Custom integrations for your business systems, without having to start over in two years
We build integrations between your ERP, CRM, e-commerce, payment, shipping, accounting, CMS and identity systems that don't break every time a vendor updates. From simple API integrations to multi-system middleware with audit trails, error handling and monitoring: pragmatic, vendor-independent and honest about what it solves.
Why integrations so often become fragile
An integration set up in two days can, four years later, become a spaghetti architecture nobody dares touch. We are often called in when one integration component has failed and suddenly the whole business grinds to a halt.
Hardcoded credentials and endpoints
The integration never had central configuration. Every vendor change requires a code deployment. Migrating to a new environment is a puzzle.
No audit trail
Who forwarded which order? When did the stock sync last run? When data doesn't match, tracing the cause takes hours of work.
No retry or error handling
A single API call fails and the chain stalls. No dead-letter queue, no retry with backoff, no alert to a person when something keeps happening.
Point-to-point integrated
If a supplier changes their API, your integration has to be adjusted. There is no abstraction layer between your business logic and the external service.
Nobody maintains it
The engineer who built it has left. Documentation is sparse. Bugs are hot-fixed and technical debt piles up.
Performance doesn't scale
The integration worked at 100 orders a day. Now it's 50,000: the batch job runs for six hours, rate limits are hit, and the supplier blocks the IP address.
Integration categories we regularly work in
Below are the domains where Appfront builds integrations. In each category we have ongoing projects, sector experience and concrete pattern libraries.
ERP & accounting
Exact, AFAS, Unit4, Microsoft Dynamics 365, SAP Business One, Snelstart, AccountView, Twinfield. Order, invoice, stock and general ledger integrations with an audit trail.
CRM
Salesforce, HubSpot, Microsoft Dynamics 365 Sales, Pipedrive, Zoho. Lead routing, account sync, opportunity events and activity logging from other systems.
E-commerce
Shopify, Magento, WooCommerce, BigCommerce, Lightspeed, Shopware. Catalogue, stock, order, fulfilment, webhook events and headless storefronts.
Payments & PSP
Mollie, Stripe, Adyen, Buckaroo, Pay., Worldline. Payment initiation, settlement import, recurring billing, refund flows and reconciliation with accounting.
Shipping & fulfilment
PostNL, DHL, DPD, GLS, UPS, Sendcloud, Shipstation. Label generation, tracking events, returns flows and shipment status in the customer portal.
Document automation
PandaDoc, DocuSign, Proposify, Adobe Sign. Template rendering, e-signature flows and archive integrations for quotes, contracts and compliance documents.
Communication & CPaaS
Twilio, MessageBird, Vonage, Pinger. SMS, voice, WhatsApp Business and OTP flows with retry, fallback and compliance logging.
Identity & SSO
Microsoft Entra ID (Azure AD), Okta, Auth0, Google Workspace, Keycloak. SSO, SCIM provisioning, MFA and role mapping to internal applications.
Marketing & analytics
Klaviyo, Mailchimp, Brevo, ActiveCampaign, Segment, GA4. Event tracking, contact sync, transactional emails and consent-managed flows.
HR & payroll
AFAS, Nmbrs, Loket, BambooHR, Personio, Visma. Employee events, leave integration, salary import into accounting and SSO to the HR portal.
CMS & PIM
Directus, Strapi, Sanity, Contentful, Storyblok, Akeneo, Pimcore, inriver. Content and product sync to storefronts, mobile apps and marketplaces.
Custom and legacy systems
SOAP services, EDI (EDIFACT, X12), AS/2, SFTP feeds, on-premise databases, legacy SAP systems. With a modern API layer on top, we make them accessible to contemporary applications.
Our approach: integrations that last
Not all integrations are equally critical. An ad hoc CSV import for a one-off migration doesn't need an audit trail; a real-time order flow between webshop and ERP does. We scale our approach to the impact of the integration.
Discovery & data mapping
1-3 weken: we mappen velden, identificeren transformatieregels, valideren wat in beide systemen kan en mag, en beoordelen risico's. Output: integratie-blauwdruk met scope, fasering en effort.
Pattern selection
For each integration we choose the right pattern: real-time API, webhook-driven, batch sync, event bus or hybrid. Pragmatically, based on volume, latency requirements and operational complexity.
Built with first-class concerns
Centralised authentication, retry with backoff, idempotent endpoints, dead-letter queues for permanent failures, an audit log per request, and rate-limit-aware design. No afterthoughts.
Test and sandbox environments
Sandbox credentials for vendor APIs, mock servers for offline testing, and end-to-end smoke tests in CI. No "we test in production and hope it works".
Gradual rollout & monitoring
Feature-flag-driven rollout to 5%, 25% and 100% of flows. Dashboards for success rate, latency and error types. Alerts go to the right owner when anomalies occur.
Documentation and knowledge transfer
ADRs for architectural decisions, runbooks for operations, and handover sessions with your team. By the end of the project your team should be able to run the integration independently, with our remote support for whatever still requires it.
Integration patterns we use regularly
No one-size-fits-all. For each integration we choose the pattern that suits volume, latency, complexity and budget.
