Know the Moment a Website Changes Its Tech Stack

Automated monitoring scans websites on a schedule and alerts you via webhooks when technologies are added, removed, or upgraded. API-first. Starting at $9/mo.

Start Monitoring See the API Docs

How It Works

Create a Webhook

POST /webhooks
{
  "domain": "competitor.com",
  "callback_url": "https://your.app/hook"
}

Enable Monitoring

Set a monitoring interval. DetectZeStack will scan the domain daily or weekly, automatically.

PATCH /webhooks/{id}
{
  "monitor_interval": "daily"
}

Receive Change Events

When the tech stack changes, you get an HMAC-signed webhook payload with exactly what changed.

POST your.app/hook
X-Signature: sha256=abc...
{
  "event": "tech_stack.changed",
  "changes": [...]
}

Example Webhook Payload

When a monitored domain's tech stack changes, you receive an HMAC-signed tech_stack.changed event at your callback URL.

{
  "event": "tech_stack.changed",
  "domain": "competitor.com",
  "changes": [
    {
      "type": "added",
      "technology": {
        "name": "Next.js",
        "version": "14.1",
        "categories": ["JavaScript frameworks"],
        "confidence": 100
      }
    },
    {
      "type": "removed",
      "technology": {
        "name": "Create React App",
        "categories": ["JavaScript frameworks"],
        "confidence": 100
      }
    },
    {
      "type": "version_changed",
      "technology": {
        "name": "React",
        "version": "18.2",
        "categories": ["JavaScript libraries"],
        "confidence": 100
      },
      "previous_version": "17.0",
      "new_version": "18.2"
    }
  ],
  "technologies": [ "..." ],
  "meta": { "status_code": 200, "tech_count": 18, "scan_depth": "full" },
  "timestamp": "2026-03-31T08:15:00Z"
}

Query the Change Feed API

Don't want webhooks? Query /changes to pull a feed of all technology changes across your monitored domains.

GET /changes?domain=stripe.com&days=30

{
  "changes": [
    {
      "domain": "stripe.com",
      "technology": "React",
      "change_type": "added",
      "category": "JavaScript frameworks",
      "created_at": "2026-03-30T14:22:00Z"
    }
  ],
  "count": 1,
  "history_days": 90,
  "tier": "pro"
}

Use Cases

Competitive Intelligence

Know when competitors switch frameworks, adopt new analytics, or upgrade infrastructure. Trigger sales outreach: "We noticed you just migrated to Next.js…"

Security Monitoring

Detect when a vendor adds unknown libraries or downgrades a secure component. Feed changes into your vulnerability management pipeline via the CPE field.

Migration Tracking

Monitoring a client's Angular-to-React migration? Get notified at each stage without manual scanning. Track progress across weeks or months.

Sales Signals

Prospects who just adopted Stripe, HubSpot, or Salesforce are actively buying. Trigger outbound when their tech stack shifts. Learn more.

DetectZeStack vs BuiltWith Alerts

Feature	DetectZeStack	BuiltWith
Starting price	$9/mo	$295/mo
Alert delivery	Webhook + API	Email only
HMAC signing	SHA-256	No
Change history API	Yes (/changes)	No API access
Monitoring intervals	Daily, Weekly	Unknown
API-first	Yes	No
Free tier	100 requests/mo	No

Monitoring Plans

Monitoring is included in every paid tier. Monitoring scans do not count against your monthly API request quota.

Tier	Price	Webhooks	Intervals	Change History
Free	$0	5	—	7 days
Basic	$9/mo	20	Daily, Weekly	30 days
Pro	$29/mo	50	Daily, Weekly	90 days
Business	$79/mo	100	Daily, Weekly	365 days

Frequently Asked Questions

How does monitoring differ from the /analyze endpoint?

The /analyze endpoint is on-demand: you send a request, you get a result. Monitoring runs on a schedule (daily or weekly) and pushes a webhook to your callback URL only when something changes. You don't need to poll.

What counts as a "change"?

Three types: added (a new technology appeared), removed (a technology disappeared), and version_changed (the detected version number changed). Each change includes the full technology object with name, version, categories, and confidence.

Do monitoring scans count against my request quota?

No. Monitoring scans are system-initiated and do not count against your monthly API request limit. Your quota is only consumed by on-demand /analyze, /batch, /compare, and /changes calls.

Can I monitor without webhooks — just query /changes?

Yes. Every /analyze call records a snapshot. The /changes endpoint shows diffs between consecutive snapshots for any domain. No webhook required. Webhooks add real-time push delivery on top of the pull-based /changes feed.

Start Monitoring in 2 Minutes

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