Page content monitoring (Content monitor)

Content monitor watches the content, not the resource availability: Notifly fetches the specified URL every N seconds, extracts the value of interest from the response and compares it with the previous one. As soon as the value changes — an alert is sent. This is an active monitor (Notifly initiates the check), but it answers the question “what changed on the page” rather than “is the site up”.

Typical use cases:

• Price — track the price of a product on a store page or a competitor’s site.
• Status / availability — “in stock” ↔ “out of stock”, order status, service status.
• Competitor content — a new blog post appeared, the price list changed, the changelog updated.
• JSON API — the value of a field in a public JSON response (rate, balance, version).

Extraction modes

What to compare is defined by the mode (mode). Five modes are supported:

mode	What is extracted	Field selector
hash	SHA-256 of the entire response body — alert on any page change	not needed
json	Value by JSONPath from a JSON response	required — JSONPath, e.g. $.price or $.items.0.status
text	Substring by regular expression from the response text	regex; if empty — behaves like hash
css	Text of the first element matched by a CSS selector	required — valid CSS selector
xpath	Text of the first node matched by an XPath expression	required — valid XPath expression

The check logic is the same for all modes: extract the value → compare with the stored lastValue → if different, send an alert and remember the new value. The first check just stores the current value and does not send an alert.

JSONPath in json mode

Simple traversal like $.a.b and array indexing $.a.0.b are supported ($ and the leading dot are optional). For a JSON response, specify json instead of text — the value will be taken from the parsed structure rather than the raw text.

Multiple rules in one monitor

Instead of a single mode+selector you can provide an array of rules (rules) — up to 20 rules per monitor. Each rule is { "mode", "selector", "label" }, where label is an optional human-readable name. An alert is triggered if any rule changed. This is convenient when you need to monitor several values on the same page (e.g., price + availability + rating).

"rules": [
  { "mode": "css",  "selector": ".product-price",      "label": "Цена" },
  { "mode": "css",  "selector": ".availability",        "label": "Наличие" },
  { "mode": "text", "selector": "Скидка\\s+\\d+%",      "label": "Скидка" }
]

If rules is set, top-level fields mode/selector are ignored. If rules is empty — the single mode (mode+selector) works, preserved for backward compatibility.

JavaScript pages: useBrowser

By default the page is loaded via a plain HTTP GET. If the needed value is injected by scripts in the browser (SPA, lazy-loaded price, etc.), enable the flag useBrowser: true — then the page is rendered via headless Chromium and values are extracted from the final DOM after JS execution.

Browser mode — only if configured on the server

Chromium rendering is available only when the corresponding container is running on the server. If it is not configured, the test and selector probing will gracefully fall back to a plain GET and this will be indicated in the note field of the response (“Test used a plain HTTP GET; JavaScript-rendered content may differ from the live monitor”). In that case values visible only after JS may differ from the live monitor.

Selector testing and selection

Before creating a monitor, it is convenient to try and validate a rule on the fly — there are two endpoints that do not require creating a monitor.

Test a rule — POST /content-monitor/test-rule

Loads the page and applies a single rule, returning the extracted value or a clear error:

curl -X POST "$NOTIFLY_URL/content-monitor/test-rule" \
     -H "Content-Type: application/json" \
     -H "X-Notifly-Key: <client-token>" \
     -d '{
       "url": "https://example.com/product/42",
       "useBrowser": false,
       "mode": "css",
       "selector": ".product-price"
     }'
# → {"ok":true,"value":"1 299 ₽"}

Response: ok (boolean), value (extracted value, truncated to 200 characters), error (error text, if the rule failed) and note (diagnostics, e.g. about browser mode fallback to GET).

Suggest a selector using AI — POST /content-monitor/suggest-selector

Notifly loads the page once, compresses the HTML and in one request to the LLM chooses the mode and selector according to your description. The result is always verified on the real page content, so the response contains a valid sampleValue:

curl -X POST "$NOTIFLY_URL/content-monitor/suggest-selector" \
     -H "Content-Type: application/json" \
     -H "X-Notifly-Key: <client-token>" \
     -d '{
       "url": "https://example.com/product/42",
       "useBrowser": false,
       "prompt": "следить за ценой товара"
     }'

The response includes: mode, selector, label, sampleValue (current value on the page), reason (why), confidence (high/medium/low), alternatives (other candidates) and fallback (true if the LLM is unavailable and the selector was chosen heuristically). The prompt field is up to 500 characters. A request like “monitor the whole page” will immediately return hash mode without calling the LLM.

AI selector billing

One call to suggest-selector consumes one AI request from the daily quota — only if prompt is provided and the LLM is configured on the server. Without a prompt (or with the LLM disabled) a heuristic is used and it is not billed. See Quotas and tariffs.

