I Scanned 100 SaaS Checkout Pages — Here's What Was Broken

We built a free checkout scanner. So we used it. 100 SaaS products, one afternoon, a notebook full of results that were more alarming than we expected.

We scanned the checkout or pricing pages of 100 publicly accessible SaaS products across categories: developer tools, fintech, HR software, e-commerce platforms, B2B SaaS, and consumer apps. Every product had an active marketing site and an active checkout or subscription flow. The scan ran from 3 global regions: India (Mumbai), United Kingdom (London), and USA (N. Virginia).

Methodology

Each product was scanned using PingSLA's checkout flow checker — the same engine that powers the free Checkout Defender tool. The scanner opens a real headless Chromium browser, navigates to the checkout or payment page, monitors JavaScript execution, records all network requests and responses, captures screenshots, and classifies the result.

Classification criteria:

• Pass: Payment widget renders correctly, no JavaScript errors, all third-party SDK requests succeed across all 3 regions
• Warning: Widget renders but with degraded performance (>3s load time), or minor errors that don't prevent payment
• Silent failure: Payment widget does not render due to JavaScript error, CDN failure, or rendering issue — server still returns 200 OK
• Hard failure: Checkout page returns error status, white screen, or unrecoverable error

We are not naming specific companies. The goal is to document failure patterns, not embarrass anyone.

The Results

77 out of 100 passed cleanly. That's genuinely good. Most SaaS teams are doing the basics correctly.

But 23% had measurable issues. 8% had failures that a standard uptime monitor would never catch — because the server was returning 200 OK the entire time. Those 8 products almost certainly had their uptime dashboards showing 100% while real users were unable to pay.

What Was Actually Breaking

Issue 1: CSP Blocking Third-Party SDKs (4 products)

The most technically sophisticated failure we found. Four products had Content Security Policy headers strict enough to block Stripe's JavaScript from loading. In all four cases, a recent security hardening effort had added script-src directives without explicitly whitelisting the payment provider's CDN domains.

The products affected ranged from a funded B2B SaaS (clear engineering team) to a bootstrapped developer tool. None of them showed any monitoring alerts. Their servers returned 200 OK. The CSP violation was purely client-side and completely invisible to server-side monitoring.

What it looked like in production: Checkout page loaded normally. Payment section showed a loading spinner indefinitely. No user-visible error message.

Why uptime monitors missed it: The HTTP response was valid. The CSP header itself returned fine. The browser's enforcement of the CSP — which blocked Stripe's script from executing — happened entirely on the client.

Issue 2: Mobile-Only Failures (3 products)

Three products had checkout flows that worked correctly on desktop viewport but failed on mobile. In two cases, the payment widget rendered but was overlapped by a sticky mobile navigation bar, making it impossible to interact with the payment form. In one case, the Razorpay checkout popup was blocked entirely on mobile — the button trigger didn't meet mobile browser requirements for popup invocation.

Why this matters: 60–70% of traffic for consumer-facing SaaS is mobile. A mobile-only checkout failure is effectively a majority-traffic failure — just hidden behind desktop-passing monitor checks.

What it looked like: Desktop checkout: fine. Mobile viewport test: payment button unreachable or popup blocked.

Issue 3: Region-Specific CDN Failures (2 products)

Two products had checkout failures only from the India probe location. The payment SDK loaded fine from USA and UK probes but timed out from Mumbai. In one case, the Razorpay CDN edge node was experiencing elevated latency causing the SDK script to time out before rendering. In the other, a regional Stripe CDN routing issue caused the Stripe.js request to fail from the ap-south-1 AWS region.

Both products had zero alerts in their monitoring dashboards. For users in India — a significant market for both products — checkout was broken.

This is the failure mode that hits Indian SaaS companies hardest. Razorpay checkout monitoring from Indian probes is specifically designed to catch this pattern.

Issue 4: Stale Session Tokens (1 product)

One product's checkout failed consistently on the second attempt. The first checkout attempt worked. If a user abandoned checkout and returned to the same URL within the same browser session, the checkout page loaded with an expired session token, causing the payment intent creation to fail silently.

This is a particularly insidious failure because it specifically targets users who tried to buy but hesitated — arguably your most valuable leads.

Issue 5: Currency Switch Breaking Payment Intent (1 product)

One product allowed currency selection on the checkout page. Switching from USD to EUR after the page had loaded caused the Stripe PaymentIntent (created on initial page load) to become invalid for the new currency. The page did not handle this error gracefully, resulting in a silent failure where the "Pay" button did nothing when clicked.

The product passed all automated checks because the scanner didn't trigger the currency switch. Only manual testing revealed this.

What All Passing Sites Had in Common

Looking at the 77 products that passed cleanly, several patterns emerged:

CDN presence in target markets. Products that used multi-region CDNs (Cloudflare, Fastly, AWS CloudFront) with POPs in India and the Middle East consistently passed all 3 regional probes. Products using single-region hosting or limited CDN configurations showed higher failure rates from non-US probes.

CSP configured with payment providers explicitly whitelisted. Passing products had CSP headers that explicitly included https://js.stripe.com, https://checkout.razorpay.com, and similar payment SDK domains in their script-src directives.

Automated checkout monitoring. Of the passing products we could verify through public status pages or engineering blogs, a disproportionate number mentioned synthetic or flow monitoring in their infrastructure stack. This correlation makes intuitive sense: teams that monitor their checkout with real browsers are also more likely to catch the issues before they reach production.

India in the monitoring region set. Products that specifically mentioned monitoring from Indian probe locations (relevant for their user base) showed zero Indian-specific failures.

How to Check Your Own Checkout

Run the free Checkout Defender tool on your own checkout page now. It takes 60 seconds and checks all the failure modes documented in this post: payment widget rendering, JavaScript errors, CDN loading from multiple regions, and mobile viewport.

If you find an issue, the report will tell you exactly what failed, in which region, and what the likely cause is.

For ongoing protection — not just a one-off scan — set up a continuous flow monitor on PingSLA that checks your checkout every minute from all three regions. When the next CDN hiccup happens or a deploy pushes a bad CSP header, you'll know within 60 seconds instead of Monday morning.

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How large was your sample size and is 100 sites statistically significant?

100 sites is enough to identify failure patterns and categories, but not enough to generate industry-wide failure rate statistics. The 6% silent failure rate should be read as directional evidence that silent checkout failures are common and underdetected, not as a precise industry benchmark. A larger study with 500+ products would be needed for statistical significance.

Did you contact the companies with broken checkouts?

We did not contact individual companies. This report is published as a pattern analysis, not a disclosure. If you recognize your product in these failure modes, the free Checkout Defender tool will confirm whether the issue is still present.

Can the checkout scanner test payment flows that require actual credentials?

The free Checkout Defender tool checks whether the payment widget renders and loads correctly — it does not submit actual payment credentials. For testing authenticated checkout flows end-to-end, PingSLA's Pro and Growth plans support multi-step flow monitors with credential injection for test accounts.