Website Change Monitor — text & JSON diff with alerts

Watch any web page or JSON API on a schedule and get a precise answer to "what changed since last time?" — not a screenshot, not a hash, an actual diff:

• HTML pages → main content is extracted (navigation, ads, and footers stripped), then compared paragraph-by-paragraph. You get added and removed paragraphs. Template churn and reordered menus don't trigger false alarms.
• JSON APIs → structural diff: every added / removed / changed path with old and new values ($.prices[3].usd: 42 → 45).
• Webhook alerts — when something changed, the full diff is POSTed to your URL. Wire it to Slack, Zapier, or your own agent.

How to use it

1. Add the URLs you want to watch.
2. Run once — the first run stores a baseline snapshot per URL.
3. Put the actor on an Apify Schedule (e.g. hourly or daily). Every subsequent run reports exactly what changed.

Baselines persist across runs in your own key-value store, isolated per account. Changing the mode or selector starts a fresh watch for that URL (your old baseline is kept under the previous configuration).

Output

One dataset item per URL per run:

{
  "url": "https://example.com/pricing",
  "checked_at": 1755000000,
  "changed": true,
  "mode": "text",
  "added": ["Pro plan is now $29/month"],
  "removed": ["Pro plan is now $19/month"],
  "change_count": 2,
  "prev_checked_at": 1754913600
}

Fetch errors are reported in the item (error field), are never charged, and never overwrite your baseline — a flaky 500 won't make the next run misreport everything as new.

Pricing

Pay per event, nothing else:

• URL checked — each successful check of one URL
• Change detected — only when a check actually found a change

A watch that stays quiet costs you almost nothing; you pay for the news.

Typical uses

• Competitor pricing and changelog pages
• Terms-of-service / policy pages (compliance)
• Job boards, docs pages, status pages
• Any JSON API you depend on but don't control — catch schema or value drift before it breaks you

Support

Issues tab of this actor, or x402@opklaar.com.