Monitors

A monitor captures a baseline of a target, checks the target again on a schedule, and records a change when it finds a difference that counts. Receive changes as signed webhooks, or poll runs and changes through the API.

Pick a target

What you want to know	Target	Detection
Did the visible text on a page change?	`page`	`exact`
Did something I care about change on a page?	`page` with `instructions`	`semantic`
Were URLs added to or removed from a sitemap?	`sitemap`	`exact`
Did something I care about change across a site’s key pages?	`extract`	`semantic`

These are the only supported pairs. Exact detection reports every text difference. Semantic detection confirms a text difference, then asks an AI judge whether it matters under your instructions. When you omit change_detection, it’s inferred from the target as in the table. Extract monitors cost more per run than page and sitemap monitors. See credits.

Create a monitor

This monitor watches a changelog page and reports only the changes its instructions describe. Because the target has instructions, detection is semantic. The examples read your API key from CONTEXT_DEV_API_KEY; the Quickstart shows how to set one up.

import ContextDev from "context.dev";

const client = new ContextDev({ apiKey: process.env.CONTEXT_DEV_API_KEY });

const monitor = await client.monitors.create({
  name: "Changelog announcements",
  target: {
    type: "page",
    url: "https://example.com/changelog",
    instructions: "Report new features, deprecations, and breaking changes. Ignore dates and typo fixes.",
    include_selectors: ["main"],
    exclude_selectors: [".timestamp"],
  },
  webhook: { url: "https://app.example.com/webhooks/context", retry: {} },
});
console.log(monitor.id, monitor.initial_run_id);

import os
from context.dev import ContextDev

client = ContextDev(api_key=os.environ["CONTEXT_DEV_API_KEY"])

monitor = client.monitors.create(
    name="Changelog announcements",
    target={
        "type": "page",
        "url": "https://example.com/changelog",
        "instructions": "Report new features, deprecations, and breaking changes. Ignore dates and typo fixes.",
        "include_selectors": ["main"],
        "exclude_selectors": [".timestamp"],
    },
    webhook={"url": "https://app.example.com/webhooks/context", "retry": {}},
)
print(monitor.id, monitor.initial_run_id)

require "cgi/core"
require "context_dev"

client = ContextDev::Client.new(api_key: ENV.fetch("CONTEXT_DEV_API_KEY"))

monitor = client.monitors.create(
  name: "Changelog announcements",
  target: {
    type: "page",
    url: "https://example.com/changelog",
    instructions: "Report new features, deprecations, and breaking changes. Ignore dates and typo fixes.",
    include_selectors: ["main"],
    exclude_selectors: [".timestamp"],
  },
  webhook: {url: "https://app.example.com/webhooks/context", retry: {}},
)
puts monitor.id, monitor.initial_run_id

package main

import (
	"context"
	"fmt"
	"os"

	contextdev "github.com/context-dot-dev/context-go-sdk/v2"
	"github.com/context-dot-dev/context-go-sdk/v2/option"
	"github.com/context-dot-dev/context-go-sdk/v2/packages/param"
)

func main() {
	client := contextdev.NewClient(option.WithAPIKey(os.Getenv("CONTEXT_DEV_API_KEY")))

	monitor, err := client.Monitors.New(context.Background(), contextdev.MonitorNewParams{
		Name: "Changelog announcements",
		Target: contextdev.MonitorNewParamsTargetUnion{
			OfPage: &contextdev.MonitorNewParamsTargetPage{
				Type:             "page",
				URL:              "https://example.com/changelog",
				Instructions:     contextdev.String("Report new features, deprecations, and breaking changes. Ignore dates and typo fixes."),
				IncludeSelectors: []string{"main"},
				ExcludeSelectors: []string{".timestamp"},
			},
		},
		Webhook: contextdev.MonitorNewParamsWebhook{
			URL:   "https://app.example.com/webhooks/context",
			Retry: param.Override[contextdev.RetryConfigParam](map[string]any{}),
		},
	})
	if err != nil {
		panic(err)
	}
	fmt.Println(monitor.ID, monitor.InitialRunID)
}

<?php
require __DIR__.'/vendor/autoload.php';

use ContextDev\Client;

$client = new Client(apiKey: getenv('CONTEXT_DEV_API_KEY'));

$monitor = $client->monitors->create(
    name: "Changelog announcements",
    target: [
        "type" => "page",
        "url" => "https://example.com/changelog",
        "instructions" => "Report new features, deprecations, and breaking changes. Ignore dates and typo fixes.",
        "includeSelectors" => ["main"],
        "excludeSelectors" => [".timestamp"],
    ],
    webhook: ["url" => "https://app.example.com/webhooks/context", "retry" => []],
);
echo $monitor->id, " ", $monitor->initialRunID, PHP_EOL;

curl https://api.context.dev/v1/monitors \
  -H "Authorization: Bearer $CONTEXT_DEV_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Changelog announcements",
    "target": {
      "type": "page",
      "url": "https://example.com/changelog",
      "instructions": "Report new features, deprecations, and breaking changes. Ignore dates and typo fixes.",
      "include_selectors": ["main"],
      "exclude_selectors": [".timestamp"]
    },
    "webhook": { "url": "https://app.example.com/webhooks/context", "retry": {} }
  }'

The API returns 201 with the monitor and initial_run_id (trimmed):

{
  "id": "mon_123",
  "status": "active",
  "change_detection": { "type": "semantic" },
  "schedule": { "type": "interval", "frequency": 1, "unit": "days" },
  "webhook": {
    "url": "https://app.example.com/webhooks/context",
    "secret": "whsec_…",
    "events": ["change.detected"],
    "retry": { "delays_seconds": [10, 60, 300, 1800, 7200, 21600, 57600] }
  },
  "next_run_at": "2026-09-27T03:14:00.000Z",
  "initial_run_id": "run_123"
}

Creating a monitor queues a baseline run right away. The baseline run captures the first snapshot and never reports a change; later runs compare against it. Pass initial_run_id to Retrieve a monitor run to confirm the baseline worked. If the run couldn’t be queued, initial_run_id is null and the baseline runs at the next scheduled time. Store webhook.secret to verify signatures. With no schedule, the monitor runs once a day; see Schedules.

Access

A restricted API key needs monitors:write to create, update, delete, or run a monitor, rotate its webhook secret, and replay its webhook deliveries. monitors:read covers monitors, runs, changes, limits, credit usage, and delivery history. webhook.secret is returned only to keys with monitors:write. See API keys.

Before you rely on alerts

The baseline run completed: status: "completed" and baseline_created: true.
instructions say what matters and what to ignore.
Your receiver verifies signatures and deduplicates events on X-Context-Id.
Failed runs send no webhook, so you check runs for failures or subscribe to run.completed as a heartbeat.

Targets: page, sitemap, and extract options, detection, and updates.
Schedules: intervals, run now, pause, and automatic pauses.
Runs and changes: run statuses and change records.
Events and alerts: webhook events, delivery failures, and secret rotation.
Limits and errors: monitor limits per plan and error codes.
Website change digests: an end-to-end recipe.
Create a monitor reference

Get started

Web data

Company and people data

Automation

Account and billing

Production

Pick a target

Create a monitor

Access

Before you rely on alerts

​Pick a target

​Create a monitor

​Access

​Before you rely on alerts

​Related

Pick a target

Create a monitor

Access

Before you rely on alerts

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