Why I built CheckBeforeYouShop (and how the tracking works)

Straight up - I'm one person, and I built this because I was annoyed.

For years, my version of checking meant tab-cycling through multiple portals before a big purchase, picking the highest rate, and moving on. I knew I was leaving some cashback on the table, but there's only so many tabs and portals I could manage before getting overwhelmed - was 6% at this store good, or did it pay 9% last month and I just missed it? Was I leaving miles on the table by skipping the airline portals? The tools I was using showed me today's rate. None of them told me whether today's rate was any good.

So I started tracking the rates myself. That grew into this.

What it actually does

CheckBeforeYouShop reads the portals' own pages and records what they pay over time: cashback sites, airline mileage portals, points portals. (New to portals? Here's the whole thing in 30 seconds.) Today it's tracking:

• 49,135 stores
• across 44 portals

The "over time" part is the key differentiator. Since CBYS has each store's rate history, across 40+ portals, we can actually answer the question: is this rate good, for this store, today? Each store gets a verdict, measured against its own past rates.

How the tracking works (no magic)

The site checks portals every 6 to 24 hours. It reads each portal's rate pages, and saves what's showing. Every change we spot lands on the rate changes feed, like these:

Over time, we collect more history; this history is how we compute the "good rate?" verdict.

A few principles I hold myself to:

• Native units, always. CBYS shows all portals in their native currency, be it cash, miles, or points. In your account, you can set cent per point (CPP) valuations for points and miles to make it easier to scan portals and see which one is the best for you to use, given how you value each currency.
• Freshness shows on the number. Every rate shows when CBYS last confirmed it. If a check hasn't succeeded in a while, the rate will stay listed but show a 'stale' badge.
• How the site makes money. Some links here are referral links: if you join a portal through one of these links, that portal may pay us a referral bonus. It never changes the rates we show or how we rank them. Here's the full disclosure.

This isn't the only thing I've built for this hobby. If you've earned a pile of miles and aren't sure what they're worth, CBYS' sister site PointAuctions.com tracks auctions across airline and hotel loyalty programs. This site is the earning side; that one is the spending side.

Where to start

If you want to kick the tires: search for a store you buy from and check its page, or see which stores are at their highest yet. If something looks wrong - be it a rate that's off or a portal that's missing - tell me. I read all messages.

And if you'd rather I just email you the interesting stuff each week, that's what the newsletter is for: tips, tricks, and the week's most interesting portal moves, one email each weekend.