In the architecture of modern applications, online payments occupy a central position and directly influence the quality of the entire product. This is the foundation without which the user experience can easily fall apart. By 2025 the situation has become even more interesting and more complex. Alongside Apple Pay and Google Pay, local payment methods such as UPI in India, PIX in Brazil, and iDEAL in Europe have come to the forefront, not to mention BNPL services that are now present in almost every online store. For developers this means one thing. Applications must support several providers at once, each with its own rules, APIs, and security requirements.
In this article we will examine how modern payment infrastructure works, why simply following a provider’s integration guide no longer solves the problem, and how the entire architecture can be simplified by using a unified backend layer with OneEntry.
How the online payments market has changed by 2025
Over the past few years online payments have undergone a significant transformation. Several noticeable trends have come to the forefront.
The dominance of digital wallets
In many countries Apple Pay, Google Pay and Samsung Pay have taken over almost the entire mobile payments market, where their share reaches 70–90%. For users this is the most familiar and fastest way to complete a purchase in a single gesture.
The boom of BNPL services
“Buy now, pay later” models are no longer a novelty and have become a standard option in online commerce. Klarna, Affirm, AfterPay and their local counterparts have turned into an essential part of the checkout process.
The growth of local payment methods
The global market continues to fragment: India- UPI, Brazil- PIX, Europe- iDEAL and Giropay, Asia - dozens of local e wallets. Each region sets its own rules, and to successfully launch a product it is necessary to take local specifics into account.
Increased expectations for convenience and speed
A user wants to pay as quickly as they send a message. Fewer steps, no unnecessary information and maximum clarity. No one wants to understand how the transaction works, the only thing that matters is that everything happens instantly.
Key requirements for a payment system in 2025
In 2025 the expectations of users and businesses have grown significantly, and a modern application must handle several tasks at once:
Support a variety of payment methods from cards and digital wallets to local options and BNPL
Operate quickly and reliably, regardless of load
Maintain an intuitive UX, where the user performs only a few actions
Ensure a high level of security and compliance
Process refunds and recurring charges without creating inconsistencies in user data
Taken together these requirements form a serious architectural challenge. Each decision affects development speed, maintainability and the correctness of all processes where even a small failure at the payment step can cost a product the trust of its users.
Security PCI DSS, 3D Secure and tokenization
By 2025 the requirements for securing payment operations have become much stricter. If earlier it was possible to integrate a payment flow “somehow” and hope everything worked, today the rules are clear.
The main restrictions are as follows:
Bank card data must not be processed on the frontend. Any attempt to store or transmit a card number directly is a direct violation of PCI DSS.
An application must comply with PCI DSS if it works with card data, and most teams try to avoid this requirement altogether.
SCA and 3D Secure are mandatory in Europe and several other regions, and without additional confirmation a bank will simply decline the payment.
Recurring charges must be performed only through tokens, not through repeated card entry.
What this means in practice: The frontend must not and cannot execute critical payment logic. Everything related to cards, confirmations and transaction statuses must happen on a secure backend level.
Why integrating multiple providers - this is difficult
Today most companies connect not just one but several payment providers at the same time. On paper this looks simple: “we will add one more payment method”. But in practice everything is much more complicated. The main issues are familiar to anyone who has ever implemented a payment flow:
Each provider has its own SDK: with its own rules, limitations and nuances
Webhook events work differently: with different formats, headers, retry patterns and signature verification rules
Operation logic varies: hold and capture, partial refunds, cancellations and recurring charges
Statuses and errors do not match: so different models must be manually aligned into a single set of values
There is no shared order model: and every integration must be adapted to the internal system
As a result developers assemble a payment system like a Frankenstein structure, from pieces of different APIs with different rules and many workarounds. Maintaining such infrastructure is difficult, expensive and highly risky because any failure in one integration can disrupt the entire process.
Approaches to integrating multiple payment methods
When different payment methods appear in an application, teams usually have three options.
1. Connecting provider SDKs directly on the frontend
At first glance this looks like the fastest option. But behind this “speed” there are serious downsides: security rests almost entirely on the client, there is no way to unify different providers into a single format, most logic must be written manually, and scaling turns into chaos.
Using this approach in 2025 is more of a temporary measure than a working solution.
2. Building your own backend that unifies all providers
With this approach you control the order model, statuses, confirmation logic and webhooks yourself. But there are clear drawbacks: it is long and expensive, maintenance costs are high, PCI DSS compliance is required, and every new integration becomes a separate project. This can be a workable solution for companies that have large teams and the resources to build their own payment infrastructure.
