Pricing

from $5.00 / 1,000 url checkeds

Semantic Change Detector

Monitor web pages for meaningful content changes, ignoring noisy timestamps and counters. Optional webhook alerts on change. $0.005/URL + $0.02 start.

Pricing

from $5.00 / 1,000 url checkeds

Rating

0.0

(0)

Developer

Andok

Actor stats

Bookmarked

Total users

Monthly active users

4 days ago

Last modified

Features

Two sensitivity modes — meaningful (ignores timestamps/counters) or any (raw text diff)
CSS selector scoping — check only the part of the page you care about (e.g. a pricing table or article body)
Persistent snapshots — stores the last-seen state per URL in a named key-value store (semantic-change-snapshots), so subsequent runs detect real drift over time
Diff excerpts — see exactly which lines were added/removed on change
Webhook alerts — optional fire-and-forget JSON POST when a change is detected
Resilient per-URL errors — a failed fetch on one URL never stops the batch

Input

Field	Type	Required	Default	Description
`urls`	`array`	Yes	—	Web pages to check
`selector`	`string`	No	—	CSS selector to scope extraction (defaults to `<body>`)
`sensitivity`	`"any"` \| `"meaningful"`	No	`"meaningful"`	Change detection strictness
`webhookUrl`	`string`	No	—	URL to POST a JSON payload to when a change is detected

Input Example

{
  "urls": ["https://example.com/pricing"],
  "selector": ".pricing-table",
  "sensitivity": "meaningful",
  "webhookUrl": "https://your-app.com/webhooks/change-alert"
}

Output

{
  "url": "https://example.com/pricing",
  "changed": true,
  "change_summary": "Content changed: 2 line(s) added, 1 line(s) removed.",
  "diff_excerpt": "- Starter plan: $9/mo\n+ Starter plan: $12/mo\n+ New Enterprise tier available",
  "checked_at": "2026-07-23T16:00:00.000Z"
}

Field	Description
`url`	The input URL, as provided
`changed`	`true` if the content differs from the last stored snapshot
`change_summary`	Human-readable summary of the change (or lack thereof)
`diff_excerpt`	Up to 8 removed + 8 added lines (`-`/`+` prefixed), truncated to ~2000 characters. `null` if unchanged
`checked_at`	ISO timestamp of this check
`error`	Present only if the fetch/extraction failed for this URL

On the first check for a URL there is no baseline yet, so changed is false and the snapshot is simply stored for future comparisons.

How "meaningful" filtering works

Before hashing/diffing, each extracted line has the following heuristics applied to strip volatile noise:

ISO 8601 timestamps, numeric dates, month-name dates
Clock times (10:30, 10:30:00 AM)
Relative timestamps (5 minutes ago, yesterday, just now)
Engagement counters (1,234 views, 12 comments, 3.4k likes)

These are regex-based heuristics, not a guarantee: some volatile content may occasionally slip through, and rarely meaningful text containing dates/numbers may be stripped along with them. Use sensitivity: "any" if you want a literal raw-text diff instead.

Pricing

Event	Cost
Actor start	$0.02
URL Checked	$0.005

Typical run cost: 100 URLs ≈ $0.02 + 100 × $0.005 = $0.52.

Limitations

Static HTML only — this Actor fetches raw HTML via fetch + Cheerio; it does not execute JavaScript. Pages that render their content client-side (SPAs) may show no extractable text. Use a URL that serves server-rendered HTML, or point at an API/RSS endpoint instead.
Snapshots are capped at 4,000 lines per URL to keep key-value store items small; extremely long pages may be truncated.
Webhook delivery is fire-and-forget with a 10s timeout and no retries — failures are logged but never fail the run.
The named key-value store (semantic-change-snapshots) persists across runs of the same Actor on the same account, so re-running with the same URLs will correctly detect drift since the last run.

Use Cases

Track competitor pricing pages for changes
Monitor legal/ToS pages for updates
Watch documentation pages for silent edits
Alert on job posting or status page changes

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