API Overview

Accessing the API

All API endpoints are available at https://api.thesys.dev/v1.

Authentication

Authentication is done via API keys. You can create API keys from the keys page. API keys must be sent as a Authorization header with the value Bearer <api_key>. If the API key is not valid, you will receive a 403 error.

Rate Limits

Please refer to the Rate Limits page for more information.

Errors

Please refer to the Errors page for more information.

Examples

python

from openai import OpenAI
client = OpenAI(
    base_url="https://api.thesys.dev/v1/embed",
    api_key="<api_key>"
)

completion = client.chat.completions.create(
    model="c1/anthropic/claude-sonnet-4/v-20250930",
    messages=[
        {
            "role": "user",
            "content": "How did the population of the world grow from 1950 to 2020?"
    }
])

Stream this response via the language specific helper functions to the react client.

Supported API Parameters

Property	C1 OpenAI models	C1 Anthropic Models
messages	(audio not supported)	(audio not supported)
model
audio
frequency_penalty
function_call	use tool_choice	use tool_choice
functions	use tools	use tools
logit_bias
logprobs
max_completion_tokens
max_tokens
metadata	thesys metadata only	thesys metadata only
modalities
n	must be 1	must be 1
parallel_tool_calls	true by default	true by default
prediction
presence_penalty
prompt_cache_key
reasoning_effort
response_format
service_tier
stop
stream
temperature
tool_choice
tools
top_p
verbosity
web_search_options