Who this is for: anyone deciding which price tracker to rely on for a specific international trip, and anyone whose current alerts are not doing what they expected.
How we know: Sources are listed at the end. Every claim about a competitor comes from that company's own help center, blog, terms page or app-store listing, loaded on the date shown above. Claims about Wildly describe what the product does today; they are not statistics.
When people search for flight price alerts compared, they usually want one answer: which tool will tell me first when my flight gets cheap? The honest answer is that the five tools below do five different jobs. Google Flights tracks a route or an exact itinerary and emails you on "significant" changes. Kayak sends a daily digest or a real-time alert on roughly a 10 percent move. Hopper is a phone app built around predictions and push notifications. Skyscanner ties alerts to saved searches. Wildly checks the route you name once a day and emails you when the fare crosses a target you set. Which one is best depends on whether you want a prediction, a digest, or a threshold.
The comparison table
| | Google Flights | Kayak | Hopper | Skyscanner | Wildly | |---|---|---|---|---|---| | What you track | A route on specific dates, "any dates" for a route, or one exact itinerary | A route on your dates; also flexible-destination and "Top 25 Cities" alerts | A trip you searched in the app | A route and date you saved | A route, dates and cabin, with a target price and up to plus or minus 3 days of flexibility | | Trigger | Price changes "significantly" | Daily digest, or real-time on "typically a 10% increase or drop" | App decides when it is "the best time to buy" | "when the flight price changes" | Fare at or below your target, checked daily | | Channel | Email | Email and push (daily digest); the blog also mentions text | Push notification in the app | Email (per third-party descriptions; not verified, see note) | Email; SMS on the paid plan | | Frequency | Not published; "any dates" gets a monthly email | Once a day, early morning, or real-time | Not published | Not verified | Once a day | | Prediction | Yes ("prices are likely to increase", "unlikely to drop") | Yes (Price Forecast, next seven days) | Yes (the core feature) | Not verified | No | | Price history shown | Price graph over two months | Not published | Not published | Not published | Daily observations on route pages; bands once history accumulates | | Refund if price drops | Price guarantee on badged itineraries, US only, $5 minimum, $500 a year cap | No | Price Freeze (a paid hold, not a refund) | No | No | | Login required | Google account | Kayak account | App account | Skyscanner account (per third-party descriptions) | Email address | | Cost | Free | Free | Free app, paid add-ons | Free | Free plan; paid plan adds SMS and more routes |
Each cell is expanded below with the source it comes from.
Google Flights
Google's help page says you turn on Track prices after choosing airports, dates, stops, cabin and passenger count. You can track specific dates or "any dates". For specific dates, Google says you receive emails when prices for a tracked flight or route change significantly. For "any dates", Google sends a monthly email when the route's minimum price drops notably, or a regular update with the best available prices if there is no large drop. Google also says it may email you when "prices for a route you track are likely to go up", including an estimate and a confidence level (Google Travel Help).
Tracked routes live on a Tracked Flights page where you can toggle notifications or remove a route. Google does not publish how often it re-checks a tracked route, and "significantly" is not defined in the help text. That is the main weakness for a traveler with a specific number in mind: you cannot tell Google "email me at $700".
The separate price insights feature explains what Google means by low and high: "Prices are less than usual" is shown when a fare is significantly below what Google expects "based on an analysis of past prices of similar trips", and "Prices are unlikely to drop before you book" is shown when Google predicts with high confidence that the fare will not fall before departure (Google Travel Help).
Google's price guarantee is not an alert feature, but it matters for the same decision. Under the guarantee terms, only itineraries with the "Google Price Guarantee" badge qualify, the price difference must be $5 or more, payouts cap at $500 per account per calendar year, and money is paid through Google Pay after the first flight is flown (Google Price Guarantee terms). Our companion guide on how Google Flights price tracking works covers the alert failure modes in detail.
Kayak
Kayak is the most explicit of the five about cadence. Its help center says: "Most Price Alerts are sent once a day. We bundle all your active alerts into one email or push notification, usually sent in the early morning." You can instead choose real-time alerts, which "trigger when there's a significant price change, typically a 10% increase or drop, since your last update" (KAYAK Help). Alerts expire once the travel date passes, and Kayak says they can also expire if you stop opening the emails.
Kayak's blog adds three alert types: exact-date tracking, a "Flexible Flight Price Alert" for a destination without fixed dates, and "Top 25 Cities" alerts for a region (KAYAK blog). The blog also describes Price Forecast, which "uses historical data to predict the right time to book flights". The help center is candid that "predictions based on past history can never be perfect".
Kayak's weakness for a specific trip is the same as Google's: the trigger is a percentage move or a daily summary, not a price you chose. A 10 percent swing on a $1,400 transpacific fare is $140, which is a big move; on a $300 Caribbean fare it is $30, which is noise. Consumer Reports' 2016 shopping test noted Kayak's alerts as a useful tool for fares bought well in advance, "weekly or even daily notices when the price falls" (Consumer Reports).
