Re-check a page against an earlier receipt

Last updated: 2026-10-12

POST /v1/recheck fetches the page named in an earlier receipt again and tells you whether its text changed: unchanged, changed, gone or unreadable, the fields that differ, and a signed receipt naming both the old and the new hashes. Price: US$0.003 per call.

When to use it

For page change detection without storing anything: keep the receipt, recheck when you need to know.
Before reusing a quote or a citation you checked days ago.
To keep a dated chain of evidence that a page stayed the same (each receipt names the one before).

Request

Send exactly one of the two baseline forms. The receipt from an earlier call:

{ "receipt": "eyJhbGciOiJFZERTQSIs…", "return_text": false }

Or a URL and the content_sha256 from our own fetch of it:

{ "url": "https://www.iana.org/help/example-domains", "content_sha256": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", "return_text": false }

Field	Required	Meaning
`receipt`	one of the two forms	compact JWS receipt from an earlier `/v1/fetch`, `/v1/verify/quote` or `/v1/recheck` call of this service, paid or trial (not a sample), at most 160 KB
`url`	one of the two forms	only without `receipt`: http or https URL, at most 2,048 characters
`content_sha256`	with `url`	the `page.content_sha256` from our own fetch, 64 hex characters; other tools hash other text, so their hashes will not match
`return_text`	no	also return up to 20,000 characters of the new clean text; default `false`

The page fetched is the baseline's url (the URL first asked for, not the final URL), so redirects are followed again. The body may be up to 168 KB, so a long receipt fits.

Answer

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

{
  "change": "unchanged",
  "changed": false,
  "differences": [],
  "baseline": {
    "source": "caller",
    "receipt_sha256": null,
    "url": "https://vehcdj664efetfrsolne5umanq.srv.us/v1/sample/page",
    "content_sha256": "0e429607…"
  },
  "elapsed_seconds": null,
  "page": {
    "final_url": "https://vehcdj664efetfrsolne5umanq.srv.us/v1/sample/page",
    "http_status": 200,
    "content_kind": "real",
    "content_sha256": "0e429607…",
    "raw_sha256": "179b9ac4…"
  },
  "text": null,
  "injection_flags": [],
  "advice": "The page's text is the same as in the baseline (byte for byte on the clean text). Markup or other bytes may still have moved; see differences.",
  "receipt": "eyJhbGciOiJFZERTQSIs…",
  "tier": "paid",
  "rail": "x402",
  "network": "eip155:8453"
}

`change`	`changed`	Meaning
`unchanged`	`false`	The page's text is the same as in the baseline. A page already gone in the baseline and still gone is unchanged too.
`changed`	`true`	The page's text differs from the baseline. Fetch it again or check your quote before you rely on it.
`gone`	`true`	The page no longer exists (404 or 410, or the site's name no longer resolves).
`unreadable`	`null`	We could not read the page this time (`page.content_kind` says why), so we cannot say whether it changed. Try again later.

differences lists every compared field that differs, whatever the verdict: content_sha256, raw_sha256, http_status, final_url, content_kind, and with a receipt baseline also server_ip and tls.cert_sha256 when both sides have them.
baseline is what was compared against. With the url form, source is caller and the fields only a receipt carries are null.
elapsed_seconds is the time since the baseline was fetched (null with the url form).
page, text and injection_flags are the new fetch, as [/v1/fetch](/docs/fetch) gives them.

What "changed" means

The comparison is byte for byte on the clean text we extract (content_sha256). Markup-only changes are not changes: raw_sha256 may differ while the answer is unchanged. A page with a date, a counter or rotating text reads as changed on every visit. A content_sha256 from another tool will not match ours: use the hash from our own fetch.

Chaining

The recheck receipt is itself a valid baseline: send it to the next call. Its result.baseline.receipt_sha256 is the SHA-256 of the receipt you sent, so a chain can be checked offline with verify-receipt.mjs.

Charges and errors

The call is charged like /v1/fetch whenever it answers, gone and unreadable included: the fetch was done and the receipt is evidence of it. Every baseline problem is a 400 before payment, never charged:

bad_request: neither or both baseline forms, or content_sha256 without url.
baseline_invalid: the receipt does not verify against this service's keys, is not a fetch, verify/quote or recheck receipt, is a sample, or names no URL; details.reason says which.

The other errors are those of /v1/fetch; see Errors. On the edge, a PDF page answers 501 not_on_edge, uncharged.

Compared with a hosted watch

No schedule, no webhook, nothing stored: you call when you want to know, and pay US$0.003 per check.