Key takeaways

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• The best SaaS payment solution depends on whether you want to own the merchant relationship or just take payments. Providers that onboard your merchants inside your product and let you set pricing turn payments into revenue; gateways alone do not.
  
• Unipaas is the number one choice for a fully managed payments platform: merchant onboarding, KYB, risk, payouts and disputes run behind your brand, with vertical features like Direct Debit, POS terminals and Tax-Free Childcare built in. The other five providers compared below each suit a narrower profile, from global enterprise to consumer marketplaces.
  
• A fully managed provider gets a platform live in 3 to 6 weeks, against 6 to 12 months to build payments in-house. For vertical SaaS in the UK, that managed layer, with KYB, risk, payouts and disputes handled behind your brand, is usually the deciding factor.
  

The best payment solution for a SaaS platform is the one that lets your merchants take payments inside your software, under your brand, with the compliance and risk work handled by someone else. Every provider below can process a card. Far fewer can onboard your merchants, let you set their pricing and pay you a margin on the volume, and that is the line that separates a payment solution for platforms from a payment gateway.

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This roundup compares six payment software solutions on what a platform actually needs: monetisation, speed of integration, payment method coverage, in-person support and how much of the operational burden they carry.

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Why choosing the right payment solution matters

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Whether you run management software, a SaaS platform or a marketplace, your SaaS payment solution decides how fast merchants activate, how many payments fail and how much of the volume you keep.

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A well-chosen payment solution allows you to:

• Onboard new merchants quickly, inside your own product
  
• Support multiple payment methods: cards, wallets, Direct Debit and bank transfers
  
• Hand compliance and risk management to the provider
  
• Scale with speed and confidence
  

Poor payment infrastructure leads to failed transactions, unhappy customers and churn. For digital-first businesses, payments are a strategic decision as well as an operational one. For more on this shift, see why software platforms must fully embed payments.

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What to look for: key features in modern payment platforms

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Not all payment processing software or online payment gateway providers are created equal. When evaluating a solution, keep these features in mind:

• Monetisation. Turn payments into a revenue stream with branded checkout, flexible pricing and value-added services.
  
• Ease of implementation. Developer-friendly APIs and straightforward workflows that minimise engineering effort.
  
• Quick integration. Fast setup to start onboarding merchants, supporting unified payment methods and recurring billing from day one.
  
• Fully managed. Compliance, fraud protection and risk (PCI DSS, GDPR, AML, PSD2) handled end to end as a service.
  

Platforms that adopt these features improve online payment processing and turn payments into a competitive advantage.

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The six payment solutions for SaaS platforms compared

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Based on functionality, scalability and relevance to digital-first ecosystems, these are the solutions to consider in 2026.

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1. Unipaas

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Unipaas is the best payment solution for management software, marketplaces, and vertical SaaS platforms - with unique advantages for industries like childcare, education, gyms, and field services. The platform is tailored to each vertical, with built-in compliance and flexible merchant onboarding. Unlike generic payment providers, Unipaas goes further by offering go-to-market support to optimise onboarding funnels, accelerate merchant acquisition, and provide platforms with a dedicated success manager.

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Strengths:

• One future-proof stack for all payment needs like cards, wallets, open banking, Direct Debit, a fully managed POS terminal solution and even Tax-Free Childcare.
  
• Simple APIs and native components to speed up implementation and minimise engineering effort.
  
• Handles compliance, onboarding, payouts, risk, support, disputes and reporting, including a dedicated success team.
  

Considerations:

• Not positioned for hobby projects or very small-scale use cases.
  
• Less ideal for offline-only businesses.
  

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2. Adyen for platforms

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Adyen offers a strong online payment gateway built for large enterprises and platforms with complex requirements. Its unified commerce approach supports in-person, online, and mobile payments under one system.

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Strengths:

• Omnichannel support across POS and online merchant experience.
  
• Advanced risk management with fraud prevention and dispute handling built in.
  
• Enterprise-ready and dedicated high-touch support.
  

Considerations:

• Overkill for smaller and medium SaaS platforms
  
• Implementation complexity and higher cost
  

3. PayPal for marketplaces

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PayPal is widely recognised and trusted by consumers, making it a strong option for platforms that rely on instant credibility. Their payment solutions for platforms and marketplaces allow for vendor onboarding, split payments, and integration with PayPal wallets.

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Strengths:

• Global brand recognition that carries consumer trust
  
• Built-in wallet support for PayPal and Venmo
  
• Relatively quick setup designed to enable go-live with minimal overhead.
  

Considerations:

• Limited customisation for complex SaaS platforms
  
• Fees can be high for cross-border transactions
  

4. Airwallex

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Airwallex is a global payment solution that lets you accept payments in more than 160 payment methods across 180 countries. Airwallex allows you to settle payments in the same currency that your customers pay in, saving costly exchange rates. It's easy to open an account with local bank details in Airwallex, without having to go to a bank or complete any complicated paperwork.

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Strengths:

• Low-cost international transfers
  
• Extensive global reach to convert, send, and hold funds
  
• Combining accounts, payments, and more
  

Considerations:

• Limited currency options compared to traditional banks.
  
• Only available for business accounts, excluding sole proprietors.
  

5. Stripe Connect

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Stripe remains one of the most popular payment solutions for platforms and marketplaces. With its powerful APIs, Stripe Connect supports multi-vendor payouts, recurring billing, and global expansion.