Hopper
Hopper's own description is that you "watch a trip right in the app and we'll send you a notification when it's the best time to buy, recommending you to book now, or maybe wait just a little longer" (Hopper on the App Store). Its 2021 welcome article says "Watch a Trip" lets Hopper "monitor prices 24/7 and notify you the instant there's a deal", claims that Hopper "predicts future flight and hotel prices with 95% accuracy", and confirms the service is app-only (Hopper).
Hopper is the right choice if you want to be told what to do and are comfortable with push notifications on a phone. It is the wrong choice if you want email, a desktop workflow, or a plain record of what the fare has been. Hopper's help center articles on predictions and notifications did not return readable content when we loaded them, so the accuracy claim above is quoted from Hopper's marketing, not independently checked.
Skyscanner
Skyscanner's help center returned an access error every time we tried to load it while writing this guide, so we are limiting the Skyscanner row to what Skyscanner says in its own App Store listing: "Set up a Price Alert and we'll let you know when the flight price changes so you're always booking at the right time", plus a "saved" feature for flights you heart and an "Everywhere" search (Skyscanner on the App Store). Third-party guides describe email alerts tied to a login and a cadence that depends on how far out the trip is; we could not verify that from Skyscanner directly, so treat those details as unconfirmed.
Wildly
Wildly does one narrower thing. You open /alerts/new, pick an origin and destination, the travel dates and cabin, set a target price, and optionally widen the dates by up to plus or minus 3 days. Wildly then checks that exact search on Google Flights once a day and emails you when the lowest fare is at or below your target. Text alerts and a larger number of watched routes are on the paid plan; the free plan has no card and no expiry (details on /pricing).
Where Wildly is weaker than the others, plainly:
- No predictions. Wildly does not tell you whether to wait. Google, Kayak and Hopper all do.
- Once a day, not real time. If a fare appears and vanishes within hours, a daily check can miss it. Kayak's real-time option and Hopper's push notifications are faster.
- Email only on the free plan. No app, no push.
- Young data. Wildly records daily prices on about 240 routes; route pages show observed ranges as they accumulate. On a route with a short history, the typical/good/great bands are wide and the page says so. How the observations are made is on /methodology.
Where Wildly is stronger: the trigger is your number, not a percentage; the check is the same search every day, so the series on a route page such as Seattle to Tokyo or New York to London is comparable day to day; and you can see the observation date next to every fare.
How to choose
- You have exact dates and a number in your head: set a Wildly alert with a target, and also turn on Google tracking for the same dates so you get Google's "likely to go up" warnings.
- You are flexible on destination: Kayak's flexible and Top 25 Cities alerts, or Google's "any dates" tracking, are built for that.
- You want to be told when to buy: Hopper, with the caveat that the accuracy figure is Hopper's own.
- You want a refund if the price falls after you book: only Google offers that, only on badged itineraries, and only up to the caps above.
A reasonable setup for a big trip is two tools: one that predicts (Google or Hopper) and one that fires on a threshold you chose (Wildly or Kayak real-time). They fail in different ways. For a worked method on deciding whether a fare is good, see Is this a good flight price?. To see what a route's observed prices look like before you set a number, open a route page such as Chicago to Cancun or a destination hub such as flights to Tokyo.
FAQ
Which flight price alert is most accurate? None of the five publishes an audited accuracy figure for alerts. Hopper publishes a 95 percent prediction accuracy claim in its own materials. Google and Kayak describe their forecasts as based on past prices and say they can be wrong. Wildly makes no predictions, so "accuracy" for Wildly means whether the daily observation matched Google Flights on the day, which you can check yourself because the check date is printed on the page.
Can I set a specific target price in Google Flights? No. Google's help page describes emails on significant changes and on likely increases, not a user-set threshold. Kayak's real-time alert fires on a roughly 10 percent change. Wildly alerts fire on a price you set.
Do price alerts cost money? Google Flights, Kayak and Skyscanner alerts are free with an account. Hopper is a free app with paid add-ons such as Price Freeze. Wildly has a free plan; the paid plan adds SMS and more watched routes.
Should I use more than one alert service? Yes, if the trip matters. A predictive tool and a threshold tool cover each other's blind spots, and running Google tracking alongside a Wildly alert costs nothing.
Sources
- Google Travel Help: Track flights & prices: https://support.google.com/travel/answer/6235879
- Google Travel Help: How to find the best fares with Google Flights: https://support.google.com/travel/answer/7664728
- Google Price Guarantee Additional Terms of Service: https://travel.google.com/intl/ALL_us/flights/guarantee/terms/
- KAYAK Help: Pricing and Price Alerts: https://www.kayak.com/c/help/pricing/
- KAYAK Travel Hacker Blog: Track flight prices & save with Price Alerts: https://www.kayak.com/news/flight-price-alerts/
- Hopper: Welcome to Hopper: https://media.hopper.com/articles/welcome-to-hopper
- Hopper on the App Store: https://apps.apple.com/us/app/hopper-flights-hotels-cars/id904052407
- Skyscanner on the App Store: https://apps.apple.com/us/app/skyscanner-flights-hotels/id415458524
- Consumer Reports: How to Get the Lowest Airfares: https://www.consumerreports.org/airline-travel/how-to-get-the-lowest-airfares