Monitors

A monitor checks pages on a schedule and compares each one with the previous check. Instead of polling a pricing page, a changelog or a policy page yourself, you get a webhook or an email with just the change.

Create

POST /monitor with what to watch, how often, and optionally a goal that describes which changes matter.

Baseline

The first check records every page. Nothing is announced, because every page is new.

Check

Each scheduled check fetches every page again and marks it same, new, changed, removed or error, with a diff.

Get told

Changes that match your goal are posted to your webhook and emailed to your addresses. You can also read any check with GET /monitor/{id}/checks/{checkId}.

Example request

This monitor watches a competitor’s pricing page for price changes and their changelog for new posts, every weekday morning:

curl -X POST "https://api.prefetch.io/monitor" \
  -H "X-API-Key: $PREFETCH_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Competitor pricing",
    "schedule": { "text": "every weekday at 9am", "timezone": "Europe/Athens" },
    "goal": "Alert me when a plan price or its included features change",
    "targets": [
      {
        "type": "scrape",
        "urls": ["https://example.com/pricing"],
        "change_tracking": { "modes": ["json"], "json_prompt": "Each plan: name, monthly price, headline features" }
      },
      {
        "type": "crawl",
        "url": "https://example.com/changelog",
        "crawl_options": { "limit": 25, "include_paths": ["^/changelog/"] }
      }
    ],
    "webhook": { "url": "https://you.example.org/hooks/prefetch" },
    "email": { "to": ["[email protected]"] }
  }'

const res = await fetch("https://api.prefetch.io/monitor", {
  method: "POST",
  headers: { "X-API-Key": process.env.PREFETCH_API_KEY, "Content-Type": "application/json" },
  body: JSON.stringify({
    name: "Competitor pricing",
    schedule: { text: "every weekday at 9am", timezone: "Europe/Athens" },
    goal: "Alert me when a plan price or its included features change",
    targets: [
      {
        type: "scrape",
        urls: ["https://example.com/pricing"],
        change_tracking: { modes: ["json"], json_prompt: "Each plan: name, monthly price, headline features" },
      },
      {
        type: "crawl",
        url: "https://example.com/changelog",
        crawl_options: { limit: 25, include_paths: ["^/changelog/"] },
      },
    ],
    webhook: { url: "https://you.example.org/hooks/prefetch" },
    email: { to: ["[email protected]"] },
  }),
});

const { data } = await res.json();
console.log(data.id, data.schedule.cron, data.webhook.secret);

import os, requests

r = requests.post(
    "https://api.prefetch.io/monitor",
    headers={"X-API-Key": os.environ["PREFETCH_API_KEY"]},
    json={
        "name": "Competitor pricing",
        "schedule": {"text": "every weekday at 9am", "timezone": "Europe/Athens"},
        "goal": "Alert me when a plan price or its included features change",
        "targets": [
            {
                "type": "scrape",
                "urls": ["https://example.com/pricing"],
                "change_tracking": {"modes": ["json"], "json_prompt": "Each plan: name, monthly price, headline features"},
            },
            {
                "type": "crawl",
                "url": "https://example.com/changelog",
                "crawl_options": {"limit": 25, "include_paths": ["^/changelog/"]},
            },
        ],
        "webhook": {"url": "https://you.example.org/hooks/prefetch"},
        "email": {"to": ["[email protected]"]},
    },
)
monitor = r.json()["data"]
print(monitor["id"], monitor["webhook"]["secret"])

Example response

{
  "success": true,
  "data": {
    "id": "mon_3f9a1c2b7d4e4f6a8b0c1d2e3f4a5b6c",
    "name": "Competitor pricing",
    "status": "active",
    "schedule": { "cron": "0 9 * * 1-5", "timezone": "Europe/Athens", "text": "every weekday at 9am" },
    "next_run_at": "2026-10-12T06:00:00.000Z",
    "last_run_at": null,
    "current_check_id": null,
    "goal": "Alert me when a plan price or its included features change",
    "judge_enabled": true,
    "targets": [
      { "id": "tgt_8d1e0f2a3b4c5d6e", "type": "scrape", "urls": ["https://example.com/pricing"], "...": "every option, with its effective value" },
      { "id": "tgt_1a2b3c4d5e6f7a8b", "type": "crawl", "url": "https://example.com/changelog", "...": "..." }
    ],
    "webhook": {
      "url": "https://you.example.org/hooks/prefetch",
      "headers": {},
      "metadata": {},
      "events": ["monitor.page", "monitor.check.completed"],
      "secret": "whsec_4f1c9e2a7b3d8e6f0a5c1b9d2e7f3a8c4b6d0e1f9a2c5b7d"
    },
    "email": {
      "to": ["[email protected]"],
      "recipients": [
        { "address": "[email protected]", "status": "active", "confirmation_sent_at": null, "confirmed_at": "2026-10-09T10:00:00.000Z", "unsubscribed_at": null }
      ]
    },
    "retention_days": 30,
    "estimated_credits_per_check": 55,
    "estimated_credits_per_month": 1155,
    "last_check_summary": null,
    "created_at": "2026-10-09T10:00:00.000Z",
    "updated_at": "2026-10-09T10:00:00.000Z"
  },
  "meta": {
    "requestId": "b8f1d2e3-4a5b-4c6d-8e7f-9a0b1c2d3e4f",
    "durationMs": 61
  }
}

The status is 201 Created. Keep the webhook.secret: you need it to verify each webhook. You can read it again with GET /monitor/{id}. To take the baseline straight away instead of waiting for the schedule, call POST /monitor/{id}/run.

The parts of a monitor

Targets

Fixed pages, a whole site section, or a web search.

Schedules

Plain phrases or cron, in any timezone.

Detecting changes

Text diffs, tracked JSON fields, and how to cut noise.

Goals and judging

One sentence that decides which changes you hear about.

Alerts

Webhooks and email.

Limits and credits

What a check costs, and what each plan allows.

Credits

Creating, reading and changing a monitor is free. Each check costs 1 credit per page fetched, plus extra for json extraction, search targets and judging. See Limits and credits.

A monitor bills on every check for as long as it’s active. A crawl target with limit: 100 on a 5-minute schedule fetches 28,800 pages a day. Start small, and pause monitors you aren’t using.

Monitors need a direct Prefetch API key. They aren’t available through RapidAPI, which bills from a response header, and a scheduled check runs when there’s no response to carry one.

Get started

Agents and MCP

Company data

Web data

Jobs and monitoring

Platform

Going to production

Example request

Example response

The parts of a monitor

Targets

Schedules

Detecting changes

Goals and judging

Alerts

Limits and credits

Credits

​Example request

​Example response

​The parts of a monitor

Targets

Schedules

Detecting changes

Goals and judging

Alerts

Limits and credits

​Credits

Example request

Example response

The parts of a monitor

Credits