Chances are, if you are reading this article, you are comparing Stripe, Adyen, and PayPal (Braintree) on fees, payout timing, and how quickly you can ship the integration. And that would be reasonable.
But the security outcome is shaped earlier than most teams think. A payment processor protects card data once it enters its fields and systems. The transaction begins on your checkout page, inside a browser that is also running analytics, tag managers, A/B tests, support widgets, and third-party scripts. That front-end environment is where implementation choices matter, and where PCI expectations increasingly concentrate.
We want to help you understand where each processor thrives, what you need to configure, how your integration affects PCI scope, and what it takes to maintain control over what runs on your payment pages over time.
What you’ll learn?
- How Stripe, Adyen, and PayPal (Braintree) differ in merchant security responsibilities by integration path, including what you must configure and protect to keep card data out of your environment.
- How those integration choices affect PCI scope in practice, and what PCI DSS 4.0.1 still requires from you on payment pages, especially 6.4.3 script authorization and inventory, and 11.6.1 change detection.
- Why client-side monitoring is the shared requirement across all processors, and how PaymentGuard AI helps you maintain visibility, detect drift, and produce audit-ready evidence without changing your payment flow.
What Stripe, Adyen, and PayPal (Braintree) provide
All three processors give you a secure, PCI Level 1 payment processing environment. Once card data is handed off through their approved integrations, they handle encrypted transmission, tokenization, and downstream processing inside their own certified systems. That means sensitive card details are replaced with tokens or nonces, and so you do not need to store raw card numbers.
They also bring processor-side fraud controls into the stack, such as Stripe Radar and PayPal’s AVS and CVV checks (via Braintree) with optional add-ons like Kount. Secure APIs, strong transport encryption, and recurring compliance audits are standard across all three.
So if you are asking whether Stripe, Adyen, and PayPal (Braintree) can process payments securely, the answer is yes.
Here’s what they don’t do
They don’t handle anything that happens before the processor ever sees the transaction. Your checkout page still runs inside a browser, alongside analytics, tag managers, A/B tests, support widgets, and other third-party scripts. Those scripts execute in your environment, not the processor’s. None of these providers monitor or govern what else loads on your payment pages, and they do not audit your site for unauthorized client-side changes.
And that matters because PCI DSS 4.0.1 expectations increasingly require merchants to maintain an inventory of scripts that run on payment pages and to detect unauthorized modifications. The processor secures what happens after data enters their systems. You are responsible for the page and the code that initiates the payment.
From baseline to differences
With that baseline in place, the differences come down to integration choices and the security work they shift back onto you. Stripe is a good place to start because it offers the widest range of web integration paths, and those options directly affect how you implement controls, reduce PCI scope, and maintain ongoing assurance.
Using Stripe securely as a merchant
Stripe is often chosen because it offers multiple ways to integrate payments. You can use Stripe.js with Elements, Stripe Checkout, Payment Links, or go deeper with server-side APIs. The security responsibilities shift based on the option you select. With Elements and Checkout, card data is designed to flow directly to Stripe so your systems never handle raw PANs. That can reduce PCI scope, but only when the integration is implemented exactly as intended.
To keep the implementation secure, you do not collect raw card data in your own forms.
You serve checkout over HTTPS with strong TLS, load Stripe.js from Stripe’s CDN so the library stays current, and keep secret API keys out of client-side code and repositories. You also verify webhook signatures so payment events cannot be spoofed, and if you enforce a strict CSP, you explicitly allow Stripe’s required domains so you can keep policy tight without breaking the payment flow.
When you implement those controls correctly, you preserve the handoff to Stripe. And that handoff is what determines how much of PCI stays on your side of the boundary.
How these choices shape your PCI scope
From a PCI standpoint, Elements commonly supports SAQ A-EP and hosted Checkout can support SAQ A. Reduced scope is not zero scope. You still control the payment page environment, including script authorization and inventory under PCI 6.4.3 and change detection under PCI 11.6.1.
Where implementations could drift And because those obligations live in your environment, the most common failures are not exotic attacks. They are small implementation choices that undermine scope reduction and weaken your ability to demonstrate control.
The mistakes that create avoidable exposure tend to look operational: self-hosting Stripe.js, building custom card forms, leaking secret keys, skipping webhook verification, or allowing third-party scripts to expand on checkout without ongoing monitoring.
