Last updated 21 October 2026. This policy covers the Chrome extension named Kerbio and the website kerbio.co.uk.
When you open a property listing on rightmove.co.uk, zoopla.co.uk or onthemarket.com, the extension reads the listing's location (postcode and map coordinates) from the page you are viewing and shows Article 4 status, HMO licensing rules, licensed HMOs nearby, and a sold-price comparison for that council. On the search results pages of those same three sites, it adds a small status badge to each result card (Article 4, licensed HMOs nearby, price vs sold comparison, and whether you've already saved that listing) using the same page data, read locally in your browser. It does nothing on any other website.
The extension never sends Kerbio your name, email address, account details or browsing history. To answer questions about the listing you are viewing, it makes the requests below. Requests to Kerbio and to the public data services carry no identifier for you.
api.postcodes.io (to identify the council and area; on a results page, the coordinates of up to 100 listings at once) and to www.planning.data.gov.uk, the UK Government planning data service (Article 4 directions, conservation areas and listed buildings at that point).deluxe-cascaron-2fd7ae.netlify.app, the same service as kerbio.co.uk, hosted by Netlify):
data/flags.json) that can switch the shared price history off; it contains no code and nothing about you is sent to fetch it. When the site publishes an area rent table (ONS private rents by council), it is downloaded the same way.extensionpay.com), which processes payments through Stripe. If you start a trial or subscribe, ExtensionPay holds your email address and payment status, and shares your email address and trial or subscription status with us so we can help with billing questions. The extension only asks ExtensionPay whether your installation is paid or in trial. We never see your card details.All stored locally in your browser (chrome.storage.local), never sent to us:
The extension can prepare a print-ready letter addressed to "The Owner" at a property address: the listing you are viewing, or licensed HMOs near it drawn from the council registers already bundled with the extension or downloaded from our own site (see below). The letters contain no names and no data from the register beyond the property address; the recipient is always "The Owner". Nothing is fetched or sent to produce them, and the extension does not post or send anything on your behalf: you print and send the letters yourself and you are responsible for them, including honouring any request not to be contacted again (the built-in suppression list is there for that).
No analytics, no tracking cookies, no advertising, and no sale of data. We do not receive your name, email address (other than from ExtensionPay, above) or browsing history, and nothing you save to your pipeline, your notes, your letters or your saved searches leaves your browser. The only listing information we receive is what is described above: postcodes for energy certificate lookups, the areas of the data files you download, and anonymous listing numbers and prices for the shared price history.
storage: to cache your payment status locally, and small preferences such as whether you have dismissed the prompt asking for a review.rightmove.co.uk, zoopla.co.uk and onthemarket.com: to read the page you are viewing and draw the panel, or the small status badges on results pages. No data is sent to these sites. The extension holds no other access to the portals or to SpareRoom. On a results page the extension reads only the page you are viewing: the filter chips and badges use each card's own summary and the portal's own dates. It does not open the listings' pages, read further pages of your search, or re-check saved searches. The extension makes no requests to any listing portal or rental site other than reading the page you are viewing. The prices on the listing or results page in front of you are remembered on your device so that a later price drop can be pointed out. They are also sent to our site as anonymous price observations (the portal's listing number, the price, the date it was seen and the date the portal says it was listed; nothing about you, no account, no identifier) and merged with every other user's observations into a shared price history that all users see. Only prices on pages you are actually viewing are shared. You can turn this sharing off in the extension's popup at any time. Saved searches are stored on your device and open again from the extension's popup; they are not re-checked. Version 1.1.4 and earlier re-ran saved Rightmove searches once a day and shared the prices those checks and the "Search all results" scan found, in the same anonymous form as above.api.postcodes.io, www.planning.data.gov.uk and extensionpay.com: the services described above.deluxe-cascaron-2fd7ae.netlify.app: our own server, for the reference data, energy certificate lookups and shared price history described above.Article 4 results come from data councils publish to the national planning data service, which is incomplete. Where a council has published nothing, the extension says so rather than showing "no". Sold-price comparisons come from HM Land Registry Price Paid Data, a public dataset with no bedroom counts, so they compare by street, distance and house type, not size. Always confirm with the council before making an offer.
kerbio.co.uk uses no tracking cookies and no analytics scripts. Links from our pages to the spreadsheet pages carry the kind of page you came from (for example "lha-reading" for the Reading LHA page). If you then buy, that label is passed to Stripe, our payment processor, with your order, so we can see which pages lead to sales. It says nothing about you.
If you ask to receive the monthly HMO Article 4 changes bulletin, a reminder about your landlord database registration (with the region you choose), or an alert when a council's HMO rules change (with the council you choose), we keep your email address only to send you that bulletin, reminder or alert. We don't share it, sell it or use it for anything else. Reply "unsubscribe" (or use the link in any bulletin) and we delete it.
Other websites can embed our HMO Article 4 postcode checker. It sets no cookies. When a visitor checks a postcode, their browser sends it to postcodes.io and planning.data.gov.uk to work out the answer, exactly as on our own site, and Kerbio does not store it. We count how the embedded checker is used (how often it loads and how often its buttons are used), keyed only by an optional label the website adds and the website's address; we store those totals and nothing else: no IP addresses, cookies or identifiers. If a visitor chooses to sign up for an alert in the checker, we receive their email address and the council they asked about, use it only to tell them about changes to that council's HMO rules, and delete it when they unsubscribe. The website hosting the checker has its own privacy policy.
Luke Rallings, enquiries@swiftresolve.co.uk