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# Senior Software Engineer in Test

- **Company:** Mainspring Energy
- **Location:** Menlo Park, CA, United States
- **Experience:** Expert
- **Salary:** $135,000.0 - $159,000.0
- **Contract:** Permanent contract
- **Skills:** Testing (Software), Artificial Intelligence, Automation of Tests, C++ (Programming Language), Cloud Computing, Continuous Integration, Python (Programming Language), Real-Time Operating Systems, Software Engineering, System Testing, Test Case, Computer Network Operations, AI Coding Agents, Information Technology, SDET
- **Published:** October 27, 2026
- **Apply:** https://www.careerbuilder.com/job-details/senior-software-engineer-in-test-menlo-park-ca--f39df727-bcc9-4ffe-9d9b-466aadb29dea

## About the Role

Software Engineering, Software Testing, Fortune 500 Customers, Network Operations Center, Electricity, Alternative Energy, Diving, Automation Systems, Internet of Things, Realtime Operating System, * Experience & Education: Bachelor's degree in Computer Science or a related field with 6+ years of professional experience, or a Master's degree with 5+ years in an SDET or Software Engineering role

 * Engineering Mindset: A driven, self-directed contributor who views test infrastructure as a first-class product; you thrive on architecting scalable, automated systems that increase developer velocity
 * Strategic Test Design: Proven track record of leading complex automation projects from design to implementation, with the foundational ability to perform deep-dive manual exploratory testing and technical test case design
 * Technical Versatility: Strong hands-on experience developing in Python and C++, with the flexibility to navigate and contribute to diverse codebases as the project requires
 * AI Workflow Ownership: Demonstrated proficiency in leveraging AI coding assistants as a force multiplier for productivity, combined with the professional judgment to challenge and expand upon AI-generated solutions to ensure system integrity and long-term maintainability

$135,000 - $159,000 a year

This position is onsite at our Menlo Park HQ. The salary will be adjusted to reflect local market conditions based on employee location as well as the experience of the employee. Along with base salary, Mainspring offers pre-IPO company equity through Restricted Stock Units (RSUs) + benefits.

## Description

Do you enjoy diving into building new automation systems and formulating new testing approaches in areas like cloud computing, networking, IoT with real time operating systems, controls, simulations (MIL, SIL, PIL), and algorithms? We combine this technology with our company vision of building a new category of power that is affordable, reliable, and targeting a net-zero carbon grid. This cornucopia of science and technology will be your daily career at Mainspring.

This is an opportunity for you to join a world-class engineering team: to build and run automated testing systems to ensure the quality of the product. This is an exciting opportunity to become part of a rapidly growing engineering team.

In this role. you will have significant influence over the quality of the product, engage with developers to understand new features and technologies, and create innovative automated testing solutions within tight requirements to solve complex scenarios with multiple components., * Architect Automation: Design and scale robust test frameworks and CI/CD integrations

 * System Validation: Create workflows to validate complex hardware/software integrations and resolve system-level bottlenecks
 * Root Cause Analysis: Lead failure analysis and risk mitigation to ensure test stability and environment reliability
 * Strategic Coverage: Drive risk-based testing strategies to ensure comprehensive coverage of all critical-path functionalities