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

  id: 1
  data: {"id":"chatcmpl-1743157601318-pzx9ougakm","object":"chat.completion.chunk","created":1743157601,"model":"c1/anthropic/claude-sonnet-4/v-20250617","choices":[{"index":0,"delta":{"role":"assistant","content":{...}}]}

  id: 2
  data: {"id":"chatcmpl-1743157601318-pzx9ougakm","object":"chat.completion.chunk","created":1743157601,"model":"c1/anthropic/claude-sonnet-4/v-20250617","choices":[{"index":0,"delta":{"content":{...}}]}
Streaming message chunks are returned by the API when stream=true 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 true for streaming.
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", "stream": true, "messages": [{"role": "user", "content": "Hello, world!"}]}' \
  https://api.thesys.dev/v1/embed/chat/completions

  id: 1
  data: {"id":"chatcmpl-1743157601318-pzx9ougakm","object":"chat.completion.chunk","created":1743157601,"model":"c1/anthropic/claude-sonnet-4/v-20250617","choices":[{"index":0,"delta":{"role":"assistant","content":{...}}]}

  id: 2
  data: {"id":"chatcmpl-1743157601318-pzx9ougakm","object":"chat.completion.chunk","created":1743157601,"model":"c1/anthropic/claude-sonnet-4/v-20250617","choices":[{"index":0,"delta":{"content":{...}}]}

​
SSE Event Stream

​
id
string
A identifier for this event.
​
data
object
One of the following objects:

​
Completion Chunk

​
id
string
required
A unique identifier for the UI completion. Will be the same in all events for a given completion.
​
object
string
required
The object type, which is always chat.completion.chunk
​
created
integer
required
Timestamp for when the chunk was created.
​
model
string
required
The model used to generate the UI completion.
​
usage
object
An object containing the usage statistics for the UI completion Only present if the generation is complete.
​
choices
array
An array of completions. Will always contain exactly one object.