Custom Mollie integration development
Appfront builds custom Mollie integrations that connect your webshop, SaaS platform or application to one of Europe's most widely used payment service providers. Using the official Mollie API, we integrate iDEAL, credit cards, recurring payments and 25+ other payment methods, tailored to your checkout, order flow and backend.
What is a Mollie integration?
Mollie is a Dutch payment service provider used by more than 250,000 businesses across Europe to process online payments. The platform supports iDEAL, credit cards, PayPal, Bancontact, SEPA direct debit, Klarna, Apple Pay, Google Pay and dozens of other payment methods, all through a single, well-documented REST API.
A Mollie integration connects that payment infrastructure to your webshop, SaaS platform or own application. Customers pay with their preferred method, transaction status is updated in real time via webhooks, and refunds, chargebacks and reporting flow automatically into your backend or accounting software.
Appfront builds these integrations to measure using the official Mollie API v2. We align the checkout flow, payment methods and backend processing with your specific business model, from simple one-off payments to complex recurring billing and split payments for platforms.
Secure payment processing
Mollie is PCI DSS Level 1 certified. Sensitive card data never touches your servers, as the entire payment flow is handled securely by Mollie's hosted checkout or components.
Multiple payment methods
iDEAL, credit card, PayPal, Bancontact, SEPA, Klarna, Apple Pay, Google Pay and more, through a single API integration. New methods can be activated without code changes.
Via the official REST API
Implementation via the Mollie API v2 with comprehensive documentation, official client libraries and webhook-driven status updates. No scraping or workarounds.
Our process for Mollie integrations
From the initial analysis of your payment flows to a working, tested integration in production. Every step aims for an integration that pays reliably, reports accurately and that your team can understand for themselves.
We map out your payment flows: which methods, which markets, one-off or recurring, and how transactions flow through to your backend and accounts.
We design the integration architecture, configure Mollie API keys and webhooks, and establish error handling and retry logic.
Implementation in your stack with automated tests via the Mollie test environment. You see working builds with real payment flows in sandbox mode.
Controlled go-live with transaction validation, webhook monitoring and real-time alerting. Followed by ongoing management and conversion optimisation.
What a Mollie integration delivers in practice
Every integration is built around your payment processes. Below are the features we most often implement for organisations that want to connect Mollie to their platform.
iDEAL and credit card integration
The core of every Dutch webshop: iDEAL payments and credit card processing via Mollie's hosted checkout or embedded components. Includes 3D Secure authentication and iDEAL 2.0 support for higher conversion.
Recurring payments
Automatic direct debit for subscriptions, memberships or periodic services. Mollie stores mandates securely; your system triggers collections based on contract data via SEPA Direct Debit or credit card without customer interaction.
Webhook-driven status updates
Mollie sends webhooks on every status change: paid, expired, refunded, chargeback. Your application processes these events asynchronously via a queue, so orders, access and administration always stay in sync.
Checkout optimisation
An optimised payment page with the right methods for your audience, pre-selection based on customer location and device, and minimal steps to payment. Aimed at higher conversion and lower cart abandonment.
Refund and chargeback management
Automated handling of refunds and chargebacks. Refunds are created directly via the Mollie API from your admin panel, with automatic forwarding to accounting and customer communication.
Payment reporting
Transaction data from Mollie is combined with order data in custom dashboards or forwarded to tools such as Power BI, Looker Studio or your accounting package. Revenue, conversion rates and payment method breakdowns in one overview.
Who do we build Mollie integrations for?
The complexity of a Mollie integration varies greatly by type of business. A webshop with a standard checkout has different requirements from a SaaS platform with thousands of subscriptions. Four patterns we regularly encounter.
E-commerce webshops
Webshops that need more than a standard WooCommerce or Magento plugin. Think custom checkout flows with payment method pre-selection, one-click reorders for returning customers, or automatic VAT handling per country. Mollie processes the payment, while your backend manages the order flow. Find out more in our custom e-commerce development.
SaaS platforms
Software-as-a-Service businesses that invoice monthly or annually build recurring payments using Mollie mandates. Customers grant permission once, and your platform collects payments automatically each cycle. Includes grace periods, upgrade and downgrade logic, and dunning for failed payments. See also our custom web app development.
Marketplaces & platforms
Platforms that facilitate transactions between buyers and sellers use Mollie's split payments (Mollie Connect). Funds are automatically distributed across multiple recipients, including the platform commission. Appfront builds the onboarding flow, the payments dashboard and the payout logic.
Subscription models
From fitness apps and streaming services to business tools: any company with recurring revenue can use Mollie's subscription flow. We build the full lifecycle (trial, activation, renewal, cancellation), including prorated billing and automatic communication when payment issues arise.
Technology we use
We build Mollie integrations using modern, maintainable stacks. The Mollie API v2 is RESTful and offers official client libraries for the most widely used languages. The exact choice depends on your existing platform, so that your team can continue developing the integration.
