The 5 Best Payment Service Providers for Online Shops (2026)

If you manage an online shop, you already know: the e-commerce checkout is a crucial part of your business. It determines whether visitors actually become customers or abandon their purchase due to a payment process that is cumbersome, slow, or appears untrustworthy. 

But which payment service provider is right for your business? What are the differences between traditional Payment Service Providers (PSPs) and well-known payment brands such as PayPal or Klarna? And what should you pay particular attention to when choosing, so your conversion rate increases while keeping costs under control? 

In this article, we explain

• What a payment service provider (PSP) is 
• What to watch for when choosing a provider 
• How the five leading payment providers compare 
• Practical tips for your decision 

Payment Service Providers Explained – What Types Are There?

What is a Payment Service Provider?

A payment service provider is a company that handles payment processing on your behalf. They ensure your customers' payments are transferred securely, quickly, and compliantly from their account or card to your merchant account.

A payment service provider handles: 

• The technical integration of payment methods (e.g. credit card, SEPA, wallets) 
• Secure processing and authorisation of each payment 
• Fraud prevention and management of chargebacks 
• Reporting and analysis of your takings 

What is a Payment Service Provider (PSP)?

A PSP is a technology platform that enables the integration of various payment methods via a single interface.

Think of the PSP as the payment backbone of your shop: It offers all relevant payment methods from one source – fully integrated technically, with management, reporting, security, and risk tools. 

A PSP typically supports: 

• Credit cards (Visa, Mastercard, Diners/Discover, Amex) 
• Wallets such as Apple Pay, Google Pay, PayPal 
• SEPA Direct Debit 
• Invoice or instalment purchase (often via partners) 
• Payments in multiple currencies 
• POS integration for in-store commerce 

So, a PSP is not just a payment processor – it forms the technological basis for your entire payment stack. 

PayPal & Klarna – Specialists, but Not Full PSP Replacements

Many merchants wonder whether providers like PayPal or Klarna can replace a PSP. The answer: they can complement, but not fully replace, a PSP. 

PayPal is a wallet: Customers pay quickly and easily using their PayPal account. 
Klarna has also evolved into a wallet in recent years: with its own app and account, users can pay both online and in-store, manage purchases, and choose from various payment options. 

Both solutions can be integrated directly or via a Payment Service Provider to offer your customers a comprehensive range of payment options. 

Key Criteria When Selecting a Payment Service Provider

Before making your choice, define your requirements clearly. The following checklist will assist you: 

1. Target Audience & Customer Behaviour

Who are your main customers?

• Younger customers expect wallets such as Apple Pay, Google Pay, PayPal, or Klarna 
• Business customers often prefer invoice, SEPA, or card payments 
• Millennials and older customers frequently opt for invoice or instalment payments (BNPL) 

2. Payment Methods

• Which payment methods are in demand in your target markets? 
• Do you sell only online or also in physical stores? 

3. Region

In the DACH region, invoice and instalment payments (BNPL) are particularly popular – sometimes accounting for over 50% of payment volume. 

The more familiar payment options you offer, the higher your conversion rate.

4. Fees & Pricing Structure

Fees typically consist of:

• a percentage of the transaction amount 
• a fixed fee per transaction 
• possibly monthly or setup costs 

What is your payment volume? Fixed fees impact small transactions more. 
For high volumes, Interchange++ may prove advantageous. 

5. Technical Integration

• Are plugins available for e-commerce systems like Shopify, PlentyONE, Shopware, etc.? 
• Do you need an API for customised solutions? 
• Are payment pages optimised for mobile checkout? 

6. Internationalisation

If you sell internationally, you’ll need:

• Local payment methods 
• Support for multiple currencies 
• International routing 

7. Support & Service

Support is vital, especially for high turnover.

• Is there a dedicated account manager? 
• Does support operate in your language? 
• What is the response time? 

A Detailed Look at the Five Leading Payment Service Providers

Unzer

Unzer has a strong foothold among mid-sized European businesses and is especially suited to SMEs. With its market-leading in-house solution for risk-free invoice and instalment purchasing, Unzer offers a complete package from a single provider.

• Specialist for invoice & instalment payments (BNPL) 
• "UnzerOne" platform enables omnichannel payments and business insights 
• All major payment types available via one interface 
• Over 90,000 merchants across Europe 

Adyen

Adyen is globally oriented and an ideal solution for larger enterprises.

• 100+ local payment methods 
• Interchange++ pricing model 
• Data-driven and highly scalable 

Stripe

Stripe is particularly suitable for SaaS businesses or digital companies with technical expertise.

• API-first solution 
• Subscription management and digital business models 
• Supports over 135 currencies 

Mollie

Mollie is ideal for smaller online shops focused on quick implementation.

• Simple set-up 
• No minimum contract period 
• Transparent fees 

Nexi Germany

The Nexi Group, bolstered by the acquisition of Concardis, has a strong presence in the DACH region and is established with retailers requiring POS solutions.

