RESTful APIs & Microservices Development

From monolith to decoupled & microservices

Most web applications begin life as monoliths. As complexity grows, adding features stops being fast or cheap — and the usual fix is to split the application into smaller, independently deployable pieces. The first move is usually to decouple frontend from backend, with the backend exposing its functionality through an API.

From there, the backend itself gets split into self-contained microservices, each owning its own data model and business capability. The pay-off is faster iteration, better testability, lower risk on individual changes, and the freedom to migrate part of the system to a different technology without rewriting the whole.

APIs & Microservices: REST, GraphQL, gRPC

On the web, RESTful APIs over HTTP with JSON payloads remain the default for public and partner-facing interfaces. For lower-latency or strongly-typed internal contracts, we also deploy gRPC and GraphQL — each in the places where they earn their weight.

At Vantino, we regularly design and deploy custom APIs and microservice architectures in the cloud. We build to OpenAPI specs, generate clients automatically, run contract tests (Pact, Postman) to catch breaking changes before they ship, and instrument every service with OpenTelemetry for distributed tracing.

Securing APIs & microservice architectures

Securing the APIs we ship is part of the build, not a layer added afterwards. We have specific expertise to:

implement OAuth 2.1, OpenID Connect (OIDC), and JWT flows correctly
enable Single Sign-On (SSO) across distributed services
integrate third-party identity providers (Google, Microsoft, GitHub, Okta) or build with Keycloak, Auth0, Authelia
support mTLS for service-to-service auth and WebAuthn / passkeys for user-facing flows
apply rate-limiting, request signing, and audit logging at the API gateway

Scaling: gateways, containers, edge

A well-designed microservice architecture scales horizontally — services run as containers behind a load balancer or API gateway (Kong, Tyk, AWS API Gateway, Cloudflare, Apigee) and replicate on demand.

We deploy on AWS, Google Cloud, and Azure for managed environments, and on Hetzner, Scaleway, or Exoscale when cost or sovereignty matter. For container orchestration: Docker, Kubernetes, Helm. For infrastructure-as-code: Terraform and OpenTofu. For globally-distributed latency-sensitive workloads we run logic at the edge (Cloudflare Workers, Vercel, AWS Lambda@Edge).