Why the price sometimes differs when you click through
You find a flight for €89, click "book", and the airline says €104. Nobody lied to you - you just crossed from one kind of price to another. Knowing the difference makes you a sharper shopper on every flight site, not just this one.
Two kinds of prices power every flight site
Live quotes come from asking the airline's inventory, right now, for your exact itinerary. They're accurate for minutes and expensive to produce - which is why booking sites make you wait a few seconds and sometimes "re-price" at checkout.
Cached fares are prices that were recently observed - by other travellers' searches, or periodic sweeps - and stored. They're instant to display and cheap to serve at scale, which is why exploration tools (price calendars, "everywhere" maps, deal alerts, and WRVR's whole-month searches) are built on them. The trade-off is age: a cached fare is a photograph of a moving object.
Every major flight-search product mixes the two: caches for browsing breadth, a live check at the end. The difference between products is mostly where they draw that line and how honestly they label it.
Why the number moves
Fare buckets sell out. Airlines sell each flight in price tiers with limited seats. If the last €89 seat sold an hour after the fare was cached, the live price is the next tier up.
Fares also go down. Airlines adjust to demand in both directions; re-checks land lower more often than people expect, especially outside peak season.
Currency and fees. A fare cached in one currency, displayed in another, and booked in a third can shift a few percent on exchange rates - and checkout adds payment/baggage/seat fees the base fare never included.
Different sellers. The same seat is often sold by the airline and several agencies at slightly different prices; the cache may have seen one seller, your click-through another.
How WRVR handles it
WRVR is an exploration tool, and it's explicit about the pipeline:
Every price is marked indicative, with a freshness note - "seen today", "seen 3d ago" - taken from when the fare was last observed. Fresher is more reliable.
Round-trip and open-jaw totals are the sum of two independently-priced one-way fares. That's what lets the engine compare thousands of date pairings instantly - and it's also why you confirm each leg live before booking, from the "check live price" links on every result.
Each leg also links the same route and dates on Google Flights, Skyscanner, and Kiwi - engines with their own data pipelines - so a cross-check is one click, not a re-typed search.
Shopping well with indicative prices
Use cached prices to choose, live prices to buy. The cache's job is comparison: which destination, which weekend, which route shape. It's very good at that - relative order is much more stable than absolute numbers.
Check freshness before excitement. A price seen today is close to bookable; a price seen a week ago on a fast-selling route is a rumor. Treat stale outliers (a fare wildly below everything comparable) with suspicion - bucket that cheap usually sells out first.
Verify both legs of an open-jaw. Two separate tickets means two separate confirmations. Do them in one sitting so the trip you compared is the trip you book.
If the live price jumped, re-shop, don't chase. The whole point of searching a window is that the second-cheapest date is usually within a few euros. Go back, take the next option, and you've lost almost nothing.
The honest summary
No tool can show you guaranteed prices for a thousand date combinations at once - the airlines don't sell data that way. What a good exploration tool can do is be fast, broad, and truthful about freshness, then hand you to a live check before money moves. That's the contract here, stated plainly.