Why choose Appfront for your Mollie integration?
Appfront builds payment integrations for a wide range of businesses across the Netherlands, from start-ups launching their first checkout to established platforms processing millions of transactions a year. We always begin with a thorough analysis of your payment flows, target audience and technical architecture.
With every integration, we write clear documentation and make sure your own development team, or any future supplier, understands the integration and can manage it. No black box, but transparent code with clear agreements on monitoring, alerting and further development.
You work with a dedicated technical point of contact who understands both the Mollie API and your business logic. This keeps communication short and speeds up decisions when choices need to be made during the build.
Also explore our wider services in API integrations, e-commerce development and web app development.
- Experience with the full Mollie API: payments, refunds, subscriptions, Connect
- Checkout conversion as a design principle, not an afterthought
- Webhook architecture with queue-based processing and retry logic
- Comprehensive logging and real-time monitoring from day one
- Clear documentation your team can read and manage
- A fixed point of contact, no account managers passed around
- Experience with iDEAL 2.0, recurring payments and split payments
- A way of working tailored to your existing platform and tech stack
Security and privacy in payment integrations
Payment data is sensitive by nature. Mollie is PCI DSS Level 1 certified, the highest standard for payment processing. Your application never handles card details directly; that responsibility lies with Mollie. Appfront builds the integration so that the surrounding data flows are also secure and GDPR-compliant.
Authentication with Mollie runs via API keys with restricted permissions or OAuth 2.0 tokens. Webhooks are verified through signature checks, so your system only processes genuine status updates from Mollie. We document the data flows so that your record of processing activities remains complete.
More about our security approach: information security policy and responsible disclosure policy.
- PCI DSS Level 1 compliant via Mollie (no card data on your servers)
- GDPR-compliant data processing and data minimisation
- Encryption in transit (TLS 1.2+) for all API communication
- Webhook signature verification to prevent spoofing
- Least-privilege API keys and role-based access
- Audit trail for all payment events
- Monitoring and alerting for unusual transaction behaviour
- Documentation for your record of processing activities
Frequently asked questions about Mollie integrations
Answers to the questions we are asked most often about custom Mollie integrations.
A Mollie integration is a technical connection that allows your webshop, SaaS platform or application to process payments via Mollie. Through the Mollie REST API, payment methods such as iDEAL, credit cards, PayPal, Bancontact and Klarna become available in your checkout. Transaction status, refunds and reporting are synchronised automatically.
Mollie supports more than 25 payment methods, including iDEAL, Visa, Mastercard, American Express, PayPal, Bancontact, SEPA Direct Debit, Klarna, Apple Pay, Google Pay and Belfius. Which methods are available depends on your Mollie account, target markets and type of service. During the integration, we configure precisely the methods that are relevant to your customers.
Standard plugins for WooCommerce, Magento or Shopify work well for simple checkouts. A custom integration makes sense when you need specific payment flows, such as split payments for a marketplace, automated recurring billing, dynamic checkout optimisation, or deeper integration with your own backend for order processing and accounting.
A standard checkout integration with the most widely used payment methods can be up and running within a few weeks. More complex implementations, involving recurring payments, split payments, multi-currency or integration with an ERP package, take longer. After an intake conversation, we provide a realistic timeline based on your specific situation.
We work with the official Mollie API v2 and its client libraries for PHP, Python, Node.js and Ruby. We build the integration layer in modern frameworks such as Laravel, Next.js, Django or Express. We process webhooks in an event-driven way using a queue-based architecture. Authentication is handled via Mollie API keys or OAuth 2.0 (Mollie Connect).
Yes. Mollie is PCI DSS Level 1 certified, the highest security standard for payment processing. Credit card details are never processed by your servers; Mollie handles that. We build the integration with TLS encryption, webhook signature verification, minimal API key permissions and GDPR-compliant data processing.
The cost depends on complexity: the number of payment methods, the payment flows you need (one-off, recurring, split), integrations with other systems and the amount of customisation in the checkout experience. Ongoing management and monitoring also factor in. We provide a clear quote following a no-obligation analysis of your situation.
Yes. We regularly take over existing payment integrations, even if they were originally built by another party. We carry out a code review and security audit, document the integration and draw up an improvement plan. Common improvements include better error handling, webhook reliability, checkout conversion optimisation and the addition of new payment methods.
Ready to build your Mollie integration?
Tell us which payment flows you want to achieve, from a simple checkout to complex split payments or recurring billing. A no-obligation first conversation will give you a clear picture of the possibilities within half an hour, along with a realistic estimate of timeline and investment.
Current context (May 2026)
REST architecture has now become the de facto standard for web APIs, based on stateless HTTP requests and resource-oriented URLs, a pattern Roy Fielding defined in his dissertation in 2000.
Source: MDN Web Docs — REST (developer.mozilla.org)