use for the UI completion.
​
n
integer
The number of completions to generate.
​
stop
integer
Should be unset or set to 1.
​
stream
boolean
Whether to stream the response. Should be unset or false.
All other request parameters are ignored.
curl -X POST \
  -H "Authorization: Bearer <api_key>" \
  -H "Content-Type: application/json" \
  -d '{"model": "c1/anthropic/claude-sonnet-4/v-20250617", "messages": [{"role": "user", "content": "Hello, world!"}]}' \
  https://api.thesys.dev/v1/embed/chat/completions

{
      "id": "chatcmpl-1743157633416-cffw7tgswx",
      "object": "chat.completion",
      "created": 1743157633,
      "model": "c1/anthropic/claude-sonnet-4/v-20250617",
      "choices": [
          {
          "index": 0,
          "message": {
              "role": "assistant",
              "content": {
                  ...
              }
          },
          "finish_reason": "stop"
          }
      ],
      "usage": {
          "prompt_tokens": 8,
          "completion_tokens": 439,
          "total_tokens": 447
      }
}

​
Response

​
id
string
A unique identifier for the UI completion
​
choices
array
An array of completions. Will always contain exactly one object.
​
created
string
The timestamp when the UI completion was created
​
model
string
The model used to generate the UI completion
​
object
string
The object type, which is always chat.completion
​
usage
object
An object containing the usage statistics for the UI completion