Creating a monitor

Via the dashboard

1. Open app.notifly.ru → Monitors → Content.
2. Enter the URL, choose a mode (or click “Suggest selector” and describe in words what to monitor), enable useBrowser if needed.
3. Use the “Test” button to ensure the extracted value is exactly what you need.
4. Set the interval, alert text and priority — and save.

Via the REST API — POST /content-monitor

Single mode (monitoring one CSS value):

curl -X POST "$NOTIFLY_URL/content-monitor" \
     -H "Content-Type: application/json" \
     -H "X-Notifly-Key: <client-token>" \
     -d '{
       "appid": 12345,
       "name": "Цена товара #42",
       "url": "https://example.com/product/42",
       "mode": "css",
       "selector": ".product-price",
       "useBrowser": false,
       "intervalSec": 3600,
       "timeoutSec": 15,
       "alertMessage": "Цена товара #42 изменилась!",
       "alertPriority": 7
     }'

Multiple mode (several rules on one page):

curl -X POST "$NOTIFLY_URL/content-monitor" \
     -H "Content-Type: application/json" \
     -H "X-Notifly-Key: <client-token>" \
     -d '{
       "appid": 12345,
       "name": "Карточка товара",
       "url": "https://example.com/product/42",
       "rules": [
         { "mode": "css",  "selector": ".product-price", "label": "Цена" },
         { "mode": "css",  "selector": ".availability",   "label": "Наличие" }
       ],
       "intervalSec": 3600,
       "alertMessage": "Изменилось содержимое карточки товара.",
       "alertPriority": 5
     }'

Monitoring a field in a JSON API:

curl -X POST "$NOTIFLY_URL/content-monitor" \
     -H "Content-Type: application/json" \
     -H "X-Notifly-Key: <client-token>" \
     -d '{
       "appid": 12345,
       "name": "Курс из API",
       "url": "https://api.example.com/rates",
       "mode": "json",
       "selector": "$.usd.value",
       "intervalSec": 600,
       "alertMessage": "Курс USD изменился."
     }'

Request fields

Field	Type	Required	Description / constraints
appid	uint	yes	ID of the application (channel) to send the alert to
name	string	yes	Monitor name, 1–200 characters
url	string	yes	Valid http(s) URL
mode	string	yes*	Single mode: hash / json / text / css / xpath
selector	string	depends	JSONPath for json, regex for text, CSS for css, XPath for xpath; required for json/css/xpath
rules	array	yes*	Array of rules {mode, selector, label}, up to 20; alternative to mode+selector
useBrowser	bool	no	true — render via headless Chromium
intervalSec	uint	yes	Check interval, 60–86400 seconds
timeoutSec	uint	no	Load timeout, default 15, maximum 60
alertMessage	string	yes	Alert text, 1–2000 characters
alertTitle	string	no	Alert title
alertMessageMarkdown	bool	no	Treat alert text as Markdown
alertPriority	int	no	Alert priority, 0–10

* You must set either rules (multiple mode) or mode+selector (single mode). If rules is non-empty — mode/selector are ignored.

Lifecycle and statuses

A new monitor is created with status pending and is checked almost immediately (nextCheckAt = “now”). After changing “significant” fields (URL, mode, selector, rules, useBrowser, interval, timeout) the check is rescheduled for “now”. Cosmetic edits (name, alert title/message, priority) do not shift the schedule.

• POST /content-monitor/:id/pause — pause (checks are not performed; nextCheckAt is moved far into the future).
• POST /content-monitor/:id/resume — resume (status becomes pending again, check is scheduled for “now”).

The monitor record stores lastValue (last extracted value), lastError (last load/extraction error), lastCheckAt, nextCheckAt and alertedAt.

Limits

• Check interval: 60–86400 seconds (1 minute to 24 hours).
• Load timeout: default 15 s, maximum 60 s.
• Up to 20 rules per monitor.
• Alert priority: 0–10; name length — 1–200, alertMessage — 1–2000 characters.
• Requests originate from the cloud, so the target URL must be accessible from the public internet.
• Browser mode (useBrowser) works only if the corresponding container is configured on the server.

REST API

All endpoints require a client token (or an MCP code with write rights for mutating operations); the list is available in read-only mode too. More about tokens in First login.

Method	Path	Description
GET	/content-monitor	List of the user’s content monitors
POST	/content-monitor	Create a monitor
POST	/content-monitor/suggest-selector	Suggest mode + selector with AI by description
POST	/content-monitor/test-rule	Apply one rule to a page (dry-run), return value or error
PUT	/content-monitor/:id	Update settings (cannot change appid)
DELETE	/content-monitor/:id	Delete a monitor
POST	/content-monitor/:id/pause	Pause checks
POST	/content-monitor/:id/resume	Resume checks

See also: Active monitors, HTTP monitors, Workflow monitors, Browser-workflow.