docs / change-detect

Change-Detect API

base /change-detect/v15 endpoints

post/change-detect/v1/snapshot1 credit

Fetch a URL and return a noise-resistant fingerprint: content_hash (normalised main content, rotating-token-stripped), structural_hash (DOM skeleton), text_hash, title, meta_description, main_content (boilerplate-stripped), word_count, links[]. Store the returned snapshot/hash and feed it back to diff/monitor_check later.

Parameter		Allowed / range	Description
url	required	—	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.
selector	optional	—	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.
follow_redirects = true	optional	—	Follow redirects (http→https, apex→www) before fingerprinting the final URL (default true). Each hop is independently SSRF-validated.

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post/change-detect/v1/diff1 credit

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.

Parameter		Allowed / range	Description
url	required	—	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.
baseline	optional	—	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`.)
url2	optional	—	Second URL — when comparing two live pages (A vs B) instead of a page against a stored baseline. SSRF-guarded like `url`.
selector	optional	—	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.
mode = text	optional	text · structural · full · links	What to compare: text (main content, default) \| structural (DOM skeleton) \| full (both) \| links (outbound link set).
follow_redirects = true	optional	—	Follow redirects (http→https, apex→www) before fingerprinting the final URL (default true). Each hop is independently SSRF-validated.

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post/change-detect/v1/monitor_check1 credit

The stateless half of monitoring: re-fetch the URL and tell you FAST whether it changed since a known hash. Pass baseline_hash (+ optional selector/mode). Returns changed(bool) + current_hash + a short diff_summary — the cheap 'did it change?' path.

Parameter		Allowed / range	Description
url	required	—	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.
baseline_hash	required	—	The content_hash (or text_hash) from a prior snapshot. monitor_check re-fetches the URL and tells you, fast, whether it changed since this hash. 64-hex.
selector	optional	—	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.
mode = text	optional	text · structural · full · links	What to compare: text (main content, default) \| structural (DOM skeleton) \| full (both) \| links (outbound link set).
follow_redirects = true	optional	—	Follow redirects (http→https, apex→www) before fingerprinting the final URL (default true). Each hop is independently SSRF-validated.

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post/change-detect/v1/extract1 credit

Main-content extraction only — boilerplate (nav/header/footer/ads/cookie/comments) stripped → clean text + structured blocks + links. Useful to feed clean diffs or to get just the article. No fingerprint comparison.

Parameter		Allowed / range	Description
url	required	—	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.
selector	optional	—	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.
follow_redirects = true	optional	—	Follow redirects (http→https, apex→www) before fingerprinting the final URL (default true). Each hop is independently SSRF-validated.

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post/change-detect/v1/batch1 credit

Snapshot up to 20 URLs concurrently in one call (each independently SSRF-guarded, shared concurrency). Returns a compact fingerprint per URL.

Parameter		Allowed / range	Description
urls	required	—	List of URLs to snapshot in one call (max 20); each is independently SSRF-guarded and fetched concurrently.
selector	optional	—	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.

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Example request · snapshot

curl -X POST https://api.reefapi.com/change-detect/v1/snapshot \
  -H "x-api-key: $REEF_KEY" \
  -H "content-type: application/json" \
  -d '{"url":"https://example.com"}'

Response shape

{
  "ok": true,
  "data": { /* the result */ },
  "meta": {
    "latency_ms": 240,
    "record_count": 12,
    "completeness_pct": 100
  },
  "error": null
}