API Integrations
API Integration Agency in Stockholm - Platform Integration Built to Last
We design, implement and document integrations that hold up - whether you are building something new or untangling an existing system landscape.
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REST, GraphQL, and Webhooks
API design is one of the decisions that shapes your digital product the longest. Choose the wrong protocol or architecture early, and you pay for it every time a new integration needs to be added. Shapp designs APIs with a clear objective: easy to maintain, straightforward to extend, and reliable under load.
REST APIs remain the industry standard for most integration scenarios. We follow the OpenAPI specification, version consistently, and generate documentation automatically using tools such as Swagger and Postman. That gives your internal teams and external partners a clear contract to build against.
GraphQL is the right fit when you have complex data requirements and want to give frontend teams precise control over which fields are fetched per request. We design schemas, implement resolvers, and configure authentication and rate limiting - with performance in focus from day one.
Webhooks are the underappreciated component of many integrations. Implemented correctly, they replace polling with real-time events and reduce server load significantly. We build webhook endpoints with signature validation, idempotency handling, and retry logic so that no events are lost, even during transient failures on the receiving end.
All integrations are delivered with technical documentation and a thorough handover to your own teams. We are happy to tell you more about how we approach our other services such as streaming and AI development.
Payment Integrations
The payment flow is the most sensitive step in the customer journey. A drop-off at checkout is a lost sale that rarely comes back. Shapp has deep experience integrating leading payment services in ways that maximise conversion and minimise friction for the end user.
We work with:
- Stripe - subscriptions, one-time purchases, trial periods, Stripe Connect for marketplace models, and automated billing with webhook-driven status management.
- Klarna - buy now pay later, instalment plans, and built-in credit assessment for Nordic and European markets. We ensure the UI flow is optimised for mobile devices, where the majority of Klarna purchases happen.
- Adyen - enterprise payments supporting 200+ payment methods, tokenised card storage, and 3DS2 authentication for PSD2 compliance. The right choice if you sell globally and need a single integration surface across all markets.
Beyond the payment flow itself, we connect financial reporting to your accounting systems, handle refund logic, configure fraud rules, and implement tokenised access for subscription-based products. We have substantial experience with platform integration for streaming services where payment status controls content access in real time.
CRM and Data
Data stuck in silos creates blind spots for marketing, sales, and product teams. The value of your customer data is only realised when it moves without friction between the systems that actually use it.
Shapp builds data pipelines and integrations for:
- Salesforce - bidirectional synchronisation of leads, accounts, opportunities, and support cases. We integrate via the REST API and the Salesforce Streaming API for real-time events, and implement custom objects where your business processes require them.
- HubSpot - CRM integrations with marketing automation, lead scoring, and synchronisation of conversion events from your digital product. Ideal if you want to feed behavioural data directly into HubSpot's email flows and segmentation.
- Data pipelines and BI - we design ETL flows and event-based pipelines into data warehouses such as BigQuery, Redshift, and Snowflake. Dashboards in Looker Studio, Power BI, or Tableau connected directly to production data in real time.
A well-designed data architecture is not just a technical advantage - it is a competitive one. Marketing teams that see behavioural data in real time can act faster, and product teams with access to full conversion data make better prioritisation decisions.
Our Process
We follow an integration process that balances speed with long-term reliability. It typically looks like this:
- Discovery and mapping - we audit your existing systems, API documentation, and data flows, and identify dependencies and risks early.
- Architecture selection - based on discovery, we recommend protocol, authentication model (OAuth 2.0, API keys, JWT), and error-handling strategy.
- Proof of concept - we validate the integration against live endpoints before full implementation begins, eliminating late-stage surprises.
- Implementation and testing - we write integration tests, end-to-end tests, and load tests to confirm that the integration holds up under production traffic.
- Documentation and handover - every integration is delivered with technical documentation, runbooks, and, if needed, training sessions for your team.
- Ongoing support - we offer retainer agreements and post-launch support covering monitoring, updates, and new functionality. See our pricing page for details.
Frequently asked questions about API integrations
How long does a typical API integration take?
It depends on the complexity. A standard integration with Stripe or HubSpot can be completed in two to four weeks, including testing and documentation. More complex platform integrations with a custom data model and load testing typically take six to twelve weeks. We always structure the work in clear phases with defined deliverables at each stage.
Can you integrate with APIs that have poor or missing documentation?
Yes. We have experience working with legacy systems and underdocumented APIs. We conduct a technical analysis, test endpoints manually, and build an abstraction layer that protects you from future changes in the underlying API.
How do you handle security and GDPR in integrations?
Security is built in from the start. We implement OAuth 2.0 or API key management with appropriate permission levels, encrypt data in transit and at rest, and ensure that personal data is handled in accordance with GDPR. We document data flows so you always know where customer data resides.
What happens if a third-party service changes its API?
It happens, and we build with that in mind. We version integrations, set up monitoring with alerts on failure, and have processes for rapid updates when external APIs change. With a retainer agreement, we handle such updates at no additional cost.