Senior/Principal Software Engineer

About Endurance

Endurance is building the world's first modular subsea geothermal power plants, converting vast thermal resources under the ocean into gigawatts of baseload power. Backed by Founders Fund, Felicis, First Round Capital, and Point72 Ventures, our founding team includes veterans from SpaceX, Helion, Blue Origin, and Apple. We have completed multiple deep-ocean deployments to subsea volcanoes and are launching a long-term demonstration project this fall. By leveraging modular design, manufacturing scale, efficient drilling, and latent cooling on the seafloor, we are pioneering a new category of energy that outperforms traditional sources on environmental impact, deployment speed, and cost.

What you'll be doing

As a Senior/Principal Software Engineer at Endurance, you will build the software stack, controls, UIs, and simulation infrastructure that allows our engineering team to rapidly build and validate every component and every subsystem that goes into a subsea geothermal power plant.

As we scale from our first hundred-kilowatt subsea demonstration to gigawatt deployments, the size and complexity of our test and production infrastructure will rise exponentially, rivaling the complexity of the power plants themselves. We believe an internal software team building the right stack from scratch is one of the highest-leverage moves we can make as we scale. Every improvement you make increases the speed at which mechanical, electrical, firmware, and controls engineers can design, test, iterate, and deploy hardware. Your job is to build the software ecosystem that enables that acceleration.

This role can span the entire software and hardware stack. You will work directly with electrical, mechanical, and test engineers to understand what they are building, identify how it should be tested, and rapidly create the infrastructure needed to answer critical engineering questions.

One day you will be writing bare-metal and Linux firmware interfacing with custom PCBs, large-scale industrial equipment, and next-gen Endurance power plants. The next you will be closely embedding with engineers to build data acquisition and visualization systems that allow engineers to understand and control plants in real time, and the first generation of Endurance’s unified testing platform. Beyond that you will be building a high-performance simulation stack to simulate our power plants and developing hardware-in-the-loop environments to test real operating conditions and failure modes.

As we scale, you will own the software stack to automate large-scale production lines for Endurance’s power plants, with the goal of a lights-out fully-automated factory.

The ideal candidate is an exceptional software engineer who enjoys working up and down the stack, from firmware to web UIs. You should be equally comfortable designing foundational software architecture, writing software for non-technical users, and debugging software with hardware in the loop. You be a part of Endurance’s software team and support firmware/full stack/controls projects across the company.

You will be the first software engineer focused on test and automation infrastructure at the company. You will work directly with the founding team and engineering leadership across Endurance, and as the function grows, you will have significant influence on the company’s software architecture, engineering standards, and future hires.

Key Responsibilities

Design and build the software ecosystem that powers testing across Endurance, from component qualification through full integrated system validation.

Architect and implement hardware-in-the-loop (HITL) and simulation environments that allow firmware and controls software to be tested under realistic operating conditions and failure scenarios.

Develop software for automated test execution, operator interfaces, data acquisition, visualization, storage, and analysis.

Design and integrate the electrical and controls infrastructure behind new test systems, including Endurance-designed PCBs, DAQs, PLCs, VFDs, sensors, instrumentation, and industrial communication networks.

Partner closely with firmware, electrical, mechanical, controls, and systems engineers to rapidly develop new testing capabilities.

Build scrappy one-off test systems when speed matters, then evolve successful concepts into scalable engineering infrastructure.

Write production-quality software while establishing the architecture and engineering patterns that future test systems will build upon.

Own the technical foundation of Endurance’s testing ecosystem as it grows from individual laboratory experiments to full power plant validation.

Collaborate with other members of the software team to support software projects across the company.

Help shape the test infrastructure organization as it grows, including interviewing and onboarding future engineers.

Required Qualifications

5+ years of software engineering experience.

Strong software engineering skills in Python, Rust, C++, C, or similar languages.

Demonstrated ability to ship production software end-to-end, from architecture through deployment and operation.

Track record building software for hardware systems, including automated testing, hardware-in-the-loop (HITL), industrial controls, robotics, aerospace, automotive, or other complex electromechanical products.

Technical fluency strong enough to hold credibility with mechanical, electrical, firmware, and systems engineers.

Ability to work onsite in Seattle and travel to deployment sites as required.

Preferred Qualifications

Familiarity with Rust and Nix.

Experience building hardware-in-the-loop (HITL) or software-in-the-loop (SITL) environments.

Experience developing simulation or emulation software for embedded or controls applications.

Experience with industrial automation platforms including PLCs, DAQs, VFDs, National Instruments, Beckhoff, Siemens, or similar systems.

Familiarity with industrial communication protocols such as EtherCAT, CAN, Modbus, or OPC UA.

Experience designing data acquisition and telemetry systems for hardware development.

Background in aerospace, robotics, automotive, energy, defense, or other fast-paced hardware industries.

Comfort working hands-on in the lab, including wiring sensors, debugging electrical systems, integrating instrumentation, and bringing up new test hardware.

Experience building internal engineering infrastructure that enables other engineers to move faster.

Compensation, Benefits, & Perks

As a pre-revenue startup, Endurance Energy offers competitive base salaries and generous equity packages for full-time employees. Final base salary will be determined by an array of factors including internal equity, job-related knowledge, skills, and work experience.

A key aspect of our compensation philosophy is that value creation should be aligned with rewards. Right now this means equity is a significant portion of every full-time employee's compensation. As the company matures, there will be continued evolution and changes to the total rewards and total compensation package. What will always be true is that if we win, we win together. Equity is granted to every full-time employee as a meaningful piece of ownership. We believe the people building the company should share directly in the value they create.

In addition to a competitive base salary and equity, employees will receive all of our other great benefits and perks, including:

Benefits : Health, Dental, and Vision insurance coverage

Time Away: Flexible PTO including 12 paid company holidays

Global Fieldwork : Travel to fascinating deployment sites along oceanic ridges in locations like the Pacific Northwest, Hawaii, Iceland, Japan, New Zealand, and the Azores

Hands-on Experience : Participate in sea trials and deployment operations in partnership with leading oceanographic institutions

Cutting-edge Deve