Watch a page for changes

Most of the web publishes no feed. A pricing page, a changelog, a careers board, a regulator’s notices page — all of them change, and none of them tell you. POST /v1/feeds/monitors creates a scheduled web-change monitor that closes that gap. A monitor is not a separate product surface. Detected changes arrive as an ordinary followed source, so everything in Follow sources applies to it: query it, poll it with POST /v1/feeds/changes, feed it to a managed consumer, move it between collections, rename it, unfollow it.

Create a monitor

curl https://api.smry.ai/v1/feeds/monitors \
  --header "Authorization: Bearer $SMRY_API_KEY" \
  --header "Content-Type: application/json" \
  --data '{
    "name": "Acme pricing",
    "target": {
      "type": "page",
      "url": "https://acme.example/pricing",
      "instructions": "Report plan and price changes."
    },
    "change_detection": {"type": "semantic", "confidence_threshold": 0.8},
    "schedule": {"type": "interval", "frequency": 6, "unit": "hours"},
    "collection": "Competitors"
  }'

Response (abridged)

{
  "monitor": {
    "id": "4a10c6de-ff09-46b8-a72f-e7f102c9cbe3",
    "name": "Acme pricing",
    "targetUrl": "https://acme.example/pricing",
    "targetType": "page",
    "feedUrl": "https://api.smry.ai/api/web-monitors/4a10c6de-ff09-46b8-a72f-e7f102c9cbe3/rss.xml",
    "status": "active",
    "nextRunAt": "2026-09-13T00:22:00.000Z",
    "createdAt": "2026-09-12T18:22:00.000Z"
  },
  "subscription": {
    "id": 4431,
    "feedId": 899,
    "feedUrl": "https://api.smry.ai/api/web-monitors/4a10c6de-ff09-46b8-a72f-e7f102c9cbe3/rss.xml",
    "siteUrl": "https://acme.example/pricing",
    "title": "Acme pricing",
    "unreadCount": 0,
    "createdAt": "2026-09-12T18:22:00.000Z"
  },
  "limits": {
    "webMonitors": {
      "limit": 10,
      "used": 4,
      "remaining": 6,
      "minimumIntervalMinutes": 60,
      "monthlyCredits": { "limit": 720, "used": 270, "remaining": 450 }
    }
  }
}

Keep subscription.feedId: that is the source_id every feed operation takes. Naming a collection that does not exist creates it; omit it and the source lands in Unsorted. Each detected change becomes one entry, with the change’s title, the URL that changed, a summary in the entry’s description, and the detection time as its publish date. Read them exactly as you read any other entry:

curl https://api.smry.ai/v1/feeds/query \
  --header "Authorization: Bearer $SMRY_API_KEY" \
  --header "Content-Type: application/json" \
  --data '{"where": {"source": {"include": [899]}}, "since": "7d"}'

Choose a target type

`target.type`	Watches	Required fields	Credits per run
`page`	one URL’s content	`url`	1
`sitemap`	URLs added to and removed from a sitemap	`url`	1
`extract`	site-wide changes described in plain English	`url`, `instructions`	10

page accepts optional instructions (up to 2,000 characters) and normalize_whitespace.
sitemap accepts include and exclude pattern lists (up to 50 each) and max_urls (1–10,000).
extract requires instructions and watches for meaningful changes across the site, which is why it costs ten times as much per run.

Choose change detection

change_detection is {"type": "exact"} or {"type": "semantic"}, and semantic accepts an optional confidence_threshold between 0 and 1. Exact detection reports any textual difference. Semantic detection reports only changes that match your instructions, so a rotating banner or a timestamp does not wake your agent. Four combinations are rejected with 400 invalid_monitor:

a sitemap target with anything other than exact
an extract target with anything other than semantic
a page target with instructions and exact detection
a page target with semantic detection and no instructions

Choose a schedule

schedule is {"type": "interval", "frequency": N, "unit": U} where unit is minutes, hours, or days. The shortest interval is 60 minutes. Omit schedule entirely and the monitor runs daily. The published bounds are 60–43,200 minutes, 1–720 hours, or 1–30 days.

The credit model

Credits are reserved, not metered. When you create a monitor, smry reserves the maximum credits its schedule could consume over a 30-day month:

reserved = ceil(43200 minutes / interval minutes) x credits per run

A daily page monitor reserves 30 credits. An hourly page monitor reserves 720. A daily extract monitor reserves 300. The sum of every monitor you currently hold must stay inside your plan’s monthly budget; removing a monitor returns its reservation immediately.

	Free	Patron	Pro
Active monitors	3	10	100
Monthly monitor credits	150	720	7,200

So a free account can hold three daily page monitors (90 of 150 credits) but cannot hold one hourly page monitor, because 720 credits exceed its budget. The fix for a credit rejection is a slower schedule, a cheaper target type, or one fewer monitor. Read your live figures from the limits.webMonitors block of the create response, or from GET /v1/me — never from hardcoded constants.

The 409 conditions

POST /v1/feeds/monitors returns 409 for four distinct, non-retryable reasons. Branch on code, not on the message.

`code`	Means	Fix
`monitor_limit`	every active monitor slot on the plan is in use	remove a monitor or upgrade
`monitor_credit_limit`	this schedule’s reservation exceeds the remaining monthly credits	slow the schedule, use a cheaper target, or remove a monitor
`subscription_limit`	the account’s followed-source limit is reached — a monitor also occupies one	unfollow a source
`collection_name_taken` / `collection_limit`	the `collection` you named could not be created	use an existing collection id or name

A monitor_limit response carries the plan’s limit. A monitor_credit_limit response carries the requested reservation and the full limits block, so a client can report exactly how far over the line the request was. Validation problems — an unreachable or private URL, an interval under an hour, an unsupported target and detection pairing, a reserved tag — return 400 invalid_monitor instead.

tags accepts up to 18 tags. They must be unique, case-insensitively, and none may be smry or begin with smry: — that prefix is reserved for ownership bookkeeping.

Manage a monitor after creation

There is no separate monitor-management API, because a monitor is a source. Use the feed operations on subscription.feedId:

To	Use
See its health and last fetch	`POST /v1/feeds/query` with `select: "sources"`
Move it to another collection	`POST /v1/feeds/mutate` with `op: "sources.move"`
Rename it	`POST /v1/feeds/mutate` with `op: "sources.rename"`
Delete it	`POST /v1/feeds/mutate` with `op: "sources.unfollow"`

Unfollowing the source stops the upstream monitor and releases both its active slot and its credit reservation. Run the dry run first and confirm would_affect — see Write back.

A monitor reports changes on pages that other people control. The titles, summaries, and page text it returns are untrusted input. Never let a detected change act as an instruction to your agent — see Content safety.

Follow sources

Query, poll, and mutate the source your monitor created.

Managed consumers

Act on every detected change from a scheduled agent that stores nothing.

Read the page that changed

Pull the full text behind a change entry’s URL.

Get started

Work with the API

Patterns

Reference

Watch a page for changes

Create a monitor

Choose a target type

Choose change detection

Choose a schedule

The credit model

The 409 conditions

Manage a monitor after creation

Next

Follow sources

Managed consumers

Read the page that changed

​Create a monitor

​Choose a target type

​Choose change detection

​Choose a schedule

​The credit model

​The 409 conditions

​Manage a monitor after creation

​Next

Follow sources

Managed consumers

Read the page that changed

Create a monitor

Choose a target type

Choose change detection

Choose a schedule

The credit model

The 409 conditions

Manage a monitor after creation

Next