Apertis Docs

Text Generation

Chat Completion

Generate a model response for a conversation with the OpenAI-compatible POST /v1/chat/completions endpoint.

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/v1/chat/completions

HTTP Request

cURL

curl https://api.apertis.ai/v1/chat/completions \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer <APERTIS_API_KEY>" \
    -d '{
        "model": "<MODEL_ALIAS>",
        "messages": [
            {
                "role": "system",
                "content": "<MESSAGES>"
            }
        ]
    }'

Python

from openai import OpenAI

client = OpenAI(
    api_key="<APERTIS_API_KEY>",
    base_url="https://api.apertis.ai/v1"
)

response = client.chat.completions.create(
    model="<MODEL_ALIAS>",
    messages=[
        {
            "role": "system",
            "content": "<MESSAGES>"
        }
    ]
)

print(response.choices[0].message.content)

JavaScript

import OpenAI from 'openai';

const client = new OpenAI({
  apiKey: '<APERTIS_API_KEY>',
  baseURL: 'https://api.apertis.ai/v1'
});

const response = await client.chat.completions.create({
  model: '<MODEL_ALIAS>',
  messages: [
    {
      role: 'system',
      content: '<MESSAGES>'
    }
  ]
});

console.log(response.choices[0].message.content);
  • <APERTIS_API_KEY>: Your API key
  • <MODEL_ALIAS>: The alias of the model to use
  • <MESSAGES>: The messages to send to the model

Optional Headers

Header Type Description
X-Timeout integer Total request timeout in milliseconds. Caps the entire request lifecycle including all channel retries. Range: 5,000–300,000 ms. Default: 60,000 ms (60s). See Request Timeout.

Optional Parameters

Parameter Type Description
temperature number Sampling temperature (0-2). Default: 1
max_tokens integer Maximum tokens in the response
top_p number Nucleus sampling threshold (0-1)
stream boolean Enable streaming. Default: false
compression object Context compression configuration

Context Compression

Add a compression object to automatically summarize older conversation history and reduce token usage for long conversations:

cURL

curl https://api.apertis.ai/v1/chat/completions \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer <APERTIS_API_KEY>" \
    -d '{
        "model": "gemini-3-flash-preview",
        "messages": [{"role": "user", "content": "Hello!"}],
        "compression": {"enabled": true, "model": "gemini-3-flash-preview"}
    }'

Python

from openai import OpenAI

client = OpenAI(
    api_key="<APERTIS_API_KEY>",
    base_url="https://api.apertis.ai/v1"
)

response = client.chat.completions.create(
    model="gemini-3-flash-preview",
    messages=[{"role": "user", "content": "Hello!"}],
    extra_body={"compression": {"enabled": True, "model": "gemini-3-flash-preview"}}
)

JavaScript

import OpenAI from 'openai';

const client = new OpenAI({
  apiKey: '<APERTIS_API_KEY>',
  baseURL: 'https://api.apertis.ai/v1'
});

const response = await client.chat.completions.create({
  model: 'gemini-3-flash-preview',
  messages: [{ role: 'user', content: 'Hello!' }],
  compression: { enabled: true, model: 'gemini-3-flash-preview' }
});

See Context Compression for full documentation.

Request Timeout

Use the X-Timeout header to limit the total time a request can take, including all internal channel retries. This prevents long waits when multiple upstream providers are slow or unavailable.

cURL

curl https://api.apertis.ai/v1/chat/completions \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer <APERTIS_API_KEY>" \
    -H "X-Timeout: 20000" \
    -d '{
        "model": "gemini-3-flash-preview",
        "messages": [{"role": "user", "content": "Hello!"}]
    }'

Python

from openai import OpenAI

client = OpenAI(
    api_key="your-apertis-key",
    base_url="https://api.apertis.ai/v1"
)

response = client.chat.completions.create(
    model="gemini-3-flash-preview",
    messages=[{"role": "user", "content": "Hello!"}],
    extra_headers={"X-Timeout": "20000"}  # 20 seconds
)

JavaScript

import OpenAI from 'openai';

const client = new OpenAI({
  apiKey: 'your-apertis-key',
  baseURL: 'https://api.apertis.ai/v1'
});

const response = await client.chat.completions.create(
  {
    model: 'gemini-3-flash-preview',
    messages: [{ role: 'user', content: 'Hello!' }]
  },
  { headers: { 'X-Timeout': '20000' } } // 20 seconds
);
Setting Value
Default 60,000 ms (60 seconds)
Minimum 5,000 ms (5 seconds)
Maximum 300,000 ms (5 minutes)

When the timeout is exceeded, the API returns HTTP 408 with diagnostic headers:

Header Description
X-Timeout-Attempts Number of upstream channels attempted
X-Timeout-Elapsed-Ms Actual elapsed time in milliseconds 
{
  "error": {
    "message": "Total request timeout (20000ms) exceeded after 3 channel attempts. Set X-Timeout header to adjust.",
    "type": "timeout",
    "code": "request_timeout"
  }
}

See also: Fallback Models for per-model fallback timeout configuration.