> ## Documentation Index
> Fetch the complete documentation index at: https://docs.prefetch.io/llms.txt
> Use this file to discover all available pages before exploring further.
# GET /monitor/{id}/checks/{checkId}
> What one check found, page by page: status, diff, and the judge's verdict. Free.
## Overview
Returns one check with a page of its per-page results. Each page carries its status, a diff when it changed, the judge's verdict when the monitor has a goal, and — in json mode — the full current extraction.
Pass `status=changed` to see only the pages that changed. Results are paginated: follow `next` until it is `null`.
## Example request
```bash cURL theme={"theme":"css-variables"}
curl "https://api.prefetch.io/monitor/mon_3f9a1c2b7d4e4f6a8b0c1d2e3f4a5b6c/checks/chk_8e2d4f6a1b3c4d5e6f7a8b9c0d1e2f3a?status=changed" \
-H "X-API-Key: $PREFETCH_API_KEY"
```
```javascript Node.js theme={"theme":"css-variables"}
const url = `https://api.prefetch.io/monitor/${monitorId}/checks/${checkId}?status=changed`;
const res = await fetch(url, { headers: { "X-API-Key": process.env.PREFETCH_API_KEY } });
const { data: check } = await res.json();
for (const page of check.pages) {
if (page.is_meaningful === false) continue; // the judge ruled it noise
console.log(page.url, page.judgment?.reason);
console.log(page.diff?.text ?? JSON.stringify(page.diff?.fields, null, 2));
}
```
```python Python theme={"theme":"css-variables"}
import os, requests
check = requests.get(
f"https://api.prefetch.io/monitor/{monitor_id}/checks/{check_id}",
params={"status": "changed"},
headers={"X-API-Key": os.environ["PREFETCH_API_KEY"]},
).json()["data"]
for page in check["pages"]:
if page["is_meaningful"] is False:
continue
print(page["url"], (page["judgment"] or {}).get("reason"))
```
## Example response
```json theme={"theme":"css-variables"}
{
"success": true,
"data": {
"id": "chk_8e2d4f6a1b3c4d5e6f7a8b9c0d1e2f3a",
"monitor_id": "mon_3f9a1c2b7d4e4f6a8b0c1d2e3f4a5b6c",
"status": "completed",
"trigger": "scheduled",
"scheduled_for": "2026-10-12T06:00:00.000Z",
"started_at": "2026-10-12T06:00:04.112Z",
"finished_at": "2026-10-12T06:01:27.930Z",
"estimated_credits": 55,
"actual_credits": 24,
"summary": { "total_pages": 19, "same": 16, "new": 1, "changed": 1, "removed": 1, "error": 0 },
"target_results": [
{ "target_id": "tgt_8d1e0f2a3b4c5d6e", "type": "scrape", "pages": 1, "checked": 1, "baseline": false },
{ "target_id": "tgt_1a2b3c4d5e6f7a8b", "type": "crawl", "discovered": 17, "limit": 25, "complete": true, "baseline": false }
],
"error": null,
"notifications": { "webhook": { "pending": 0, "delivered": 2, "failed": 0 } },
"pages": [
{
"target_id": "tgt_8d1e0f2a3b4c5d6e",
"url": "https://example.com/pricing",
"status": "changed",
"status_code": 200,
"error": null,
"title": "Pricing — Example",
"previous_check_id": "chk_51b0c2d3e4f5a6b7c8d9e0f1a2b3c4d5",
"is_meaningful": true,
"judgment": {
"meaningful": true,
"confidence": "high",
"reason": "The Starter plan's price went from $19 to $24 a month.",
"meaningful_changes": [
{ "type": "changed", "before": "$19/mo", "after": "$24/mo", "reason": "A plan price changed." }
]
},
"diff": {
"fields": { "plans[0].price": { "previous": "$19/mo", "current": "$24/mo", "change": "changed" } },
"changed_fields": 1
},
"snapshot": {
"json": {
"plans": [
{ "name": "Starter", "price": "$24/mo", "features": ["3 seats", "Email support"] },
{ "name": "Pro", "price": "$49/mo", "features": ["Unlimited seats", "SSO"] }
]
}
}
}
],
"next": null
},
"meta": {
"requestId": "c5a8e9f0-1b2c-4d34-b5e6-708192a3b4c5",
"durationMs": 74
}
}
```
## Check statuses
| Status | Meaning |
| - | - |
| `queued` | Waiting for a worker. |
| `running` | In progress — `pages` already holds what it has recorded. |
| `completed` | Every page was checked. |
| `partial` | Some pages errored, or the check stopped early on credits or its 30-minute limit. Its results are real but incomplete — `error` says why. |
| `failed` | No page could be checked. |
| `skipped_overlap` | The previous check was still running when this one came due. |
| `skipped_no_credits` | The key that owns the monitor had no credits left, or was revoked. Never charged. |
## Reading a page
| Field | Meaning |
| - | - |
| `status` | `same`, `new`, `changed`, `removed` or `error` — see [detecting changes](/api-reference/endpoint/monitor#detecting-changes). |
| `diff.text`, `diff.hunks` | Markdown mode: the unified diff, and the same hunks as structured lines. |
| `diff.fields` | Json mode: each changed field by JSON path, with `previous`, `current` and `change` (`added`, `removed` or `changed`). |
| `diff.truncated` | The diff was larger than the stored cap. `added_lines` and `removed_lines` still count all of it. |
| `is_meaningful`, `judgment` | The judge's verdict and its reasoning. `null` when the page was not judged. |
| `snapshot.json` | Json mode: the full current extraction, so you never need to re-fetch the page. |
| `previous_check_id` | The check whose snapshot this one was compared with. |
A page that is new since the first check carries its whole content as an all-added diff. Removed pages carry no diff.
