Immowelt, willhaben & Kleinanzeigen — New Listing Monitor

Most property scrapers hand you the same list every time you run them. This one remembers what it has already seen and returns only listings that appeared since your last run.

Point it at a search, put it on a daily or hourly schedule, and you get the new arrivals — nothing else. In hot markets the good properties are gone within hours, so being first to see them is the whole game.

Supported portals

Portal	Country	Notes
Immowelt	Germany	All German cities, resolved automatically from the city name
willhaben	Austria	Towns and federal states; smaller municipalities matched to their state
Kleinanzeigen	Germany	The place where private, commission-free offers appear

What you get

Every new listing comes back as a normalised record, identical in shape across all three portals:

{
  "id": "immowelt:15872866-cd7d-473d-903d-f8f3a39878b1",
  "portal": "immowelt",
  "url": "https://www.immowelt.de/expose/15872866-cd7d-473d-903d-f8f3a39878b1",
  "title": "Maisonette-Wohnung mit Dachterrasse",
  "price": 289000,
  "currency": "EUR",
  "livingArea": 88.6,
  "rooms": 3,
  "pricePerSqm": 3261.85,
  "postalCode": "04177",
  "city": "Leipzig",
  "district": "Lindenau",
  "floor": "3. Geschoss",
  "energyClass": "C",
  "imageUrl": "https://mms.immowelt.de/example/photo.jpg",
  "images": ["https://mms.immowelt.de/example/photo.jpg"],
  "isPrivate": false,
  "advertiser": { "name": "Beispiel Immobilien GmbH" },
  "isNew": true,
  "detectedAt": "2026-08-10T15:19:04.812Z"
}

Because the shape is the same everywhere, you can watch Germany and Austria side by side and treat the results as one stream. The Output tab shows a photo thumbnail for every listing (imageUrl), not just a wall of numbers.

Getting alerts

Set Webhook for alerts to any HTTPS endpoint and each run with new findings sends a JSON POST containing the new listings. This works with Zapier, Make, n8n, Slack workflows, or your own service — no polling required on your side.

You can also use Apify's built-in integrations to push results into Google Sheets, Slack, or a database.

How to set it up

1. Choose a portal and a location, or paste a Search URL copied straight from the portal. The URL route supports every filter the portal offers, including ones not exposed as fields here.
2. Optionally narrow things down with price, area and room filters.
3. Set a Monitor name if you want to watch several searches in parallel — each name keeps its own history.
4. Run it once to record the baseline, then put it on a schedule.

The first run returns the current stock so you can see what the data looks like; every run after that returns only genuinely new listings. If you are wiring up the webhook straight away and do not want a first alert containing hundreds of existing listings, turn Return everything on the first run off — then the first run stays silent and only records the baseline.

Pricing

You pay a small fee per listing checked, plus a larger fee for each genuinely new listing returned. A run that finds nothing therefore costs very little.

This split exists because the work happens whether or not there is news: to find the three new apartments in Leipzig this morning, the Actor still has to look at the current stock.

Proxies

German and Austrian property portals reject requests coming from data centres with HTTP 403. The Actor therefore uses Apify residential proxies from the matching country by default, and you can supply your own instead. Residential traffic is the main cost driver of every run, which is why the Listings to check per run setting matters — keep it just high enough to cover a day's new arrivals.

Limitations

• Data comes from public search result pages. Fields the portal does not show in the results list (full description, all photos, contact phone numbers) are not included.
• Kleinanzeigen needs a location slug and code from the URL, because it has no name-based lookup.
• Portals change their markup from time to time. If a run reports that no result cards were found, that is the signal — please report it and it will be fixed.

Legal note

The Actor reads publicly accessible listing pages. It does not log in, does not bypass paywalls, and does not collect personal data of private individuals beyond what the portal itself shows publicly. You are responsible for how you use the results, in particular under the GDPR when contacting private sellers.

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Auf Deutsch

Dieser Actor überwacht Immowelt, willhaben und Kleinanzeigen und liefert bei jedem Lauf ausschließlich die Inserate, die seit dem letzten Lauf neu erschienen sind. Er merkt sich zwischen den Läufen, was er schon gesehen hat.

Gedacht ist er für den täglichen oder stündlichen Zeitplan: Sie richten eine Suche ein, hinterlegen optional einen Webhook, und bekommen die Neuzugänge gemeldet, statt jedes Mal dieselbe Liste durchzusehen. In angespannten Märkten entscheidet genau das.

Einrichtung: Portal und Ort wählen — oder einfach die Such-URL aus dem Portal einfügen, dann gelten alle dort gesetzten Filter. Wer mehrere Suchen parallel beobachtet, vergibt je Suche einen eigenen Namen im Feld „Monitor name", damit sich die Verläufe nicht vermischen.

Der erste Lauf gibt den aktuellen Bestand aus, damit Sie sehen, wie die Daten aussehen; ab dem zweiten Lauf kommen nur noch echte Neuzugänge. Wer den Webhook sofort scharf schaltet und keine Benachrichtigung über hunderte Bestandsobjekte will, schaltet „Return everything on the first run" ab — dann bleibt der erste Lauf still und legt nur den Grundbestand an.

Kosten: Sie zahlen einen kleinen Betrag je geprüftem Inserat und einen höheren je tatsächlich neuem Treffer. Ein Lauf ohne Neuzugänge kostet damit fast nichts. Die Aufteilung ist nötig, weil die Arbeit auch dann anfällt, wenn es nichts Neues gibt.

Proxys: Die Portale sperren Anfragen aus Rechenzentren mit HTTP 403. Voreingestellt sind deshalb Apify-Residential-Proxys aus dem passenden Land; eigene Proxys lassen sich hinterlegen.