Haystack
← Back to Jobs
Technology
SS

Senior Backend/ Integration Developer

S3 Staffing USAUnited States🇺🇸United StatesPosted Oct 2, 2026

Quick Overview

Seniority
Mid Senior
Work mode
Hybrid
Location
United States
Posted
Yesterday
SOAPSpringSpring BootAPI GatewayAzureC#ASP.NETGitHTTPHTTPSJavaRESTVault

Job Description

Senior Backend / Integration Developer

Enterprise Integration & API Development

Position Overview
We are looking for a Senior Backend / Integration Developer to design and implement backend integration
services connecting enterprise and warehouse systems. This is a hands-on senior engineering role requiring
strong experience with backend APIs, enterprise system integration, SOAP/WSDL services, data transformation
and mapping, error handling, observability, and integration testing.
The developer will take technical ownership of the application/backend workstream and collaborate closely with
cloud/platform engineers, QA, enterprise application teams, and external system owners.

Key Responsibilities
 Design and implement backend integration services and APIs.
 Define API contracts, request/response schemas, validation rules, and standardized error responses.
 Integrate with existing enterprise SOAP/WSDL web services and build maintainable SOAP clients from WSDL
definitions.
 Implement bidirectional data mapping and transformation between external systems and enterprise backend
services.
 Implement schema, mandatory-field, datatype, format, and allowed-value validation.
 Maintain a clean separation between external API contracts and underlying enterprise-system-specific data
structures.
 Implement synchronous request/response integration patterns.
 Implement consistent technical and business error handling, including SOAP faults, timeouts, validation
failures, and backend business rejections.
 Implement correlation IDs, structured application logging, and end-to-end request traceability.
 Externalize endpoints, timeouts, environment settings, and other runtime configuration.
 Develop unit and integration tests and support QA with mocks, sample payloads, and test scenarios.
 Support end-to-end integration testing across multiple environments and troubleshoot complex integration
issues.
 Collaborate with cloud/platform engineers on API gateway behavior, authentication, secrets management,
deployment pipelines, monitoring, and runtime requirements.
 Participate in architecture decisions around application runtime, API standards, integration patterns,
persistence, and future asynchronous messaging.
 Produce maintainable technical documentation, interface specifications, mapping documents, and handover
materials.

Required Technical Skills
 7+ years of backend/software engineering experience, with significant hands-on experience building
enterprise integrations.
 Strong expertise in at least one modern enterprise backend stack, preferably C#/.NET/ASP.NET Core or
Java/Spring Boot.
 Strong REST API design and implementation experience.
 Strong understanding of API contracts and schema-driven development.
 Hands-on experience with SOAP web services, WSDL, XML, and XML Schema (XSD).

Senior Backend / Integration Developer — Job Description

 Experience consuming and integrating legacy or enterprise SOAP services from modern backend
applications.
 Strong experience with JSON/XML transformation and complex field mapping.
 Experience implementing validation frameworks and standardized error models.
 Strong understanding of synchronous request/response integration patterns.
 Experience with OpenAPI or an equivalent machine-readable API specification.
 Strong knowledge of HTTP/HTTPS, authentication, headers, status codes, timeouts, and API error handling.
 Experience implementing correlation IDs, structured logging, distributed request tracing, and application
observability.
 Experience creating unit, integration, mock-based, and end-to-end tests.
 Experience with Git-based development workflows and CI/CD pipelines.
 Experience externalizing environment-specific configuration and securely consuming secrets/credentials.
 Strong debugging and troubleshooting skills across distributed systems.

Strongly Preferred Skills
 Experience integrating with SAP ECC, particularly SAP WM or similar SAP modules.
 Experience consuming SAP SOAP/Enterprise Services.
 Experience with warehouse systems such as WMS/WES, manufacturing systems, logistics platforms, or
industrial automation.
 Experience with API gateways such as Azure API Management.
 Experience developing applications deployed to Microsoft Azure.
 Familiarity with Microsoft Entra ID, Key Vault, centralized logging/monitoring, and cloud deployment pipelines.
 Experience designing vendor-neutral integration layers or middleware.
 Experience working with canonical data models and system-to-system mapping.
 Experience with idempotency, duplicate detection, correlation, transaction state, and reliable integration
patterns.

Similar jobs