Best Payment Processors in the UK for SaaS, AI and Online Businesses (2026): Fees, Pros & Cons
The UK payment landscape in 2026 is defined by the maturity of Open Banking (Pay by Bank) and the shift toward Merchant of Record (MoR) models for software companies. Here are the best platforms to choose from.
Product
Choosing a payment provider in the UK is no longer just about finding the lowest transaction fee. Businesses also need to consider international card charges, UK VAT, global tax compliance, subscriptions, usage-based billing, Open Banking, and how easily the platform connects with tools such as Xero and FreeAgent.
This guide compares the leading UK payment gateways and Merchant of Record platforms in 2026, including their fees, strengths, limitations, and the types of businesses they are best suited for.
1. Stripe (UK)
Stripe remains the dominant force for UK tech businesses. In 2026, it will have fully integrated Variable Recurring Payments (VRP), allowing UK businesses to replace traditional Direct Debits with faster, Open Banking-powered alternatives.
Best For: SaaS, tech startups, and developers.
Indicative Fees:
- UK Cards: 1.5% + 20p.
- EEA Cards: 2.5% + 20p.
- International: 3.25% + 20p.
Pros: World-class API; seamless 3D Secure 2.0 handling; excellent subscription management.
Cons: No phone support for smaller accounts; automated account freezes can be a “black box.”
2. Revolut Business
Revolut has transitioned from a “challenger bank” to a top-tier payment processor. In 2026, its Revolut Pay feature is a major competitor to PayPal in the UK, offering significantly lower fees for its 10M+ UK users.
Best For: Cost-conscious SMEs and companies with heavy multi-currency needs.
Indicative Fees:
Consumer UK/EEA Cards: 1% + £0.20.
International/Commercial: 2.8% + £0.20.
Pros: Funds land instantly in your Revolut Business account; excellent FX rates for international payouts.
Cons: Best rates are locked behind monthly “Grow” or “Scale” plans (£30–£90/mo).
3. Kelviq (Merchant of Record)
Kelviq is built for UK-based AI startups, SaaS companies, and digital product sellers that want to sell globally without managing VAT, sales tax, billing, and compliance themselves.
Unlike a standard payment gateway, Kelviq acts as the Merchant of Record. This means Kelviq handles customer payments, UK VAT, global tax collection, invoices, refunds, and compliance, then sends you a clean payout.
Best For: AI startups, digital product sellers, and SaaS companies scaling globally without an in-house tax team.
Indicative Fees: Flat 3.9% + 40¢ (per transaction).
Pros:
UK VAT and global tax handling: Kelviq calculates, collects, and remits VAT, GST, and sales tax where required.
Built for AI and agents: Supports agent runs, API calls, tokens, credits, top-ups, subscriptions, and pay-as-you-go pricing.
Real-time access control: Check a customer’s plan, balance, credits, or usage limits before an AI agent or workflow runs.
Less billing infrastructure: Payments, usage billing, entitlements, invoices, and customer access are managed in one platform.
Reduced webhook work: Kelviq’s SDKs help manage feature access, usage reporting, and entitlements directly inside your product.
Cons: Not built for e-commerce or physical products.
4. Mollie
Mollie has successfully exported its “localised” European success to the UK. It is widely praised for having the most user-friendly dashboard for non-technical business owners.
Best For: Small-to-medium e-commerce businesses and growth-stage brands.
Indicative Fees:
- UK Consumer Cards: 1.2% + £0.20.
- Commercial/EEA Cards: 2.9% + £0.20.
Pros: Extremely easy setup; elegant checkout UI; daily payouts at no extra cost.
Cons: Not as feature-rich as Stripe for complex “platform” or marketplace models.
5. Checkout.com
A UK-born unicorn, Checkout.com is the high-performance choice for the UK’s massive fintech and enterprise sector. It is built for businesses that process millions and need granular data to fight “false declines.”
Best For: High-volume e-commerce, fintech, and global marketplaces.