Stripe tends to optimize for developer flexibility and speed. Adyen is often chosen for enterprise complexity, multi-entity setups, and tighter operational controls, which changes what “secure implementation” looks like.
Using Adyen securely as a merchant
Adyen is typically adopted when payments are only one part of a broader commerce system, especially in organizations managing multiple brands, regions, merchant accounts, or channels. The platform offers several integration paths, including Drop-in and Web Components for hosted payment fields, as well as direct API integrations for teams that need more control.
In most web implementations, Adyen’s components are designed to keep sensitive card data flowing directly to Adyen, which reduces the likelihood that raw PANs ever touch your infrastructure, but that outcome depends on how you configure the client-side boundary.
These controls are what keep the implementation aligned with the reduced-exposure model Adyen is designed to support.
How these choices shape your PCI scope
Because those steps determine where sensitive data can appear, they also determine how much PCI stays in your environment. A properly implemented Drop-in or Components flow can commonly support SAQ A or A-EP, depending on whether your systems can influence payment data capture. Reduced scope is not zero scope.
You still own the payment page environment, including script authorization and inventory under PCI 6.4.3 and change detection under PCI 11.6.1.
So the compliance outcome depends on whether your configured boundaries remain true in production, not just on day one.
Where implementations could drift That is where most Adyen issues arise in practice. They tend to look like configuration and governance drift rather than novel attacks. Misconfigured Allowed Origins can widen where components can be initialized. Credential handling can get messy across multiple merchant accounts and environments.
Webhook validation gets skipped during implementation and never revisited. And third-party scripts expand on checkout pages over time, even though Adyen does not monitor what else runs in the browser.
Adyen security tends to center on consistent configuration and access control at scale. PayPal (Braintree) security tends to center on standardized Hosted Fields or Drop-in patterns, with careful use of customizations that shift responsibility back to you.
Using PayPal (Braintree) securely as a merchant
PayPal (Braintree) is often selected when you want a straightforward card acceptance flow, strong PayPal adjacency, and an integration model that limits how often merchants accidentally handle raw card data. Most teams implement Braintree through Drop-in UI or Hosted Fields, which are designed to keep sensitive payment capture inside Braintree-controlled components rather than inside your own forms.
You can still build more custom experiences through SDKs and server APIs, but the security goal remains the same: preserve a clean handoff so card data is tokenized and processed by Braintree’s certified environment, not absorbed into your application stack.
To keep that handoff intact, you implement Drop-in UI or Hosted Fields as documented and serve checkout over HTTPS with strong TLS. You secure credentials across environments, keeping private keys strictly server-side and using client tokens for front-end initialization. You also verify webhook events so payment and subscription notifications cannot be spoofed, and you keep the Braintree SDK current to avoid running outdated client-side code.
As your checkout evolves, you treat third-party scripts on payment pages as part of the payment surface, because PayPal (Braintree) does not monitor what else runs in the browser. These controls are what keep a “simple integration” from quietly turning into a wider exposure model.
How these choices shape your PCI scope
Because Hosted Fields and Drop-in keep raw card capture out of your infrastructure, Braintree integrations commonly support SAQ A. Reduced scope is not zero scope. You still own the payment page environment, including script authorization and inventory under PCI 6.4.3 and change detection under PCI 11.6.1.
So the compliance outcome depends on whether your checkout page remains controlled over time, not just on whether you chose Hosted Fields on day one.
Where implementations could drift The issues tend to be operational. Teams attempt custom card forms instead of Hosted Fields, which pulls card data back into the merchant environment. Private keys leak into client-side code or repositories during development. Webhook verification is skipped because the integration “works” without it.
And third-party scripts expand on checkout pages through marketing tools or tag managers, even though those scripts run beside the payment flow and are not monitored by Braintree.
At this point, the pattern is clear. Each processor can keep card data out of your systems, but the day-to-day security work shifts depending on how the integration is configured and maintained.