Direct API integrations (point-to-point)
Voor enkelvoudige koppelingen tussen twee systemen met overzichtelijk verkeer. Snel, simpel, weinig moving parts. Verstandig zolang u niet meer dan 3-4 systemen verbindt.
Middleware / iPaaS
For five or more systems, or where transformation and orchestration logic becomes complex: a dedicated middleware layer or an iPaaS platform (Mendix, Boomi, Workato, n8n). One place for flow design, monitoring and versioning.
Event-driven via message bus
Order, inventory and customer events on a bus (Kafka, RabbitMQ, Azure Service Bus). Consumers scale independently, retries and dead-letter handling are built in, and you get an audit trail along the way.
API gateway with service orchestrator
For complex enterprise scenarios with multiple customers and service levels: a gateway for routing, rate limiting and authentication, and an orchestrator for workflows across services.
Tech stack we typically use
Pragmatic choices with strong community support and long roadmaps. We avoid tools that will no longer be maintained in two years' time.
Middleware platforms
n8n for low-code workflows, Mendix where your team has already opted for low-code, and Boomi and Workato for enterprise-scale iPaaS.
Custom middleware
NestJS or FastAPI for custom services. Spring Boot or .NET 8 where they fit your stack. Always TypeScript or another statically typed language, to limit refactoring risk.
Events & messaging
Kafka, RabbitMQ, Azure Service Bus, AWS SQS+SNS. NATS for lighter setups. Schema registries (Avro, JSON Schema) for version discipline.
API gateway
Kong, AWS API Gateway, Azure API Management, Cloudflare API Shield. Rate limiting, authentication and API key management out of the box.
Observability
Datadog, Grafana+Prometheus+Loki, OpenTelemetry for tracing. Request-level logs so that post-mortems don't take hours.
Authentication & secrets
OAuth 2.0, OpenID Connect and mTLS wherever they are the standard. HashiCorp Vault, Azure Key Vault or AWS Secrets Manager for credentials, never in code.
What sets us apart on integration projects
Anyone can write an API call. The difference lies in choices that will still serve you well in three years' time, rather than forcing a rebuild.
Vendor-independent abstraction layers
There is always a dedicated abstraction layer between your business logic and the external API. If the supplier changes their API, or you switch platforms in two years, you only rebuild the adapter, not the applications that use the data.
Idempotent endpoints and transactional semantics
A duplicate message must never create duplicate orders. For every integration we think from the outset about idempotency keys, deduplication and transactional outbox patterns where needed.
Honest triage
Not every pain point deserves a new integration. Sometimes it is better to adjust a process, deliver a report or use a different system. We will tell you if we think an integration would not add value.
Maintenance built in from day one
Documentation, runbooks, ADRs, monitoring dashboards and SLA baselines are delivered alongside the integration. At the end of a project you do not have a black box, but a maintainable part of your IT landscape.
Frequently asked questions about building integrations
What is the difference between an API, an integration and middleware?
An API is the interface a system exposes. An integration is the working connection that synchronises data between two or more systems. Middleware is an intermediate layer where logic, routing and transformation come together, useful once you are connecting multiple systems or have complex transformations.
Which integrations do you build most often?
ERP integrations (Exact, AFAS, Microsoft Dynamics, SAP), e-commerce (Shopify, Magento, WooCommerce), CRM (Salesforce, HubSpot), payments (Mollie, Stripe, Adyen), shipping (Sendcloud, PostNL), document automation (PandaDoc, DocuSign), CMS (Directus, Sanity), HR (AFAS, Nmbrs) and custom EDI/SOAP for legacy partners.
What if the supplier does not have a modern API?
Then we work with what is available: SOAP, EDI, SFTP feeds or, in extreme cases, screen scraping. We shield the older protocol behind our own REST or GraphQL layer so your modern applications can communicate with it as normal.
How do you ensure the integration is robust?
Idempotency, retry with backoff, dead-letter queues, monitoring with alerts, sandbox testing and gradual rollout. We also record architectural decisions in ADRs and build runbooks for operations so your team knows what to do during incidents.
How long does a typical integration take?
Een eenvoudige point-to-point koppeling tussen twee bestaande API's: 2-4 weken. Een complexere flow met transformatie en monitoring: 6-12 weken. Een breder middleware-platform met meerdere koppelingen: 3-9 maanden in fases.
How much does an integration cost?
Eenvoudige koppelingen 5-20k. Middelgrote integraties met monitoring en transformatie 20-60k. Een middleware-platform met meerdere systemen kan 80-300k worden. Concrete inschatting na de discovery — niet op basis van een gesprek van 30 minuten.
Do you work together with our supplier?
As standard. We coordinate technical sessions, agree on API version changes and carry out joint testing where needed. We already have vendor relationships with the most common suppliers.
Do you maintain the integration after going live?
Yes, under an SLA agreement. Many clients choose to have Appfront support them remotely for resolving supplier API changes, monitoring anomalies and periodic maintenance, while day-to-day operations remain with their own team.
Ready to get your systems genuinely talking to each other?
We start with integration discovery: you get an honest picture of which integrations deserve priority, which patterns suit your scale, and what a realistic plan looks like. No sales pitch.