Underbook: Hotel Price Comparison & Tracker by Underbook

Underbook double-checks the hotel you are already looking at.

On a hotel page at Booking.com, Expedia or Hotels.com (and on many other booking sites and hotels' own websites), Underbook looks up the same stay across booking sites and tells you, right on the page, whether another site lists it for less. Prices are compared all-in where the sites report taxes and fees. If a hotel page is not picked up automatically, click the Underbook toolbar button to run the check.

HONEST BY DESIGN
A lower price is only useful if it is for the same room. When Underbook can match the room name, it says so. When it cannot, it says that too and shows you the room and terms side by side, so you decide. When the site you are on already has the lowest price we found, we tell you that instead of inventing a saving.

WHY BOTHER
In our September 2026 study of 424 hotels in 25 cities, 78% had at least one site listing the stay 5% or more below the going rate. A second snapshot of 434 hotels three days later found 79%, and a third of 427 hotels in 25 new cities found 81%. Most of those cheaper listings did not name a matching room, which is exactly why Underbook shows you the room before you switch. Full data: https://underbook.co/hotel-price-dispersion-study

HOW IT WORKS
1. Shop for hotels as you always do.
2. On a hotel page, Underbook checks other booking sites for the same dates and party size.
3. If one is cheaper, you see the price, the site, the room and whether free cancellation is labelled. You always book on the site you choose.

PRICE-DROP ALERTS (optional)
Click "Email me if the price drops" and enter your email. Underbook checks the typical rate for those dates once a day and emails you when it drops at least 5% on two daily checks in a row. One click stops it. No account needed.

WHAT UNDERBOOK SENDS, AND WHY
- To compare prices, the extension sends the hotel name, your dates, the number of adults and the site's market and currency to Underbook's price service. It does not send your identity, the pages you visit or any payment details.
- Anonymous usage statistics (for example, "a comparison was shown") are sent only if you allow technical and interaction data. They never include hotel names, dates, URLs or your email.
- Your email is stored only if you set a price watch, and only to send that alert.
- We never see your card and we do not sell data.
Full policy: https://underbook.co/privacy

HOW UNDERBOOK IS FREE
When you open a booking site through Underbook and book, we may earn a commission from that site at no extra cost to you. It never changes which prices we show or their order.

No extension handy? Check any hotel on the web: https://underbook.co/hotel-price-checker
Questions: hi@underbook.co