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Python Quickstart

Sign your first AI output in 60 seconds

From Python. Pure requests — no SDK install needed. Multi-model. Designed for admissibility under FRE 902(13)/(14) self-authenticating digital evidence.

1. Get your API key

Sign up at certnode.io/sign-up if you don't have an account. Then create an API key from the dashboard. Free tier gives you 100 signings/month, no card required.

Get API key →

2. Set the API key in your environment

export CERTNODE_API_KEY=cn_live_…

3. Sign an AI output

Save this as sign.py and run it:

import os
import requests

API_KEY = os.environ['CERTNODE_API_KEY']

response = requests.post(
    'https://certnode.io/api/v1/provenance/sign',
    headers={
        'Authorization': f'Bearer {API_KEY}',
        'Content-Type': 'application/json',
    },
    json={
        'content': 'Hello from your AI model',
        'model': 'claude-opus-4-7',
        'contentType': 'ai_output',
    },
)
receipt = response.json()

print('Receipt ID:', receipt['receiptId'])
print('Verify URL:', receipt['verifyUrl'])
print('Timestamps:', receipt['timestamps'])  # CertNode + RFC 3161 + Bitcoin OTS chain
python sign.py

4. Verify the receipt

Open the verify URL in a browser. Anyone with the URL can verify the three-layer chain — no authentication needed. Verifications are always free.

Common patterns

AI training data provenance. Sign each labeled record at ingestion time. Stable receipt URL becomes the audit trail for EU AI Act Article 50 compliance.

LLM output for litigation defense. Sign every AI-assisted document at generation. Foundation cost in court drops from days of expert testimony to a one-paragraph FRE 902(13)/(14) certification.

Compliance audit logs. Sign each AI-mediated decision your system makes (loan approvals, healthcare triage, legal drafting). The receipt chain is independently verifiable forever.

Next steps