What changes for you across Stripe, Adyen, and PayPal (Braintree)
The table below summarizes where merchant responsibilities diverge across integration, credentials, maintenance, and the controls you still own on the payment page.
| Security aspect | Stripe | Adyen | PayPal (Braintree) |
| Integration surface | Generally quick to implement | More configuration-heavy, built for scale | Standardized patterns, typically simplest |
| Credentials model | Publishable key client-side, secret key server-side | Client key plus server API key, plus allowed origins | Public key, private key, merchant ID, front-end client token |
| PCI scope outcome | Often SAQ A-EP, SAQ A with hosted Checkout | Often SAQ A or A-EP depending on flow | Commonly SAQ A with Hosted Fields or Drop-in |
| Library maintenance | Stripe.js hosted and auto-updated via CDN | Versioned libraries, merchant updates periodically | Versioned SDK, updates depend on hosting or bundling |
| Webhook verification | Signature header verification required | HMAC signature verification required | SDK-based verification of payload and signature |
| CSP considerations | Allow Stripe domains for scripts and frames | Allow Adyen domains, include 3DS flows | Allow Braintree and PayPal domains for frames and scripts |
| What you still monitor | Page scripts, third-party tags, page integrity | Same, plus domain and origin configuration drift | Same, especially third-party scripts around iframes |
| Common failure modes | Self-hosting Stripe.js, leaking secret keys, script sprawl | Loose origins, credential sprawl, skipped HMAC checks | Leaked private keys, skipped webhook checks, script sprawl |
The client-side responsibilities processors leave with you
Stripe, Adyen, and PayPal (Braintree) can secure payment data once it enters their systems, but they all leave the same browser layer responsibilities with the merchant. Your checkout page runs inside the customer’s browser, alongside analytics, chat widgets, tag managers, A/B tests, and other third-party services that execute in your domain.
Because that code is not hosted or controlled by the processor, none of these providers monitor which scripts are present, whether they change, or whether a new script starts collecting data it should not.
What you still have to monitor on payment pages
You are responsible for governing third-party scripts, maintaining an inventory of what is authorized, and detecting unauthorized code or page modifications. In PCI DSS 4.0 terms, this maps directly to script authorization and inventory under 6.4.3 and change detection under 11.6.1.
Why processors do not cover it
This is outside their architectural scope. The browser session runs in your environment, requires full page context, and can change through tag managers and vendor updates that the processor cannot see.
A real-world failure mode
A merchant can implement Stripe Elements correctly, but an analytics script on the same checkout page can begin collecting form data. Stripe remains secure, but the payment page is now out of compliance with 6.4.3, and the merchant owns that outcome.
Once you accept that processors do not govern the browser layer, the question arises: how do you continuously know what is running on your payment pages, and how do you prove you would catch unauthorized change?
How PaymentGuard AI strengthens Stripe, Adyen, and PayPal (Braintree) at the point of checkout
PaymentGuard AI complements any processor by focusing on the part of the payment experience that still belongs to you: the code that executes in the customer’s browser. It does not replace Stripe, Adyen, or PayPal (Braintree), and it does not interfere with their payment fields. Instead, it gives you continuous visibility into what actually runs on your checkout pages as your site evolves.
Continuous visibility into what executes
PaymentGuard AI discovers every script present on payment pages, including third-party and downstream dependencies, and maintains a living inventory. That inventory becomes a practical way to support PCI 6.4.3 because it helps you keep script authorization tied to business purpose.
Change detection you can act on
Because the browser surface can change outside release cycles, PaymentGuard AI watches for drift in real time. When a new script appears, an existing script changes, or a security-relevant configuration is modified, it flags the event and produces an audit trail that supports PCI 11.6.1.
Evidence that holds up under scrutiny
The value is not only detection. It is defensibility. When an assessor asks how you control scripts on payment pages, you can show what ran, what changed, when it changed, and what your team did in response. The end state is end-to-end coverage: your processor secures the transaction after handoff, and PaymentGuard AI helps you continuously control and evidence the payment page environment that initiates it.
Where secure processing ends and your responsibility begins
Stripe, Adyen, and PayPal (Braintree) are all secure processors, and each can keep card data inside a PCI Level 1 environment once the payment flow is implemented correctly. The practical difference is how their integration choices shift security work back onto you.
If you use Elements, Drop-in, or Hosted Fields as intended, you can reduce PCI scope because raw card data stays out of your systems. But the checkout experience still runs on your site, in the browser, alongside the scripts and third-party services you choose to load.
None of the processors monitor that client-side environment for you, and PCI DSS 4.0 still expects you to prove control there through script authorization and inventory under 6.4.3 and change detection under 11.6.1.
So choose a processor based on business fit like pricing, payment methods, and geography, and then operationalize client-side control as part of the decision. Schedule a demo to see how PaymentGuard AI monitors checkout page scripts across any processor, detects unauthorized changes, and produces PCI-ready evidence for 6.4.3 and 11.6.1.
