Python quickstart

Install the SDK from the same checkout as the core:

python3 -m venv .venv
. .venv/bin/activate
pip install -e ./sdk/python
export FACT0_BASE_URL=http://localhost:8000
# Set FACT0_API_KEY to a local key created in your dashboard.
python examples/local-python.py

The published distribution is named fact0-sdk; its Python import is fact0. For a released compatible SDK, pip install fact0-sdk is also available. Always pass the self-hosted base URL explicitly; existing SDK defaults remain unchanged.

import os
from fact0 import Client

client = Client(api_key=os.environ["FACT0_API_KEY"],
                base_url=os.environ["FACT0_BASE_URL"], sync=True)
try:
    with client.telemetry.execution(agent_id="my-agent") as execution:
        with execution.span("work") as span:
            span.complete(output={"result": 42})
    client.flush()
finally:
    client.close()

The repository example includes a nested tool and a handled failure, reads the stored spans back, verifies the audit chain and saves an evidence ZIP. Open Executions and Audit in your local dashboard to inspect the result. It does not send prompts to any model service. For LangChain recipes, install pip install -e './sdk/python[langchain]'. Python, TypeScript and Go package identities are preserved; only the Python and Claude Code walkthroughs are core release acceptance gates.

Start here

Workflows

Operation

Python quickstart