API Backend Developer

RXinsider LTD.; Philadelphia (Philadelphia County); On-site; USD 120,000 - 160,000; Full time

Job summary

RXinsider LTD. in Philadelphia is seeking a Backend API and Integrations Software Engineer III to design, build, and operate distributed services and APIs at scale, with emphasis on Kong API Management, HL7 FHIR, and enterprise integrations using Java and JavaScript.

You will own the API lifecycle from design to testing, implement gateway policies and secure service-to-service authentication, and collaborate across teams to deliver resilient, observable systems in a production environment.

Qualifications

• 3+ years of professional backend software engineering.
• Proficient in Java; working proficiency in JavaScript/Node.js.
• RESTful API design, OpenAPI/Swagger, contract testing, backward compatibility.
• Hands-on Kong APIM experience with routes, plugins, auth, rate limiting.
• Distributed systems fundamentals: statelessness, service discovery, retries.
• Networking fundamentals: TCP/IP, TLS/mTLS, HTTP/2/HTTP/1.1.
• FHIR familiarity: HL7 FHIR resources and adapters.
• Testing: unit/integration/contract testing; CI/CD with YAML.
• Cloud/Docker/Kubernetes experience.

Responsibilities

• Design and build resilient microservices and integration components.
• Configure Kong Gateway routes, plugins, auth, rate limiting via YAML and CI/CD.
• Develop a FHIR data facade mapping internal data to FHIR resources.
• Own API lifecycle: design, testing, versioning, and SLO-driven operations.
• Implement secure coding practices and secure network policies.

Skills

Backend engineering

Distributed systems

API design

Security & compliance

OpenAPI/Swagger

Tools

Java

Node.js

Kong API Manager

YAML

OpenAPI

Job description

Backend API’s and Integrations Software Engineer III

About the role: We’re seeking a Software Engineer III with strong backend engineering skills to design, build, and operate distributed integration services and APIs at scale. You will focus on Kong API Management, backend API lifecycle (setup, testing, maintenance), HL7 FHIR, and enterprise integrations, primarily using Java and JavaScript. The ideal candidate has solid network fundamentals, can work comfortably with YAML (for declarative configs and pipelines), and thrives in pragmatic, production-oriented engineering—no frontend development in this space.

About the team, this team is building a generative-AI-powered clinical decision support tool designed specifically to help healthcare professionals quickly find trusted, evidence-based answers at the point of care. It combines a massive curated medical knowledge base with conversational AI so clinicians can ask questions in natural language and get concise, clinically relevant responses backed by real scientific evidence.

Responsibilities

Design & Build Distributed Services

• Implementing resilient, observable microservices and integration components (Java preferred; Node.js/JavaScript where appropriate).


• Applying patterns for scaling, fault tolerance, idempotency, and backpressure in distributed environments.

API Platform & Kong APIM

• Configuring and managing Kong Gateway (routes, services, plugins, rate limiting, auth, mTLS, logging) via declarative config (YAML) and CI/CD.


• Implementing gateway policies for security, traffic control, blue/green/canary releases, and zero-downtime migrations.

Integrations & Data Facades

• Building and maintaining a FHIR data facade that maps internal domain data to FHIR resources (read/search/transform), ensuring correctness and performance.


• Developing backend integrations with downstream systems (REST, gRPC, messaging/queues) and handle schema/contract evolution.

API Engineering

• Owning the API lifecycle: design (OpenAPI), implementation, automated testing (unit/integration/contract), versioning, and SLO-driven operations.


• Creating and maintaining OpenAI specs, mocks, and validation pipelines.

Security & Compliance

• Implementing OAuth2/OIDC flows, token introspection, and service-to-service auth. Apply secure coding practices and least-privilege network policies; partner with InfoSec on reviews.

Required Qualifications

• 3+ years of Professional Experience in backend software engineering.


• Languages: Proficient in Java; working proficiency in JavaScript/Node.js.


• API & Integrations: RESTful API design, OpenAPI/Swagger, contract testing, backward compatibility/versioning.


• API Gateway / Kong APIM: Hands-on experience configuring routes, plugins, auth, rate limiting, and declarative YAML configs; CI/CD integration.


• Distributed Systems: Understanding of microservices fundamentals: statelessness, service discovery, retries/circuit breakers, caching.


• Networking Fundamentals: TCP/IP, DNS, TLS/mTLS, HTTP/2/HTTP/1.1, proxies, load balancing, and common troubleshooting (cURL, traceroute, etc.).


• Data & FHIR Facade: Experience working with HL7 FHIR or adapters; familiarity with FHIR resource modeling and transformations (e.g., Patient, Observation, Encounter).


• Testing & Quality: Unit, integration, and contract testing; test automation and CI/CD pipelines (YAML-based workflows).


• Cloud & Ops: Experience deploying and operating services in a cloud or containerized environment (Docker/Kubernetes).