Indicative Fees:
- Custom Interchange++ pricing based on volume, risk profile, geography, and payment methods
Pros:
- Modular API architecture
- Detailed reporting and payment-performance insights
- Strong local acquiring capabilities
- Enterprise-focused support and customization
Cons:
- Not suitable for small businesses
- Requires more technical resources than SMB-focused payment platforms
6. Square
Square supports Tap to Pay on iPhone, allowing businesses to accept contactless payments without additional hardware.Square supports Tap to Pay on iPhone, allowing businesses to accept contactless payments without additional hardware.
Best For: Omnichannel retail and hospitality.
Indicative Fees:
In-Person: 1.75%.
Online payments: 1.4% + 25p (UK cards)
Pros:
- No monthly fees for standard payment processing
- Well regarded POS hardware and software ecosystem
- Strong omnichannel capabilities
- Supports integrations with e-commerce and social commerce platforms
Cons: Flat-rate pricing can become more expensive than Interchange-plus pricing as transaction volume grows
7. Adyen
Adyen is a leading enterprise payment platform used by many large UK and global brands.
As a licensed financial institution and acquiring partner in many markets, Adyen provides direct acquiring capabilities that can help improve payment performance and authorization rates.
Best For: Large enterprises, multinational retailers, marketplaces, and established global brands.
Indicative Fees:
- Interchange++ pricing with a fixed processing fee
- Custom pricing based on transaction volume, geography, and payment methods
Pros:
- Unified commerce (POS + Online)
- Advanced fraud detection and risk management
- Direct acquiring relationships with major card networks and payment methods
- Strong support for international expansion
Cons:
- Better suited to businesses with significant payment volume
- More complex onboarding and implementation than SMB-focused platforms
8. Worldpay (by FIS)
Worldpay is one of the UK’s largest and most established payment processors.
It combines long-standing payment infrastructure with modern online, in-store, and omnichannel payment capabilities.
Best For: High-volume traditional businesses, enterprise merchants, and regulated industries.
Indicative Fees:
- Pricing varies based on business profile, transaction volume, risk level, and contract terms
- Enterprise merchants typically receive custom tiered pricing
Pros:
- Long-established payment infrastructure and broad market presence
- Wide range of in-store payment and terminal solutions
- Strong support for omnichannel payment acceptance
- Suitable for complex and regulated business environments
Cons:
- Additional fees may apply depending on contract terms and optional services
- Some merchants report longer contract commitments than fintech-focused providers
9. GoCardless
Unlike traditional card processors, GoCardless focuses on bank-to-bank Direct Debit payments, making it a cost-effective choice for subscriptions, invoices, and recurring billing rather than typical ecommerce.
Best For: Subscription businesses, SaaS, memberships, and invoice-based payments
Indicative Fees (UK):
- Standard: 1% + £0.20 per transaction (capped at £4)
- Advanced: 1.25% + £0.20 (cap £5)
- Pro: 1.4% + £0.20 (cap £5.60)
- International: 2%–2.4% + £0.20
- High-value fee: +0.3% above £2,000
Enterprise: Custom pricing with volume discounts.
Pros:
- Often cheaper than card payments for recurring billing
- Ideal for subscriptions, instalments, and invoices
- No setup fees
- Strong coverage across UK and European bank networks
Cons:
- Not suitable for instant checkout or traditional ecommerce
- Payments can take several days to clear
- Limited support for card payments
- Advanced features and add-ons may require paid plans or additional fees
The best payment gateway for your UK business depends on what you sell and how you plan to grow. Square and Mollie are strong choices for retail and e-commerce, while Stripe offers flexible payment infrastructure for teams that want to build and manage their own billing stack. For UK-based AI startups, SaaS companies, and digital product sellers expanding globally, Kelviq offers a more complete solution. As your Merchant of Record, Kelviq handles payments, UK VAT, international taxes, subscriptions, usage-based billing, credits, and customer access, allowing your team to focus on building the product instead of managing billing and compliance.