## Related
Find a check id.
Get the same page objects pushed to you.
## OpenAPI
````yaml GET /monitor/{id}/checks/{checkId}
openapi: 3.1.0
info:
title: Prefetch API
description: >-
Extract brand identity, company data, screenshots, IAB classifications, and
clean page content from any URL.
version: 1.0.0
contact:
email: support@prefetch.io
servers:
- url: https://api.prefetch.io
description: Production
security:
- apiKey: []
tags:
- name: Endpoints
description: Data extraction endpoints. All require authentication and consume credits.
- name: Health
description: Health and readiness probes. No authentication required.
paths:
/monitor/{id}/checks/{checkId}:
get:
tags:
- Endpoints
summary: Get a check
description: >-
One check with a page of its per-page results: status, diff, the judge's
verdict and, in JSON mode, the current extraction. Filter with
`status=changed` to see only what changed, and follow `next` until it is
null. Free.
operationId: getMonitorCheck
parameters:
- $ref: '#/components/parameters/monitorId'
- $ref: '#/components/parameters/monitorCheckId'
- $ref: '#/components/parameters/monitorPageSkip'
- $ref: '#/components/parameters/monitorPageLimit'
- $ref: '#/components/parameters/monitorPageStatus'
responses:
'200':
description: Check with page results.
content:
application/json:
schema:
type: object
properties:
success:
type: boolean
enum:
- true
data:
$ref: '#/components/schemas/MonitorCheckDetailData'
meta:
$ref: '#/components/schemas/Meta'
required:
- success
- data
- meta
example:
success: true
data:
id: chk_8e2d4f6a1b3c4d5e6f7a8b9c0d1e2f3a
monitor_id: mon_3f9a1c2b7d4e4f6a8b0c1d2e3f4a5b6c
status: completed
trigger: scheduled
scheduled_for: '2026-10-12T06:00:00.000Z'
started_at: '2026-10-12T06:00:04.112Z'
finished_at: '2026-10-12T06:01:27.930Z'
estimated_credits: 55
actual_credits: 24
summary:
total_pages: 19
same: 16
new: 1
changed: 1
removed: 1
error: 0
target_results:
- target_id: tgt_8d1e0f2a3b4c5d6e
type: scrape
pages: 1
checked: 1
baseline: false
- target_id: tgt_1a2b3c4d5e6f7a8b
type: crawl
discovered: 17
limit: 25
complete: true
baseline: false
error: null
created_at: '2026-10-12T06:00:00.513Z'
updated_at: '2026-10-12T06:01:27.930Z'
notifications:
webhook:
pending: 0
delivered: 2
failed: 0
pages:
- target_id: tgt_8d1e0f2a3b4c5d6e
url: https://example.com/pricing
status: changed
status_code: 200
error: null
title: Pricing — Example
previous_check_id: chk_51b0c2d3e4f5a6b7c8d9e0f1a2b3c4d5
is_meaningful: true
judgment:
meaningful: true
confidence: high
reason: The Starter plan's price went from $19 to $24 a month.
meaningful_changes:
- type: changed
before: $19/mo
after: $24/mo
reason: A plan price changed.
diff:
fields:
plans[0].price:
previous: $19/mo
current: $24/mo
change: changed
changed_fields: 1
snapshot:
json:
plans:
- name: Starter
price: $24/mo
features:
- 3 seats
- Email support
- name: Pro
price: $49/mo
features:
- Unlimited seats
- SSO
- target_id: tgt_1a2b3c4d5e6f7a8b
url: https://example.com/changelog/2026-10-11
status: new
status_code: 200
error: null
title: October 11 release
previous_check_id: null
is_meaningful: false
judgment:
meaningful: false
confidence: high
reason: A bug-fix release; no plan or price changes.