• Traditional PSP in DACH 
• Focus on terminal business & card acquiring 
• Integration with in-store and POS systems 

Overview: Target Groups, Omnichannel Capability, Internationalisation & Support Structure

Payment Methods in Detail

Trends 2026 – What to Watch

• Digital payments will continue to increase, with cash usage, especially in retail, steadily declining. 
• Buy now, pay later (BNPL) will continue to grow, particularly in B2C, opening new revenue streams via invoice and instalment purchases. 
• Unified commerce will become the standard. Customers will expect seamless experiences across all channels. 
• Payment data will become a strategic asset, e.g. for marketing, segmentation and personalised offers. 

Conclusion – Choosing the Right Payment Provider Pays Off

Selecting the right payment provider for your online shop is more than just a technical detail: it fundamentally affects your conversion rate, costs, liquidity, scalability, and customer satisfaction. Payment is not a secondary matter – it is a core element of your business strategy.

The smoother your checkout, the broader your payment options, and the more trustworthy the process appears, the higher your completion rate. Missing payment options, lengthy loading times, or a sense of insecurity lead to abandoned shopping carts and measurable loss of turnover. 

A quality payment service provider helps you to: 

• Reduce abandoned purchases (by offering relevant payment options) 
• Expand into international markets (local methods, multiple currencies) 
• Minimise risk (integrated fraud prevention) 
• Decrease your workload (automated billing/reporting) 
• Make strategic decisions (data analytics) 

As your business grows, the importance of scalable payment infrastructure becomes evident. A currently cheap provider may soon reach its limits – and an enterprise set-up may be unnecessarily complex for small shops today. The key is choosing a provider that matches your current business model and growth strategy. 

Payment providers are not simply a cost, but a lever for sustainable growth. Ultimately, a reliable, transparent, and customer-friendly payment process builds trust – one of the most valuable currencies in e-commerce. 

Frequently Asked Questions on Payment Service Providers

Which payment service providers are there?

Well-known full-service Payment Service Providers (PSPs) include Unzer, Adyen, Stripe, Mollie, and Nexi (including Concardis). These providers bundle several payment types such as credit card, direct debit, wallets, and invoice purchase into a single technical infrastructure, handling settlement, fraud prevention, and payouts to merchants. In addition, there are specialised payment providers like PayPal or Klarna, who primarily offer their own payment methods and are often integrated alongside a PSP. 

How much does a payment service provider cost?

The costs usually range between 1.3% and 2.9% per transaction, plus a fixed fee of approximately €0.10 to €0.35 per payment. Additional setup fees, monthly basic fees, or costs for chargebacks may also apply. 

Actual conditions depend heavily on your business model, industry, and transaction volume. While some providers publish fixed pricing models, others work with individual offers for merchants with higher revenues. 

Which payment methods should I offer in my online shop?

In Germany, you should at least offer credit card, PayPal, and purchase on account. Depending on your target group, wallets such as Apple Pay and Google Pay are also relevant. 

The choice of payment methods directly influences your conversion rate. Younger target groups often prefer wallet solutions, whereas for higher shopping cart values, invoice or instalment payments are particularly important. A PSP such as Unzer enables these payment methods to be bundled via a single technical interface. 

Which “Buy Now, Pay Later” (BNPL) payment providers are there?

Buy Now, Pay Later is offered by Klarna, PayPal, and Unzer, among others. This refers to purchase on account or instalment payments with a payment deadline. 

The main difference lies in how the solution is implemented: 

Klarna and PayPal appear as visible brands during checkout. The payment process runs through their own interface, including a login or app environment. This can foster trust, but it also means customer data partly remain in the provider’s ecosystem and cross-selling or upselling offers may be displayed. 

Unzer, on the other hand, offers BNPL as a white-label solution. This means invoice or instalment purchase can be fully integrated into your shop’s design, without any external brand presence at checkout. As a result, the user experience remains consistent, your brand stands at the forefront, and you retain greater data sovereignty. Additionally, the solution is flexibly customisable – for example, regarding checkout design and risk settings. Consumers neither need their own accounts nor apps. 

Which German payment providers are there for online shops?

Unzer is headquartered in Berlin and is one of the leading full-service payment service providers, especially for SMEs. Unzer supports all common payment methods, including credit cards (Visa, Mastercard), direct debit, instant transfers, PayPal, Apple Pay, Google Pay, as well as local payment methods. In addition, Unzer offers flexible white-label-capable solutions for invoice and instalment purchases (BNPL), including risk assumption. Via the Unzer platform, merchants can manage payments in both their online shop and physical store through the integrated “Unzer One” platform. 

The Nexi Group has a strong operational presence in Germany through its acquisition of Concardis. Historically, its focus has been more on in-store trade. 

Can I combine several payment service providers?

Yes, technically it is possible to use multiple providers in parallel. Many merchants combine a main PSP with specialised providers. However, this increases administrative effort, as multiple contracts, settlements, and technical interfaces must be managed. 

A bundled solution can be more efficient and transparent in the long run. 

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