I design and implement reliable backend APIs and third-party integrations for web applications, SaaS products, and operational software.

What you receive • One backend module with up to 5 agreed REST endpoints, or one third-party integration • Data modeling and persistence changes required by the agreed workflow • Authentication or permission checks where applicable • Input validation and consistent error responses • Retry, idempotency, or webhook handling where the integration requires it • API documentation and setup notes • Testing against an agreed example checklist • Source-code delivery, one revision, and seven days of defect support

This service is suitable for payment, email, storage, CRM, analytics, AI-provider, and internal-system integrations, as well as new API modules for an existing application.

You provide the current stack, API documentation, sandbox access through a secure method, sample requests or data, and expected outcomes. Major data migrations, several providers, compliance certification, production infrastructure, and undocumented legacy-system recovery are quoted separately.

Third-party subscriptions and usage charges are not included.