meaningful_changes: []
diff:
text: |
--- previous
+++ current
@@ -1,0 +1,4 @@
+# October 11 release
+
+- Fixed CSV export of invoices
+- Faster dashboard loading
added_lines: 4
removed_lines: 0
truncated: false
hunks:
- old_start: 1
old_lines: 0
new_start: 1
new_lines: 4
lines:
- type: added
content: '# October 11 release'
- type: added
content: ''
- type: added
content: '- Fixed CSV export of invoices'
- type: added
content: '- Faster dashboard loading'
snapshot: null
next: >-
/monitor/mon_3f9a1c2b7d4e4f6a8b0c1d2e3f4a5b6c/checks/chk_8e2d4f6a1b3c4d5e6f7a8b9c0d1e2f3a?skip=2&limit=2
meta:
requestId: c5a8e9f0-1b2c-4d34-b5e6-708192a3b4c5
durationMs: 74
'400':
description: Invalid or missing parameters. The message names the field.
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
'401':
description: Missing API key.
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
'403':
description: >-
Revoked key, expired key, credit limit, blocklisted URL, monitor
limit reached, or a RapidAPI subscription — monitors need a direct
Prefetch API key.
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
'404':
description: Monitor or check not found.
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
'429':
description: Rate limit exceeded.
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
'503':
description: Monitoring is temporarily unavailable. Retry shortly.
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
components:
parameters:
monitorId:
name: id
in: path
required: true
description: The monitor id returned by `POST /monitor`.
schema:
type: string
example: mon_3f9a1c2b7d4e4f6a8b0c1d2e3f4a5b6c
monitorCheckId:
name: checkId
in: path
required: true
description: A check id, from `GET /monitor/{id}/checks` or `POST /monitor/{id}/run`.
schema:
type: string
example: chk_8e2d4f6a1b3c4d5e6f7a8b9c0d1e2f3a
monitorPageSkip:
name: skip
in: query
required: false
description: >-
Page results to skip. Use the `next` link rather than building this by
hand.
schema:
type: integer
minimum: 0
default: 0
monitorPageLimit:
name: limit
in: query
required: false
description: Page results to return per request.
schema:
type: integer
minimum: 1
maximum: 100
default: 25
monitorPageStatus:
name: status
in: query
required: false
description: Only pages with this status — `changed` to see just what changed.
schema:
type: string
enum:
- same
- new
- changed
- removed
- error
schemas:
MonitorCheckDetailData:
allOf:
- $ref: '#/components/schemas/MonitorCheckData'
- type: object
properties:
notifications:
type: object
properties:
webhook:
type: object
nullable: true
description: >-
Webhook deliveries for this check, by outcome. `null` when
the monitor has no webhook.
properties:
pending:
type: integer
delivered:
type: integer
failed:
type: integer
pages:
type: array
items:
$ref: '#/components/schemas/MonitorCheckPage'
next:
type: string
nullable: true
description: URL for the next page of results, or null.
Meta:
type: object
properties:
requestId:
type: string
format: uuid
description: Unique identifier for this request.
example: a3f2c1d4-7b6e-4f2a-9c1d-8e3f2a1b4c5d
durationMs:
type: integer
nullable: true
description: Time taken to process the request in milliseconds.
example: 1842
required:
- requestId
- durationMs
ErrorResponse:
type: object
properties:
success:
type: boolean
enum:
- false
description: >-
Always false. Absent, like `meta`, on authentication and rate-limit
errors, which are answered before a request is processed.
error:
type: string
description: >-
Human-readable error message. The wording can change: branch on
`error_code`.
example: Credit limit exceeded
error_code:
type: string
enum:
- INVALID_REQUEST
- PAYLOAD_TOO_LARGE
- NOT_FOUND
- CONFLICT
- UNAUTHORIZED
- FORBIDDEN
- CREDITS_EXHAUSTED
- RATE_LIMITED
- CONCURRENCY_LIMITED
- URL_BLOCKED
- URL_NOT_PERMITTED
- DNS_RESOLUTION_FAILED
- TARGET_BLOCKED
- TARGET_CONNECTION_FAILED
- TARGET_TIMEOUT
- TARGET_SSL_ERROR
- TARGET_SERVER_ERROR
- TARGET_CLIENT_ERROR
- TARGET_NOT_A_PAGE
- TARGET_UNLOADABLE
- RESEARCH_INCONCLUSIVE
- TIMEOUT
- SERVICE_BUSY
- SERVICE_UNAVAILABLE
- INTERNAL_ERROR
description: >-
What went wrong, for machines. Stable: a code keeps its meaning once
published. See [Error handling](/concepts/errors).
