Kodelinesoftware engineering
ENDE
API Development

We build backend and API architecture for systems where business logic, data integrity, and stable contracts matter more than framework speed. Clearly separated, tested, and documented for internal continuation.

Build

When this service makes commercial sense

This service is relevant when your frontend or mobile product is blocked by backend instability, unclear data ownership, slow integrations, or business logic that only one developer understands. Backend domain logic is often the actual business value: calculations, approvals, data validation, multi-tenancy, integrations, or reporting. Typical triggers are fragile integrations, business rules hidden in controllers or scripts, unclear API contracts, database changes with side effects, or an internal team that needs a maintainable backend foundation.

Project output

What you own after the project

You receive a traceable backend foundation that separates business logic, API contracts, and data access cleanly enough for your team to continue.

Documented backend architecture with system and module boundaries
API contracts and OpenAPI documentation where useful
Tested core logic for critical use cases
Data model, migration plan, or integration boundaries for existing systems
.NET, Node.js, or Python depending on system context
PostgreSQL, SQL Server, Firestore, or managed databases
REST, GraphQL, or event-based interfaces
AuthN/AuthZ, OpenAPI, logging, and automated tests
Cost drivers

Pricing follows backend complexity, not endpoint count

Effort depends on domain rules, integrations, data model, security requirements, and migration risk. A CRUD API is a different scope from a backend that owns central business logic and system integration.

Complexity of business rules and validation

Number and risk of external integrations

Data model, migrations, performance, and deletion concepts

Authentication, roles, security, and traceability

Anonymized project evidence

Evidence from comparable backend projects

The evidence stays intentionally technical and anonymized so protected business processes and system details are not published.

API layer in front of legacy data

Existing data structures were made usable for new frontends through clear adapters, DTOs, and read/write boundaries.

Evidence: OpenAPI, adapters, migration paths

Backend for regulated workflows

Domain rules, approvals, and roles were moved from UI or script logic into tested backend use cases.

Evidence: use cases, RBAC, audit logging

Reporting and data consolidation

Several data sources were prepared for reporting through stable interfaces and a traceable data model.

Evidence: data model, exports, error paths
Decision knowledge

Related decision pages

Cost, delivery model, and technical risk should be clear before commitment. These pages expand the most relevant decisions for this service.

API Development

Specific delivery depth

We build backend and API architecture for systems where business logic, data integrity, and stable contracts matter more than framework speed. Clearly separated, tested, and documented for internal continuation.

Domain

Business logic as a stable core

Use cases, validation, and domain rules are pulled out of controllers, scripts, or UI layers and structured for testing.

  • Clean Architecture or modular service boundaries
  • Explicit use cases and error paths
  • Tests for critical domain rules
API Contracts

Interfaces teams can depend on

APIs are versionable, documented, and built with clear data contracts so frontends, mobile apps, and third-party systems can integrate reliably.

  • REST, GraphQL, or event-based APIs
  • OpenAPI and typed DTO boundaries
  • AuthN/AuthZ, rate limits, and error contracts
Data

Data access without hidden coupling

Data models and repository boundaries are designed so reporting, migrations, performance, and deletion concepts do not become expensive afterthoughts.

  • PostgreSQL, SQL Server, Firestore, or managed databases
  • Migration, indexing, and transaction strategy
  • Tenant, audit, and deletion concepts where needed
Integration

Legacy systems and external APIs under control

Existing databases, ERP/CRM systems, or external services are connected through explicit adapter and integration boundaries.

  • Anti-corruption layer for legacy schemas
  • Read models for reporting and UI
  • Migration paths with fallback strategy
Start your project

Tell us about your business logic.

We respond within one working day. The first call qualifies scope, constraints, budget corridor, risk, and fit. Architecture decisions are handled in a paid discovery or audit phase; fixed pricing follows only after reliable scope clarification.