DiffHook

DiffHook's core bet is that web-change monitoring should be infrastructure, not a reader. Everything on the site reinforces that: the docs start with an API key and a bearer token, monitors are described as URL + interval + destination objects, and the delivery promise is an HTTP POST containing a diff plus metadata. If you've been nursing a cron job and a scraped-hash script, the pitch is straightforward — replace it with something that signs its payloads, retries with exponential backoff, and keeps a delivery log you can hand to an auditor. The product surface is wider than the webhook framing suggests. You can monitor a full web page, a single CSS/XPath selector, a JSON API, a sitemap, or an RSS/Atom feed from the same account, and switch check types per monitor. Two distinct check types matter for budgeting: lightweight checks (15,000/mo on Starter, 150,000 on Pro, 750,000 on Business) and visual checks for pixel-level UI changes (2,000 / 10,000 / 50,000). Both are metered. AI alert modes — price, availability, new items, or a custom prompt — shipped January 2026 and are gated to Pro and Business, which is the sharpest functional line in the ladder: on Starter you get the same polling engine but no AI noise filtering. On delivery, the operational details are the differentiator. HMAC webhook signatures let your endpoint verify authenticity; automatic retries with exponential backoff cover the common case of an endpoint briefly down; the delivery log covers 30 days on Starter, 90 on Pro, and a year on Business (50 GB / 150 GB / 500 GB of storage, extendable at $5 per 100 GB). Log entries are pruned once the storage limit is hit, so retention is a real constraint for compliance work. Where it fits: engineering, DevOps, revenue ops, compliance, and sales teams who already have a queue, CRM, ticketing system, or workflow tool to receive the event. Where it doesn't: marketing or analyst teams who want to open a dashboard and read a change summary with no automation downstream — the value is on the other side of the webhook. The published Free tier (5 monitors, daily checks) is honestly a taster, not a production plan; the 15,000-check ceiling on Starter is the other number to watch if your watch list is wide or your polling interval is aggressive. Pricing is flat and published, with no per-check metering, which makes cost forecasting unusually easy for this category.