Top Principal Software Engineer Jobs in Chicago, IL

Lead development of core client systems and engine-level infrastructure in Unity/C#. Diagnose and fix cross-cutting performance issues, upgrade third-party SDKs, evolve build tooling, produce design docs, scope multi-week infrastructure initiatives, mentor engineers, and drive profiling, optimization, and architecture changes to enable future features.

Lead frontend architecture and implementation for a high-performance SPA and Node.js BFF. Solve algorithmic, concurrency, and memory challenges, optimize performance and builds, drive observability, security, and CI/CD, mentor engineers, and collaborate with product, UX, and SRE teams to deliver resilient, distributed real-time collaborative features.

Lead long-term technical strategy and execution across multiple teams, architecting and evolving foundational frontend/backend systems and platforms at massive scale. Drive AI/ML adoption, solve ambiguous, high-impact problems, remain hands-on in critical system design and implementation, and align senior leaders on roadmaps and engineering standards.

The Principal Software Engineer will lead platform initiatives, promote AI usage, ensure architecture stability, mentor engineers, and influence technical strategy across teams.

Lead reliability, performance, and operational excellence for large-scale ad-tech distributed systems. Design and operate monitoring, incident response, capacity planning, automation, and secure production infrastructure. Mentor engineers, influence architecture for production readiness, run on-call rotations, and drive continuous improvement of engineering operations and observability.

Lead design and build of scalable backend systems and data platforms; own architecture and production deployments; improve reliability, performance, and observability; mentor engineers and collaborate with Product, Data Science, SRE, and Security.

Design, evolve, and optimize Scala-based, low-latency trading services. Lead architecture for scalability and performance, tune JVM/Akka systems, enhance observability, ensure security and regulatory compliance, and mentor junior engineers while collaborating cross-functionally to support 24x7 high-volume trading.

Design, develop, test, and integrate embedded software and firmware (Linux/VxWorks) across the full SDLC using OOP C++, scripting, version control, and agile/DevSecOps practices to support complex defense systems and customer integration.

Develop and maintain embedded software and firmware for defense systems using C++ on Linux or VxWorks. Participate in full SDLC: requirements, design, coding, testing, integration. Work with model-based engineering, DevSecOps, version control, and Agile practices; interface with customers, suppliers, and engineering teams. Position may be filled at Software or Principal level and requires US citizenship and government clearance.

Design, develop, test, and integrate embedded software and firmware for defense systems. Apply object-oriented C++ development, scripting, and version-control practices across the full software lifecycle. Work in Agile/DevSecOps and model-based engineering environments, interface with stakeholders, and support on-target hardware integration and debugging.

Lead enterprise architecture and design of highly scalable, fault-tolerant distributed systems. Define standards for microservices, API governance, observability, CI/CD, reliability engineering, and drive cross-team modernization while mentoring senior engineers.

Senior technical leader owning end-to-end platform strategy, architecture, and delivery for Digital Enablement. Hands-on coding, driving modernization to cloud-native, API/microservices/event-driven designs, embedding AI-first practices, ensuring reliability, observability, and engineering excellence while mentoring teams and influencing cross-functional stakeholders.

Lead design and delivery of cloud-based solutions, collaborate with customers and product teams, produce extensible code, mentor engineers, own design documents and dependencies, act as a designated responsible individual (DRI) including on-call system monitoring, and improve reliability, performance, and observability at scale.

Lead architecture for high-volume distributed systems using Domain-Driven Design. Provide platform strategy, project-embedded consultation, CI/CD automation, and cloud-native architecture guidance to ensure reliability, scalability, security, and operational excellence.

Lead QA for a high-value billing platform: build agentic/AI-driven test tooling, validate streaming and batch billing logic, automate CI/CD testing, support revenue forecasting and cross-functional billing coverage.

Lead platform strategy, architecture, and hands-on development. Design, build, deploy, and operate high-performance, fault-tolerant integrations and platform enhancements. Drive security/compliance, mentor engineers, recruit senior talent, align technology with business goals, and communicate technical vision to stakeholders.

Design and implement scalable full-stack solutions for institutional platforms. Lead API and microservices design, cloud (AWS) deployments, CI/CD and DevSecOps, collaborate with product and QA, troubleshoot production, and mentor distributed teams.

Design, architect, and build enterprise Java microservices and APIs; lead technical delivery, mentor engineers, implement cloud-native and CI/CD practices, design database schemas and PL/SQL, and develop blockchain/digital-asset solutions including smart contract work and lifecycle integration in financial services.

Lead end-to-end design, development, and quality of cloud-based enterprise software solutions for caregivers. Define quality criteria, estimate costs, manage risks and engineering processes, integrate systems, and act as technical leader across large, complex projects.

Lead architecture and development of large-scale VM management and monitoring platforms for Azure. Provide technical leadership, design documentation, debugging, performance tuning, operational excellence, mentoring, on-call monitoring, and adoption of AI-assisted workflows to improve reliability, availability, security, and observability across Windows and Linux environments.

Drive architecture and technical vision for Elasticsearch core storage and query engine. Lead performance and storage-efficiency improvements, design indexing/serialization/data layouts, mentor engineers, coordinate cross-organizational initiatives, triage community issues, and write idiomatic modern Java for logs and metrics workloads.

Lead frontend technical direction for the Trellis design system: design and build a production component library, define accessibility and theming models, create tooling and migration pipelines (codemods, refactoring automation), leverage AI coding agents, mentor senior engineers, and partner with PM/UX to drive frontend architecture and adoption across product teams.

The Principal Software Engineer leads a team to develop full-stack real-time applications, integrates machine learning models, and influences software architecture in cloud environments while supporting healthcare analytics.

Lead architecture, modernization, and development of Group Insurance applications. Modernize mainframe monoliths into Java microservices and micro-frontends on cloud, mentor distributed Agile teams, collaborate with enterprise architecture, product owners and infrastructure, and enable test automation and integrations. Approximately 10% domestic travel.

Define frontend technical strategy and standards across the org, establish data layer and state management best practices, collaborate with AI Developer Experience on AI-assisted frontend tooling, embed with teams to write code (~50% time), drive platform-level operational excellence, influence executive strategy, and mentor engineers to raise frontend architecture and developer experience.