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Strengths:

• Developer-friendly APIs
  
• Global coverage with 135+ currencies
  
• Supports subscriptions and on-demand marketplaces
  

Considerations:

• Higher fees compared to some competitors
  
• Complex to customise beyond standard use cases
  

6. Square

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Square is the payments and point-of-sale system many small businesses already use: card readers, terminals and registers, an online store, payment links, invoices and subscriptions, available in the UK, US, Canada, Australia, Ireland, France, Spain and Japan. For software companies it offers a developer platform with Payments, Terminal, Invoices and Subscriptions APIs, OAuth to connect a seller's existing Square account, and an App Marketplace to list an integration.

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Strengths:

• Instant recognition with small merchants, many of whom already take payments on Square hardware.
  
• An App Marketplace that puts a listed integration in front of Square's seller base.
  

Considerations:

• Square sells to the merchant, not the platform: sellers hold their own Square accounts, and a platform connects to them rather than onboarding merchants under its own brand or setting their pricing.
  
• Whether a platform can earn on the volume is not stated on its developer pages, so treat it as an integration rather than a monetisation channel unless Square confirms otherwise.
  

Which payment solution fits your platform?

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Four questions settle it faster than any feature list.

• Who are your merchants? If they are UK or European SMEs in a vertical, such as nurseries, clubs, practices, field service firms, landlords or accountants, they need Direct Debit, in-person payments and vertical features like Tax-Free Childcare, and they expect you, not a payment company, to answer when something goes wrong.
  
• Do you want to earn on the volume? Then the provider has to onboard merchants inside your product and let you set their pricing. A gateway integration cannot do that.
  
• Who runs the operational work? KYB, risk, payouts and disputes are a standing function. Either your team staffs it or the provider does.
  
• How fast do you need to be live? With pre-built onboarding, checkout and dashboard components you brand as your own, the kind Unipaas supplies, a platform is live in 3 to 6 weeks. Most of that time goes on your own screens, not on the payment rails.
  

If your answers are vertical SMEs, yes, the provider, and this quarter, that is the profile Unipaas is built for, and the Stripe Connect alternative page sets out the differences in detail. If your platform is a global enterprise, a consumer marketplace, a cross-border treasury problem, or your merchants already run on Square hardware, the sections above describe which of the other five is built for that.

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How to get started with your preferred payment solution

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Once you have identified the right provider, here is how to move forward:

1. Define your use cases. SaaS subscriptions, one-off payments, or multi-merchant marketplaces all have different needs.
   
2. Evaluate APIs and integration scope. Ensure the solution offers clear and simple developer documentation and fits your tech stack.
   
3. Prioritise compliance. Select a provider that handles regulations and reduces your liability.
   
4. Run a pilot project. Test core flows (onboarding, transactions, payouts) with a subset of users before scaling.
   
5. Monitor and optimise. Use real-time reporting to refine payment flows and vendor experiences.
   

The payment solution you choose sets the ceiling on what payments can earn your platform. Pick the one that lets you own the merchant.

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FAQ

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What is the best payment solution for a SaaS platform?

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The one that lets your merchants take payments inside your software under your brand, with compliance, risk and payouts handled by the provider, and that pays you a margin on the volume. For UK and European vertical SaaS that is a fully managed provider such as Unipaas. Enterprise, consumer marketplace, cross-border and developer-led platforms each have a closer fit, set out above.

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What is a SaaS payment gateway, and is it enough for a platform?

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A payment gateway processes card and wallet payments through an API. On its own it does not onboard your merchants, set their pricing or pay you a share, so a platform that only has a gateway earns little from payments. Platforms that want revenue from payments need embedded payments or PayFac-as-a-Service on top.

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What is SaaS payment processing?

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Payment processing inside a SaaS product: your customers' customers pay by card, wallet, Direct Debit or bank transfer without leaving the software, and the payments are reconciled against the invoice, booking or membership inside the platform. A payment system for SaaS is judged on how well it does that, not on the card rails alone.

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What is the best software for accepting online payments as a platform?

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For a single business, any established payment processor will do. For a platform whose customers are themselves businesses, the best software for accepting online payments is one that embeds into your product: merchants onboard in your UI, pay through your branded checkout, links and invoices, and you keep a margin. Unipaas is built for that model; the other five providers above serve it to differing degrees.

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Which payment providers support multi-merchant payouts?

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Unipaas, Stripe Connect, PayPal for Marketplaces and Adyen for Platforms all support multi-merchant onboarding, KYC and KYB checks and automated payouts. They differ on who runs the onboarding and risk work and on whether it happens inside your product or the provider's. Square works the other way round: your merchants hold their own Square accounts and your software connects to them.

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How quickly can I integrate embedded payments into my platform?

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Three to six weeks with a fully managed provider that supplies pre-built onboarding, checkout and dashboard components, against six to twelve months to build in-house. Most of that time goes on your onboarding journey and reporting screens rather than the payment rails.

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How do SaaS platforms make money from payments?

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By taking a margin on the payment volume their merchants process. Platforms set the structure: flat transaction fees, tiered rates, segment pricing, or payments bundled into a higher subscription tier. That requires a provider that lets you set merchant pricing, which a plain gateway does not.

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Are payment solutions customisable for different platforms?

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Yes. Many solutions are modular, allowing platforms to select only what they need. Embedded-first providers like Unipaas specialise in tailoring flows for specific industries.