Verify a quote

Last updated: 2026-10-10

POST /v1/verify/quote fetches a page and reports whether a quote appears on it: exact, fuzzy or none, with offsets, surrounding context, the page verdict and a signed receipt. For a paraphrased claim, "match": "passages" returns instead the passages that share most of its words (below). Price: US$0.01 per call.

It checks your exact words, not a reworded version, against the page and returns offsets and page hashes in a signed receipt, all in one US$0.01 call.

Use it before citing a page, to check that the words you attribute to it are on it, and that the page you got is real content rather than a bot wall or an error page.

For 9 or more quotes on one page, verify/quotes costs less: one call checks up to 20.

Request

{
  "url": "https://www.iana.org/help/example-domains",
  "quote": "These domains may be used as illustrative examples in documents",
  "match": "fuzzy",
  "case_sensitive": false,
  "threshold": 0.9
}

Before matching, both the page text and the quote are normalised: Unicode NFKC, curly quotes and dashes become plain ones, invisible characters are dropped, and all whitespace becomes one space.

Response

From the free sample (GET /v1/sample/quote), shortened:

{
  "result": {
    "match": "fuzzy",
    "score": 0.963,
    "start": 211,
    "end": 238,
    "context": "...the agency said that emissions fell 12 % in 2025, after two years of slow growth...",
    "occurrences": 1,
    "normalised_sha256": "086a29af…"
  },
  "page": {
    "requested_url": "https://vehcdj664efetfrsolne5umanq.srv.us/v1/sample/page",
    "final_url": "https://vehcdj664efetfrsolne5umanq.srv.us/v1/sample/page",
    "http_status": 200,
    "content_kind": "real",
    "signals": ["status_200"],
    "title": "Regional climate report 2025 (demo page)",
    "content_sha256": "0e429607…",
    "retrieved_at": "2026-10-09T14:19:34.903Z"
  },
  "injection_flags": [],
  "advice": "The page loaded and looks like real content.",
  "receipt": "eyJhbGciOiJFZERTQSIs…",
  "tier": "paid",
  "rail": "x402",
  "network": "eip155:84532"
}

• match is exact, fuzzy or none. score is the similarity from 0 to 1.
• start and end are code-point offsets into the normalised page text. normalised_sha256 is the SHA-256 of that text, so anyone holding the page text can check the offsets.
• occurrences counts exact matches.
• Read page.content_kind before relying on match. A none on a bot_wall or js_shell page means we could not read the page, not that the quote is absent from it. See How it works.

Passages: a paraphrased claim

An agent rarely quotes word for word. With "match": "passages", quote is a claim (for example "The agency reported a 12 percent drop in emissions during 2025") and the answer is the 3 passages of the page that share most of its words:

On the demo page ([https://vehcdj664efetfrsolne5umanq.srv.us/v1/sample/page](https://vehcdj664efetfrsolne5umanq.srv.us/v1/sample/page)), shortened; try it free with [GET /v1/sample/quote?match=passages](https://vehcdj664efetfrsolne5umanq.srv.us/v1/sample/quote?match=passages):

{
  "result": {
    "match": "passages",
    "score": 0.583,
    "start": 115,
    "end": 271,
    "occurrences": 3,
    "passages": [
      { "start": 115, "end": 271, "score": 0.583, "text": "It is not a real report and its numbers are made up. In its annual summary the agency said that emissions fell 12 % in 2025, after two years of slow growth.", "missing": ["drop"], "flags": ["negation_mismatch"] },
      { "start": 357, "end": 513, "score": 0.217, "text": "The agency also noted that the share of renewable power rose to 41 percent, and that the next report will cover water use and air quality across the region.", "missing": ["12", "drop", "emissions", "2025"], "flags": ["number_mismatch"] },
      { "start": 0, "end": 114, "score": 0.136, "text": "Regional climate report 2025 This is a demo page served by AttestPage so that agents can try every route for free.", "missing": ["agency", "12", "percent", "drop", "emissions"], "flags": [] }
    ],
    "scorer": "lexical-v2",
    "note": "Passages ranked by how many of the claim's words (weighted by rarity on the page) and word pairs they share. This is evidence for you to judge, not a verdict: ..."
  }
}

Here "reported" counted as found because the passage has "report". The best passage does support the claim, but only a reader can tell that "fell 12 %" means a 12 percent drop. It is flagged negation_mismatch only because its first sentence says "not a real report": a flag tells you where to look, not that the passage contradicts the claim.

• This is evidence, not a verdict. A score measures shared words, not meaning. "Emissions did not fall" shares as many words as "emissions fell". Read each passage, and check negation, numbers, dates and the words in missing.
• Passages. A passage is a sentence, or two neighbouring ones; text with no sentence ends is cut every 40 words. A sentence ends at ., ! or ? before a space, or at 。, ！ or ？, but not after a short abbreviation such as "e.g.", "i.e.", "Dr.", "Mr." or an initial ("J. Smith"); "etc." ends one only before a capital. Passages do not overlap and are sorted by score, highest first. The top-level score, start, end and context are those of the best passage, and occurrences counts the passages.
• Score. From 0 to 1: 0.75 × the share of the claim's words the passage holds, each weighted by how rare it is on the page, plus 0.25 × the share of the claim's neighbouring word pairs it holds.
• How words are compared. Without case, with light English stemming ("emissions" meets "emission"), and ignoring common English words such as "the" and "was". % counts as "percent". In Chinese and Japanese, each character counts as a word.
• Offsets and text. start and end are code-point offsets into the normalised page text, as above. text is cut to 800 characters with ... when the passage is longer.
• missing. Lists the claim's words that the passage lacks, at most 20.
• flags. Marks a passage worth a closer read; it never changes the score or the order. negation_mismatch: the claim or the passage has an English negation ("not", "no", "never", "n't", "without" and similar) and the other has none. number_mismatch: the claim has a number the passage lacks and the passage has one the claim lacks, such as 12 against 15 (12 %, 12 percent and 12.0 count as the same number, and so do 1,000 and 1000). An empty list does not mean the passage agrees with the claim.
• No match. match is none with an empty passages list when no passage shares a word.
• Errors. A claim made only of common words or punctuation gets 400.
• Same answer every time. No language model is used, so the same page and claim give the same answer. scorer names the method (now lexical-v2) and changes whenever the same page and claim could give different passages, scores or flags.
• Cost. The cost is linear in the page size, so passages never gets match_too_costly.
• Receipt. The receipt signs mode, scorer and each passage's start, end and score. The text can be recovered from the page at those offsets, and missing and flags from that text, the claim and the scorer.
• Price. The same as any other verify/quote call.

PDF

A PDF page is matched like any other page. Its text layer is read as described in Fetch: PDF, with no OCR.

• A match on a PDF also has pdf_page and pdf_page_end: the 1-based pages where it starts and ends. Each passage has them too.
• start and end are still offsets into the whole normalised text. In that text, each page break is one space.
• Only text inside each page's box is read, as a reader sees it. A quote from text drawn outside the page is not found.
• The receipt signs pdf_page and pdf_page_end next to the offsets.

Only the full service reads PDFs: an edge server answers 501 not_on_edge (details.reason pdf) for one, not charged. Limits are in Limits.

Charging

The quote and options are checked before payment: a bad request gets 400 and is not charged. A quote too costly to match fuzzily gets 422 match_too_costly, not charged; use "match": "exact" or a shorter quote. A URL whose host name does not resolve gets 422 host_not_found, not charged. Results about the page itself, including 404s, bot walls and timeouts, are charged. See Payments.