Detect page changes API

Fetch a public page and compare its Markdown with a caller-supplied previous snapshot. The snapshot is not stored. The result lists added and removed lines and does not rank their importance.

The Detect page changes operation is part of the Web & Page Intelligence API on BRAINIAC.software. Fetch a public page and compare its Markdown with a caller-supplied previous snapshot. The snapshot is not stored. The result lists added and removed lines and does not rank their importance. It is exposed as POST /api/v1/web-intelligence/page-change-detect and priced at $0.05 USDC on Base. Payment uses the x402 exact scheme: an unpaid call returns HTTP 402 with payment requirements; after paying the exact USDC amount, retry the same request with a payment-signature header and Idempotency-Key. No account and no API key are required. Data sources for this product: The public http or https URL supplied in the request. A caller-supplied previous Markdown snapshot for change detection. Limitations: Only public http and https URLs on ports 80 and 443 are fetched. Local, private, and link-local addresses are refused, including after redirects and DNS resolution. JavaScript is not executed, so client-rendered text is absent. Login, paywall, and CAPTCHA walls are not bypassed. A null field means the value was not present in the fetched document. Change detection uses the caller-supplied snapshot and does not store it. Sitemap page URLs are listed, not fetched. Outputs are compliance prechecks, drafts, or data lookups for human review. They are not official determinations, legal advice, identity confirmation, or certified filings. Related operations in this group include Convert URL to Markdown, Extract structured page data, Extract website metadata, Extract website contacts. Open the group documentation for the full request schema, field notes, and response examples before integrating.