Senior .NET Backend / API Integration Engineer

ESOL IT SERVICES INC.; Quezon City; On-site; PHP 1,200,000 - 2,100,000; Full time

Job summary

ESOL IT SERVICES INC. is seeking an experienced Senior .NET Backend / API Integration Engineer to join a health tech program focused on conversational AI solutions. You will lead backend services, API integrations, and orchestration across AI-powered platforms and enterprise systems.

Responsibilities include designing secure RESTful APIs, mentoring developers, and collaborating with architects, product owners, QA, and DevOps to drive CI and code quality.

Qualifications

• 8+ years of software development experience with strong .NET backend expertise.
• Proficient in C#, ASP.NET Core, Web API, and Entity Framework.
• Experience with RESTful APIs, API integration, and microservices.
• Experience designing backend orchestration for multiple services.
• Knowledge of API security (OAuth 2.0, JWT) and authentication.
• Experience with real-time integrations (webhooks, WebSockets).
• Proven leadership or mentoring experience.
• Familiar with Agile/Scrum and AI-assisted development tools.

Responsibilities

• Design, develop, and maintain backend applications and services.
• Build and manage API integration and orchestration layers.
• Develop, secure, and maintain RESTful APIs for integrations.
• Integrate third-party AI, voice, contact center, and enterprise platforms.
• Implement API authentication, authorization, and security standards.
• Provide technical leadership, conduct code reviews, mentor developers.
• Collaborate with architects, product owners, QA, and DevOps.
• Drive code quality, unit testing, and CI practices.
• Troubleshoot complex technical issues and optimize backend performance.

Skills

NET backend development

C#

ASP.NET Core

Web API

Entity Framework

RESTful API development

API integration

Microservices

OAuth 2.0 / JWT

Security best practices

Webhooks / WebSockets

Leadership / mentoring

Agile/Scrum

AI-assisted development tools

Azure OpenAI / Semantic Kernel

Azure Service Bus / Kafka

DevOps collaboration

Troubleshooting performance

Education

Bachelor's degree or equivalent

Tools

Azure OpenAI

Semantic Kernel

Azure Service Bus

Kafka

Job description

We are looking for an experienced Senior .NET Backend / API Integration Engineer to join a healthcare technology program focused on conversational AI solutions.

The successful candidate will lead the development of backend services, API integrations, and orchestration systems that connect multiple AI-powered platforms, third-party services, and enterprise applications.

This role requires strong technical expertise in .NET development, API architecture, microservices, and backend integration, along with experience providing technical guidance and driving development initiatives.

Key Responsibilities

• Design, develop, and maintain backend applications and services using C#, ASP.NET Core, and Entity Framework.

• Build and manage API integration and orchestration layers connecting multiple platforms and services.

• Develop, secure, and maintain RESTful APIs for internal and external integrations.

• Integrate third-party AI, voice, contact center, and enterprise platforms.

• Implement API authentication, authorization, and security standards.

• Provide technical leadership, conduct code reviews, and mentor developers.

• Collaborate with architects, product owners, QA, and DevOps teams.

• Drive code quality, unit testing, and continuous integration practices.

• Troubleshoot complex technical issues and optimize backend performance.

Qualifications

• Bachelor's degree or equivalent college graduate qualification.

• Minimum of 8 years of software development experience, with strong expertise in .NET backend development.

• Proficiency in C#, ASP.NET Core, Web API, and Entity Framework.

• Strong experience in RESTful API development, API integration, and microservices architecture.

• Experience designing backend orchestration or routing layers involving multiple services.

• Knowledge of API security, OAuth 2.0, JWT, authentication, and authorization.

• Experience with webhooks, WebSockets, or real-time integrations.

• Previous experience leading or mentoring development teams.

• Familiarity with Agile/Scrum methodologies and AI-assisted development tools.

Preferred Qualifications

• Experience integrating contact center, IVR, or voice platforms.

• Exposure to AI agents, LLM APIs, Azure OpenAI, or Semantic Kernel.

• Familiarity with Azure Service Bus, Kafka, or other event-driven integration technologies.