Chat

Given a list of messages comprising a conversation, the model will return a response.

Create Chat Completion

POST https://api.sybil.com/v1/chat/completions

Creates a model response for the given chat conversation.

Request Body

Name	Type	Description
messages	array	Required. A list of messages comprising the conversation so far.
model	string	Required. The name of the model to use.
frequency_penalty	number	Number between -2.0 and 2.0. Positive values penalize new tokens based on their existing frequency in the text so far, decreasing the model's likelihood to repeat the same line verbatim.
max_tokens	integer	The maximum number of tokens that can be generated in the chat completion.
presence_penalty	number	Number between -2.0 and 2.0. Positive values penalize new tokens based on whether they appear in the text so far, increasing the model's likelihood to talk about new topics.
response_format	object	An object specifying the format that the model must output. Setting to { "type": "json_object" } enables JSON mode.
seed	integer	If specified, our system will make a best effort to sample deterministically.
stop	string/array	Up to 4 sequences where the API will stop generating further tokens.
stream	boolean	If set, partial message deltas will be sent, like in ChatGPT. Tokens will be sent as data-only server-sent events as they become available.
temperature	number	What sampling temperature to use, between 0 and 2. Higher values like 0.8 will make the output more random, while lower values like 0.2 will make it more focused and deterministic.
top_p	number	An alternative to sampling with temperature, called nucleus sampling, where the model considers the results of the tokens with top_p probability mass. So 0.1 means only the tokens comprising the top 10% probability mass are considered.

Example Request

curl https://api.sybil.com/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $SYBIL_API_KEY" \
  -d '{
    "model": "DeepSeek-R3",
    "messages": [
      {
        "role": "system",
        "content": "You are a helpful assistant."
      },
      {
        "role": "user",
        "content": "Hello!"
      }
    ]
  }'

Response Format

{
  "model": "DeepSeek-R3",
  "system_fingerprint": "fp_44709d6fcb",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "\n\nHello there, how may I assist you today?"
      },
      "logprobs": null,
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 9,
    "completion_tokens": 12,
    "total_tokens": 21
  }
}