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Diff a page against a prior baseline (snapshot object OR content_hash OR raw text), or compare two live URLs (url + url2). Returns changed(bool), change_ratio(0..1), change_type(text|structural|both|none), added[]/removed[]/modified[] blocks, and a human summary — all on the NOISE-RESISTANT normalised content.
The page to fingerprint. Full URL (https://example.com/page) or bare domain (example.com → https:// assumed). Only http/https; private / internal / cloud-metadata targets are SSRF-blocked. Alias: target.
The prior state to diff against: a snapshot object returned by a previous `snapshot` call, OR a 64-hex content_hash, OR raw prior text/HTML. (diff needs `baseline` OR `url2`.)
Second URL — when comparing two live pages (A vs B) instead of a page against a stored baseline. SSRF-guarded like `url`.
Scope detection to a region instead of the whole page. Accepts a FULL CSS selector ('div.price-box > span.amount', '.product:nth-child(2)', '[data-testid=total]') OR an XPath ('//div[@id="price"]', '//table//tr[2]/td[3]') — lxml-backed. If the selector matches nothing the whole page is used and `selector_matched:false` is reported.
What to compare: text (main content, default) | structural (DOM skeleton) | full (both) | links (outbound link set).
Follow redirects (http→https, apex→www) before fingerprinting the final URL (default true). Each hop is independently SSRF-validated.
curl -X POST https://api.reefapi.com/change-detect/v1/diff \
-H "x-api-key: $REEF_KEY" \
-H "content-type: application/json" \
-d '{"url":"https://example.com","url2":"https://www.iana.org/help/example-domains"}'Hit Send to run this endpoint live.