3. Using a unified platform that takes over the payment logic (for example, OneEntry)
When multiple integrations appear, it becomes necessary to maintain a stable architecture: unified statuses, webhook processing, correct order updates and secure handling of cards. A unified backend layer solves these challenges systematically:
Unified order and status model - no need to manually bring Stripe, PayPal and local banks to a shared format
Unified API for all payments - the frontend uses a single method regardless of the provider
Centralized webhook handling - the platform itself receives, validates and synchronizes events
Ready backend payment logic - hold, capture, refunds and recurring charges work according to shared rules
Security and compliance - card data and tokens are processed in a secure environment without frontend involvement
In essence, instead of maintaining many fragmented integrations and their own complex payment logic, the team receives a ready backend layer that takes over the heavy part of the architecture and frees resources for working on the product and its interface.
Working with webhooks and transaction confirmation
In real projects the frontend can never reliably determine whether a payment has succeeded or not. The only source of truth - this is the webhook that the payment provider sends after processing the transaction.
The typical process looks like this:
- The user initiates the payment and the frontend sends a request
- The provider receives the transaction and begins processing it
- After that the provider sends a webhook and the backend records the received status
- The backend updates the order according to this status
- The frontend simply requests the final state and displays it to the user
The problem is that Stripe, PayPal, banks and BNPL services all have different sets of webhook events and statuses. For the system to work correctly all of this heterogeneous data must be unified into a single format and a shared order model.
Recurring payments, refunds and cancellations
Recurring charges, refunds and payment cancellations are scenarios that in practice turn out to be much more complex than simply “paying for an order”. Here everything depends on many factors: on how the card is tokenized, on the rules of the issuing bank, on the internal statuses of a specific payment provider, on the customer’s country and currency. Because of this developers often have to write dozens of manual handlers: checking statuses, processing errors, running cron jobs, resolving discrepancies between providers and their own order model.
For this reason more and more companies are moving to platform solutions that take this complex logic on themselves and eliminate the need for constant manual support.
How OneEntry simplifies the integration of payment systems
OneEntry serves as a unified backend layer that takes over all complex payment logic - from connecting providers to handling webhook events. This allows the team to avoid manually assembling infrastructure and to work according to a single, predictable approach. This is what the platform provides:
• Connecting any payment providers
• Managing payment accounts in one place
• Centralized processing of webhooks and transaction statuses
• Synchronizing order statuses regardless of the event source
• Storing and managing payment methods, including tokens
• A unified API for the frontend that works the same for all providers
• Integrations through the Integrations module -for custom or local providers
As a result frontend developers do not need to dive into payment backend architecture. All complex processes remain inside the platform, and on the client side the only tasks are working with UX and displaying results.
OneEntry documentation for working with payments
To avoid limiting this article to theory, here are links to the official OneEntry documentation that help quickly understand specific scenarios and implement payments in a real project.
Connecting payment providers: https://doc.oneentry.cloud/docs/payments/accounts
Payment logic and statuses: https://doc.oneentry.cloud/docs/payments/statuses
Example of a custom PayPal integration: https://doc.oneentry.cloud/docs/integrations/paypal-example
Using Stripe in OneEntry: https://doc.oneentry.cloud/docs/payments/stripe
Practical example: Stripe + PayPal + a local bank through OneEntry
Let us look at how several payment providers work together when combined with OneEntry.
User → Frontend → OneEntry API → Payment provider → Webhook → OneEntry updates the order → Frontend receives the status
To implement such a scenario it is enough to follow several steps:
- Connect payment accounts in the OneEntry admin panel The Payments → Accounts section. Several providers can be added there as well.
- Configure payment methods and currencies The platform supports different combinations - from standard cards to local solutions.
- Configure webhooks Stripe and PayPal send events directly to OneEntry, and the system processes updates automatically.
- Use the OneEntry SDK on the frontend The frontend calls a single payment method without caring through which provider the transaction will go.
- Display order statuses in the UI The client side simply requests the current order state through the SDK - all synchronization logic happens inside the platform.
We see how the landscape of digital payments is becoming more complex, and we understand the pressure this creates for developers and companies. Our team has built a solution that removes routine work, reduces risks and gives teams the ability to create truly modern applications without unnecessary barriers. If teams can spend less time on infrastructure and more on the product, it means we are moving in the right direction.
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