Do airline shopping portals share the same platform?

Some do, and some don't, but the boundary isn't obvious from outside. Open the American AAdvantage eShopping portal, then United MileagePlus Shopping, then Delta SkyMiles Shopping and click around: that déjà vu is real, because those three, plus Southwest Rapid Rewards Shopping and Alaska's Atmos Rewards Shopping, run on one shared platform with each airline's branding stretched over the same storefront.

Same store catalog. Same tracking. Same click-through-then-shop mechanics. What's different is each airline's own promotions, and which currency lands in your account when you're done (miles for most of these five, points for Southwest and Alaska - a naming choice each program makes for itself, not a technical difference between platforms).

Here's where it usually gets told wrong, though. You'll read that every airline portal runs on this one platform, a dozen carriers all in one place. They don't. Of the 11 airline portals we track, a second group runs on a completely separate shared platform: JetBlue TrueBlue Shopping, plus the international programs Flying Blue, Emirates Skywards, Asia Miles and Virgin Atlantic Shops Away. One more, the Aeroplan eStore, sits on a platform of its own.

So the accurate version is a handful of platforms, each wearing several airlines' colors, not one platform wearing all of them. Useful shortcut, you just need to know which group your airline is actually in.

Why this matters more than it sounds

When two portals run on the same platform, the plumbing really is shared, and two things follow that save you real time:

• The store list barely differs between airlines on the same platform. Of the roughly 1,370 stores that show up on any of American, United, Delta, Southwest or Alaska's portals, about seven in eight show up on all five, because all five are reading from the same catalog. Cross into the other platform and that overlap gets messier: a store on the American/United/Delta group may or may not be sitting on JetBlue's.
• Earn rates move in loose lockstep across one platform, but never perfectly. The platform is shared; the promotions each airline funds are not. So one airline will occasionally out-earn the rest on a given store, usually during a promo the others aren't running.

Here's one store, Samsung, across every airline portal that currently carries it:

Six of the eleven airline portals we track show a Samsung rate right now: three pay in miles (AA, Delta, United), three pay in points (Alaska, Southwest, Aeroplan). Look at how those numbers line up, or don't. When two portals on the same platform quote the same rate, the mechanics behind them are identical, so the tiebreaker is simply which currency you'd actually use. When they don't line up, that's usually a promotion one airline is funding, and the platform has nothing to do with it, exactly the gap a side-by-side comparison exists to catch.

So which airline portal should you use?

When two portals share a platform, their store list and tracking are basically the same, so pick on the currency, not the portal:

• Value the miles or points you'll actually redeem. United miles, AA miles, Delta SkyMiles, Rapid Rewards points, Atmos points: none of them are worth the same to everyone, and none convert to each other. Choose whichever one you have a real plan to spend.
• Watch for a spend bonus or a boosted rate. A spend bonus is a one-time reward for crossing a spending threshold ("spend $150, get 500 bonus miles"); a boosted rate is the ordinary per-dollar rate temporarily raised above its usual level (both are defined in the portal glossary if either is new to you). These get funded by the airline, not the platform, so they run on each airline's own calendar, not unlike the seasonal bumps we've tracked on the cashback side. In late July and early August, all five of these portals ran a "Back-to-School Bonus" spend campaign within days of each other: same three-tier shape, different dollar thresholds each airline set for itself. That's what a shared platform actually buys an airline: the promotions machinery, not the promotion itself. Catch the next one on our rate changes feed.
• Don't stop at the five portals that share this platform. American, United, Delta, Southwest and Alaska are one group. The JetBlue and international programs are a second, and the Aeroplan eStore is a third on its own, each carrying its own store list and its own rates. They get overlooked precisely because everyone assumes all airline portals are interchangeable.
• Mind the first-purchase bonus. New to an airline's portal? Several pay new members a one-time bonus on a first qualifying purchase. United's own terms, for instance, promise 250 bonus miles once a new member's purchases hit $100 within 7 days of getting the offer. One-time, but free, and worth checking before you assume the ongoing rate is the whole story.

If you'd rather not comb through all eleven one at a time, here's what's paying its highest mileage rate right now, across the airline portals that pay in miles:

The points-paying portals (Southwest, Alaska, JetBlue, Virgin Atlantic, Aeroplan) don't show up in that particular list, only their currency differs, not their standing; check them the same way on the full, always-live Rate highs page.

What to actually do with this

The airline portals want you to think of all eleven as separate destinations. Underneath, most of them are one of three sets of plumbing wearing eleven sets of logos, and knowing which portal sits on which platform tells you where to expect the same store list and where you actually have to go check. Use that: shop the store you were buying from anyway, compare the currencies across the airline portals that carry it on its store page, and route through whichever one you'll actually burn, meaning spend it on an award rather than hoard it. If cash beats miles for what you're buying today, we've ranked the cashback side of this the same way.

Want the long version, with the mechanics of how airline portals pay and how to read mi/$? That's the airline shopping portals guide.