Klarna Checkout
Klarna Checkout is a complete payment solution where Klarna handles a store's entire checkout.
What detecting Klarna Checkout tells you about a site
Klarna is a buy-now-pay-later and checkout-financing provider, so it appears specifically on commerce and checkout pages as a payment option. The tell is a script from Klarna's JS host plus on-site messaging components that render instalment offers next to prices, and a redirect or hosted widget at payment. Detecting it tells you the merchant sells consumer goods at a price point where deferred payment lifts conversion — fashion, electronics and mid-ticket retail — and that they have integrated a regulated financing partner, which is a non-trivial commercial decision.
Klarna Checkout in a real-world stack
When you find Klarna Checkout, it rarely travels alone. Sits beside a primary payment processor and other BNPL/wallet options (Afterpay, PayPal), within a consumer e-commerce platform.
About
Klarna Checkout is a complete payment solution where Klarna handles a store's entire checkout.
Categories: Payment processors, Buy now pay later
Quick facts
Detection methodology for Payment processors
Payment SDKs identify themselves through their script src URL (`js.stripe.com/v3/`, `www.paypal.com/sdk/js`, `cdn.adyen.com/`) and runtime globals (`Stripe`, `paypal`, `AdyenCheckout`). We surface the exact SDK version via the sourcemap when shipped — Stripe Elements 14.x vs 5.x, PayPal Checkout v5 vs v6 — which matters for security and compliance work much more than the categorical 'they use Stripe' answer.
How we detect Klarna Checkout
Sourcemap Explorer carries 7 fingerprint signals for Klarna Checkout, spread across 5 channels — response header, cookie, javascript global, script src url and dom selector. The exact patterns are listed below, and you can replay each one in Chrome DevTools to confirm a match by hand.
Each signal alone is rarely conclusive — Sourcemap Explorer cross-references all of them and weights by confidence. You can reproduce any of these checks yourself in Chrome DevTools.
Server-side fingerprint: the response header reveals the technology behind the page. Visible in DevTools → Network → response headers.
content-security-policy: \.klarna(?:cdn|services)\.(?:net|com)
Cookies set by the platform. Visible in DevTools → Application → Cookies.
ku1-sid
ku1-vid
Window-level global the technology installs on page. Reproducible by typing the path into the DevTools console.
window.KlarnaOnsiteService
window._klarnaCheckout
Script URL pattern. Typically a CDN host or chunk path that ships with the technology.
\.klarnaservices\.com/lib\.js
A DOM selector that only this technology's pages render. Verified at runtime by the content script.
[aria-labelledby='pi-klarna']
FAQ
How do I check if a website is using Klarna Checkout?
Open the page in Chrome, click the Sourcemap Explorer toolbar icon, and read the Stack tab. Klarna Checkout's specific fingerprints here are response header, cookie, javascript global, script src url and dom selector, and the popup flags Klarna Checkout whenever any combination of them is found. The same checks can be reproduced manually in DevTools — see the "How we detect" section above.
What Klarna Checkout version can Sourcemap Explorer detect?
Klarna Checkout ships as a hosted payment processors rather than a bundled npm package, so version-specific detection isn't always possible. Where the platform leaks a version in response headers (`X-Powered-By`, `Server`, generator meta tags) we surface it; otherwise we report presence only.
Is Klarna Checkout a SaaS or self-hosted?
Klarna Checkout is offered as a hosted SaaS product. Detection runs against the JavaScript SDK or asset-URL fingerprints the platform ships into pages.
How much does Klarna Checkout cost?
Klarna Checkout's pricing model is documented as: payg, low, recurring. Detection is independent of the pricing tier — Sourcemap Explorer flags the technology by its fingerprints, regardless of which paid plan a site is on. See the official site for the current pricing page.
Where can I read more about Klarna Checkout?
Official site: https://www.klarna.com/international/. For Sourcemap Explorer's detection guide, see the deep-dive link below or the related guides in the cross-link section.
Keep reading on Sourcemap Explorer
Practical guides
Alternative tools
Detected by Sourcemap Explorer
Open the popup on any page running Klarna Checkoutand you'll see the exact version pulled from the bundled package.json when sourcemaps are exposed.