Key takeaways
- Underbook is a hotel price tool with a Chrome extension, a web price checker based on Google Hotels listings, a daily email watch and a Watch my booking feature for refundable reservations.
- It tracks a hotel's typical nightly rate for your dates, not one specific room, so you check the room and total yourself before rebooking.
- Underbook's page does not describe searching the same hotel from other countries (checked on November 8, 2026).
- Arbitrica, a personal AI agent, searches the same hotel from 195 countries, checks the room and final total, and prepares the booking at the lowest price in the world.
Short answer
If you like Underbook but want the price from other countries too, the alternative is Arbitrica. Underbook shows what booking sites list for your hotel and emails you when the going rate drops. Arbitrica is a personal AI agent that searches the same hotel from 195 countries at the checkout, checks that the room and final total match, and prepares the booking at the lowest price in the world for you to review and pay. Research across 1,000 hotels searched from 100 countries found a lower price than the traveller's own in about 80% of countries, with a typical gap of 20-40%.
What Underbook does
According to Underbook's own guide (October 2026, checked on November 8, 2026):
- Chrome extension: lines up the room you are viewing across other booking sites, side by side.
- Web price checker: shows what each booking site lists on Google Hotels for your hotel and dates; works on a phone.
- Email watch: rechecks the hotel's going rate once a day and emails you if it drops at least 5% on two daily checks in a row.
- Watch my booking: tracks a refundable reservation against what you paid until free cancellation ends, and emails once if the rate is at least 5% and $5 a night lower on two daily checks.
Underbook says it may earn a commission if you book through its link, and that this never changes the prices shown.
Where Underbook stops
- One country. Its page describes comparing booking sites and Google Hotels listings, not the same hotel searched from other countries.
- Typical rate, not your room. It tracks the typical nightly rate for a hotel and dates, so you check the room and all-in total before you rebook.
- You do the booking. It alerts you; you rebook and cancel yourself.
The country gap is often the biggest one. In Arbitrica's own price check, the same Istanbul hotel and 4 nights were $1,066 from the UK and $708 from India, and 4 of 10 hotels were lower from another country by up to 33.6%.
Underbook and Arbitrica at a glance
| Underbook | Arbitrica | |
|---|---|---|
| What it is | Price checker, extension and email alerts | Personal AI agent at the checkout |
| Other countries searched | Not described | 195 |
| What it checks | Typical nightly rate across booking sites | The same hotel and room, with the final total including taxes and fees |
| Booking | You book yourself | Prepared for you; you review and pay |
| After you book | Watch my booking emails once on a 5% drop | Keeps searching until free cancellation ends |
Related: something like PriceMice for every booking site, Hotel Ninja alternative and is Pruvo still working?
Frequently asked questions
What is a good Underbook alternative?
Arbitrica, if you also want the price from other countries: it searches the same hotel from 195 countries, checks the room and final total, and prepares the booking at the lowest price in the world. Hotel Ninja and RatePunk line up booking sites from your own country, as Underbook does.
What does Underbook do?
It offers a Chrome extension that lines up booking sites' prices, a web checker based on Google Hotels listings, a daily email watch and a Watch my booking feature for refundable reservations.
Does Underbook check prices from other countries?
Its page does not describe searching the same hotel from other countries (checked on November 8, 2026).
Does Underbook track my exact room?
No. Underbook says it tracks the typical nightly rate for a hotel and dates, so you check the room and total before rebooking.
Does Arbitrica book the hotel for me?
Arbitrica automatically prepares everything for the booking at the lowest price it finds, in a new tab. You only review the details and complete the payment.
Does Arbitrica keep checking the price after I book?
Yes. Its approach repeats the search after you book until the free-cancellation window ends, and a new booking is confirmed before the original one is cancelled.