Top Principal Software Engineer Jobs in Los Angeles, CA

Design, build, deploy, and maintain resilient, scalable production systems for Toast’s retail customers. The role sets long-term technical architecture and strategy, communicates technical direction, mentors senior engineers, improves engineering productivity, diagnoses performance issues, and drives initiatives amid ambiguity. Engineers collaborate directly with retail customers, visit stores, understand operational workflows, and use AI tools to improve development velocity and quality.

Design and scale critical, highly-available services; set technical direction across teams; apply best practices for availability, scalability, cost, and operational excellence; leverage AI tools and high-velocity workflows; mentor engineers and solve ambiguous, company-wide technical problems.

Lead architecture and technical execution for Toast’s Payroll and Team Management products. Own authentication, authorization, and organizational hierarchy across a multi-tenant SaaS platform. Drive high-scale, full-stack initiatives, modern agentic development practices, integrations, technical strategy, quality standards, deployment practices, and cross-functional collaboration. Mentor engineers across teams and leverage AI tools and LLM integration to improve software development velocity and quality.

The Principal Software Engineer will design and implement systems for the advertiser experiences at Snap, lead technical vision, mentor engineers, and innovate on creator marketplace products.

Design and build next-generation ads formats, backend infrastructure, and scalable distributed systems. Lead technical direction, collaborate across teams to define product requirements, experiment, analyze and optimize ad performance, and ensure availability, scalability, operational excellence, and cost management. Mentor engineers and apply AI tools and high-velocity workflows to deliver production-ready systems.

Lead architecture, design, and delivery of PET product features; write production full‑stack code; champion testing, observability, CI/CD and operational readiness; mentor engineers and collaborate with product to shape technical roadmap.

The Principal Software Engineer will design automated ad serving systems, lead technical direction, collaborate with teams, and mentor engineers.

As a Senior Principal Engineer, you'll define and drive the technical strategy for customer experience platforms, lead architectural decisions, and mentor engineering teams to enhance customer and agent experiences.

Lead design, build, deployment, and operation of highly resilient, high-throughput configuration and publishing systems. Define long-term architecture and strategy, mentor senior engineers, diagnose and fix performance bottlenecks, and leverage AI tools to improve engineering productivity and platform capabilities.

Design and deliver core platform capabilities for FloQast Transform, building scalable, resilient distributed systems, AI agent infrastructure, and a visual workflow builder. Lead high-level architecture and engineering best practices, translate product needs into technical roadmaps with Product and Design, and mentor senior engineers to raise team performance and delivery.

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.

Own cross-team, platform-level engineering initiatives end-to-end: architecture, migrations, observability, on-call, and customer outcomes. Drive AI-native tooling and agentic AI adoption, mentor senior engineers, and set technical standards across teams.

As a Principal Flight Software Engineer, you will lead the architecture and development of flight software for space missions, ensuring safety and reliability while collaborating on technical decisions and standards.

Lead the technical vision and architecture of simulation software for spacecraft, focusing on multi-physics modeling and real-time execution, while driving engineering standards and mentoring teams.

Lead technical vision and execution for gameplay features in an unpublished game. Design and implement complex systems, prototypes, gameplay tools, and content pipelines spanning environments, physics, audio, and navigation. Collaborate with designers, artists, animators, producers, quality teams, and engineers; provide technical guidance on tooling and product direction; mentor engineers; and deliver systems across PC, console, and mobile platforms.

Design and scale Starlink’s Content Delivery Network, building distributed systems, traffic-shaping infrastructure, monitoring, alerting, and optimization algorithms. Lead architecture, design, and code reviews; develop prototypes and experiments for future capabilities; and improve hardware utilization, cost efficiency, reliability, and real-time operations across multiple CDNs.

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.

Develop and deliver Java software products throughout the design, implementation, build, test, and release lifecycle. Create JEE enterprise solutions in SOA environments using web technologies, XML, JMS, and related tools. Collaborate in integrated product teams with software developers, system engineers, hardware designers, and integration/test engineers. Work full-time onsite in San Diego or El Segundo, with travel up to 25%. The role requires a transferable Top Secret clearance and obtaining Special Program Access.

Develops and maintains C++ and Python modeling and simulation software; integrates components with system interfaces, middleware, and test harnesses. Leads verification, validation, troubleshooting, performance optimization, and CI/CD activities. Collaborates with systems engineers, testers, and stakeholders to translate requirements into scenarios, document technical work, and support demonstrations. This is a full-time, on-site role requiring an active Top Secret clearance, SAP access eligibility, and up to 10% travel.

Own the architecture and development of Valar Atomics’ software platform spanning reactor telemetry, streaming, simulation, enterprise systems, and full-stack tools. Build high-volume time-series ingestion and event-driven systems, support scientific computing platforms, integrate PLM, ERP, MES, and records systems, and establish deployment, observability, testing, and quality practices for a regulated environment. Set technical direction, lead reviews, mentor engineers, and collaborate with engineering, manufacturing, licensing, supply chain, and operations teams.

Lead design and implementation of Azure full‑stack, scalable skilling platform features. Drive CI/CD, reliability, automation, and AI/LLM-enabled capabilities. Mentor engineers, enforce engineering best practices, coordinate cross-team dependencies, and improve test automation and observability for enterprise-scale services.

Define technical direction for hyperscale Azure Storage components; architect, develop, test, and support highly scalable, secure, compliant, and highly available cloud services. Lead multiple engineering projects, improve reliability, scalability, performance, consistency, and observability, and apply AIOps for incident detection, root-cause analysis, and operational excellence.

Lead architecture and engineering for Azure core platform: define technology requirements, resolve cross-team issues, drive systemic reliability/performance improvements, mentor engineers, support on-call operations, and apply AI/ML to cloud operations.

Design and implement PostgreSQL internals, indexing, query engine extensions, and storage-layer features to support large-scale document workloads on Azure. Profile distributed systems, tune performance, collaborate with open-source communities, conduct design/code reviews, and drive cross-team alignment for mission-critical database features.

Principal Software Engineer responsible for expert-level coding, system architecture, technical strategy, code quality, SDLC improvement, and enterprise-scale modernization. Designs distributed systems and API integrations, governs architectural change, drives resiliency, security, observability, and performance standards, and influences stakeholders across multiple teams. Mentors engineers, leads technical initiatives without direct authority, manages technical risks and dependencies, and ensures compliance with regulatory, audit, and corporate engineering standards.