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Connect and modernize systems

API Development & Integration. Your product gets its own interface that customers, partners and apps can build on.

We design and build a new API for your product or data – with OpenAPI, authentication and versioning

Proposal within 48 h How we work on it
  1. Workshop
  2. Setup
  3. Sprint
  4. Build & Support

Fixed price after scoping · proposal within 48 h

Reviewed: September 2026

API Development & Integration
API Development & Integration
API Development & Integration

API development is the design and build of a new programming interface (REST, GraphQL or RPC) for your own product or data set – with an OpenAPI specification, authentication and versioning.

Modern companies need flexible, secure, and performant APIs to connect different systems, services, and applications. We develop RESTful and GraphQL APIs that meet the highest standards in security, documentation, and performance – including CI/CD pipelines, full observability, and OWASP-compliant security. From API architecture through implementation to documentation, versioning, and typed client SDKs – we ensure your APIs work reliably, are easy to integrate, and are future-proof.

Who it's for

A fit if you want to open your own product or data to the outside: a SaaS application customers connect to via API, a mobile app that needs a backend, or data partners should be able to retrieve. It is about a new interface, not about connecting finished tools.

Key Features

  • Fast & performant
  • Documented
  • Version controlled
  • Secure
  • Observable & Traceable
  • CI/CD-Ready
  • Hono (Edge)
  • Fastify
  • GraphQL
  • tRPC
  • Connect RPC
  • OpenAPI 3.2
  • MCP
  • OTel

We select the optimal tech stack for your specific requirements

How we work on it

  1. Workshop
  2. Setup
  3. Sprint
  4. Build & Support
(01)

Sprint

Four weeks on one goal, with something that runs at the end.

4 weeks · fixed price after scoping
(02)

Build & Support

We build the project out and stay alongside you once it is live.

after scoping, ongoing · fixed price after scoping; support billed monthly

Included

(01)

API design with an OpenAPI specification before the first line of code

(02)

Authentication and permission model (e.g. OAuth 2.0, API keys)

(03)

Implementation with versioning and rate limiting

(04)

Automated tests and deployment to your environment

(05)

Developer documentation and handover to your team

Not included

(01)

Rebuilding the connected third-party systems themselves

(02)

Frontend or app development (separately after scoping)

(03)

Ongoing operations after the 30 days of bug fixing (optional via Build & Support)

How it runs

(01)

Scoping & API design

We clarify use cases, data model and consumers and capture the interface contract as an OpenAPI specification.

W1
(02)

Implementation & tests

Endpoints, authentication and error handling are built with automated tests; you see progress weekly in a staging environment.

W2-3
(03)

Deployment & handover

Go-live, documentation and handover to your team; followed by 30 days of bug fixing or further development in Build & Support.

W4
(01)

CRM System

Related Use Cases
(02)

Project Management

Related Use Cases
(03)

Invoicing

Related Use Cases
(04)

Crafts & Construction

Relevant Industries
(05)

Healthcare & Care

Relevant Industries
(06)

Gastronomy & Hospitality

Relevant Industries

In your city

API Development & Integration in 44 cities: city pages with local use cases and industries.

All locations

(01)

AI API development

Topic page
(02)

LLM integration into existing systems

Topic page
(03)

RAG development: AI grounded in your company knowledge

Topic page
(01)How does API versioning work?
We version via the URL path (e.g. /v1/, /v2/): a new major version only comes with breaking changes, everything else stays backward compatible. How far in advance breaking changes are announced and how long the old version keeps running in parallel is something we agree with you. You get migration guides, and deprecated endpoints are marked with Deprecation and Sunset headers (RFC 9745, RFC 8594).
(02)What support do you offer after launch?
We agree the scope of support, availability and response times in the contract – matched to your operations and to the availability commitments of the cloud services involved. From final delivery we fix bugs free of charge for 30 days; for ongoing operations there is the Build & Support format.
(03)Is there a sandbox environment for testing?
Yes, every API comes with a complete sandbox environment. This includes mock servers for contract testing, Postman collections, and interactive API documentation. Developers can integrate and test risk-free.
(04)How is API security ensured?
Our APIs follow OWASP API Security Top 10 guidelines. This includes: secure authentication (OAuth 2.0, JWT), input validation, rate limiting, audit logging, encrypted communication (TLS 1.3), and regular security audits.
(05)How does API development differ from tool integration and the enterprise API platform?
API development builds a new interface for your own product or data – with design, OpenAPI, authentication and versioning. If you only want to connect tools that already exist, tool integration with Make, n8n or webhooks is enough. If many internal systems and partners should work through one centrally governed interface with a gateway, SSO, rate limits and a developer portal, the enterprise API platform is the right service. We place your project in the first call.
View all frequently asked questions

Ready for your project?

Talk to us for 30 minutes with no obligation, or write to us directly.

Book a call Proposal within 48 h

Fixed price after scoping · proposal within 48 h