example: CREDITS_EXHAUSTED
retryable:
type: boolean
description: >-
Whether the same request can succeed if sent again after a short
wait (honour `Retry-After` when present). False for problems with
the request or the target.
example: false
retryAfterSeconds:
type: integer
description: 'On `RATE_LIMITED`: seconds until a request will be accepted.'
limit:
type: integer
description: >-
On `CONCURRENCY_LIMITED`: how many requests this key may have in
flight.
meta:
$ref: '#/components/schemas/Meta'
required:
- error
- error_code
- retryable
MonitorCheckData:
type: object
properties:
id:
type: string
example: chk_8e2d4f6a1b3c4d5e6f7a8b9c0d1e2f3a
monitor_id:
type: string
status:
type: string
enum:
- queued
- running
- completed
- failed
- partial
- skipped_overlap
- skipped_no_credits
description: >-
`partial`: some pages errored, or the check stopped early on credits
or its time limit — its results are real but incomplete.
`skipped_overlap`: the previous check was still running.
`skipped_no_credits`: the owning key had no credits or was revoked.
Skipped checks are never charged.
trigger:
type: string
enum:
- scheduled
- manual
scheduled_for:
type: string
format: date-time
nullable: true
started_at:
type: string
format: date-time
nullable: true
finished_at:
type: string
format: date-time
nullable: true
estimated_credits:
type: integer
nullable: true
description: Upper bound, computed when the check was queued.
actual_credits:
type: integer
description: >-
What the check was charged: pages fetched at the `/scrape` rate,
plus pages judged.
summary:
$ref: '#/components/schemas/MonitorSummary'
target_results:
type: array
nullable: true
items:
type: object
description: >-
Per target: pages checked, and for crawls whether the crawl ran to
completion. Only a complete crawl can report removed pages.
error:
type: string
nullable: true
description: >-
Why the check is partial, failed or skipped, or what it could not
do.
created_at:
type: string
format: date-time
updated_at:
type: string
format: date-time
MonitorCheckPage:
type: object
properties:
target_id:
type: string
url:
type: string
status:
type: string
enum:
- same
- new
- changed
- removed
- error
status_code:
type: integer
nullable: true
error:
type: string
nullable: true
title:
type: string
nullable: true
previous_check_id:
type: string
nullable: true
description: The check the compared snapshot was taken in.
is_meaningful:
type: boolean
nullable: true
description: The judge's verdict, or `null` when the page was not judged.
judgment:
allOf:
- $ref: '#/components/schemas/MonitorJudgment'
nullable: true
diff:
allOf:
- $ref: '#/components/schemas/MonitorDiff'
nullable: true
description: For changed pages, and for pages that are new since the first check.
snapshot:
type: object
nullable: true
properties:
json:
type: object
nullable: true
description: 'JSON mode: the full current extraction.'
MonitorSummary:
type: object
properties:
total_pages:
type: integer
same:
type: integer
new:
type: integer
changed:
type: integer
removed:
type: integer
error:
type: integer
MonitorJudgment:
type: object
properties:
meaningful:
type: boolean
confidence:
type: string
enum:
- high
- medium
- low
reason:
type: string
example: The Starter plan's price went from $19 to $24 a month.
meaningful_changes:
type: array
items:
type: object
properties:
type:
type: string
enum:
- added
- removed
- changed
before:
type: string
nullable: true
after:
type: string
nullable: true
reason:
type: string
nullable: true
MonitorDiff:
type: object
properties:
text:
type: string
nullable: true
description: 'Markdown mode: a unified diff of the page''s markdown.'
example: |
--- previous
+++ current
@@ -3,3 +3,3 @@
-Starter — $19/mo
+Starter — $24/mo
hunks:
type: array
items:
$ref: '#/components/schemas/MonitorDiffHunk'
description: 'Markdown mode: the same diff as structured hunks.'
added_lines:
type: integer
removed_lines:
type: integer
truncated:
type: boolean
description: >-
The diff was larger than the stored cap. The line counts still cover
all of it.
too_large:
type: boolean
description: The page changed almost entirely, so no line diff was computed.
fields:
type: object
description: >-
JSON mode: changed fields keyed by JSON path, each `{ previous,
current, change }`.
example:
plans[0].price:
previous: $19/mo
current: $24/mo
change: changed
changed_fields:
type: integer
fields_truncated:
type: boolean
MonitorDiffHunk:
type: object
properties:
old_start:
type: integer
old_lines:
type: integer
new_start:
type: integer
new_lines:
type: integer
lines:
type: array
items:
type: object
properties:
type:
type: string
enum:
- added
- removed
- context
content:
type: string
securitySchemes:
apiKey:
type: apiKey
in: header
name: X-API-Key
description: Your Prefetch API key. Obtain one from the dashboard.
````
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