Senior Software Engineer - AI & Simulation

Why Join UsAt Brex, we are revolutionizing corporate spending with our AI-driven platform. We empower businesses to manage their expenses confidently through integrated corporate cards, banking services, and global payment solutions, complemented by intuitive software for travel and expense management. From startups to established enterprises like DoorDash, Flexport, and Compass, thousands of companies rely on Brex to control spending proactively, reduce costs, and enhance efficiency on a global scale.Joining Brex means pushing your limits, questioning the status quo, and collaborating with some of the industry’s brightest minds. We are dedicated to fostering a diverse team and an inclusive culture, believing that your potential should only be limited by your dreams. We empower you with the tools, resources, and support needed to advance your career.AI at BrexOur AI Engineering team is redefining finance management by embedding intelligent, autonomous systems into the Brex platform. We develop AI agents that not only provide insights but also take action to optimize spending, manage workflows, and make real-time decisions for our customers. By integrating proprietary financial data with our product and platform infrastructure, we simplify complex financial operations into seamless, automated experiences, setting a new standard for modern finance.What You’ll DoAs a Senior Software Engineer, you will be responsible for Brex’s simulation and validation platform for AI-driven products. Your primary goal is to ensure that every AI interface at Brex is rigorously tested under realistic conditions, enabling teams to deploy with confidence.You will design a system that leverages synthetic data and scenario generation to create a recursive self-improvement loop. Product teams will depend on this platform to detect regressions proactively, validate new features safely, and continuously refine prompts and agent behaviors. This platform will operate within isolated, ephemeral environments closely resembling production.This is not a research position; it involves actively engaging with real products, creatively breaking them to foster organizational improvement.Where You’ll WorkThis position is based in our San Francisco office. We offer a hybrid work environment that blends the energy of in-office collaboration with the flexibility of remote work. We require team members to be in the office three days a week—Monday, Wednesday, and Thursday—while also allowing up to four weeks of fully remote work each year!

Why You Should Consider Joining DoppelAt Doppel, we are dedicated to combating one of the most pressing challenges posed by AI: the rise of mass-manufactured social engineering. With an alarming increase in scams, deepfakes, and various social engineering tactics infiltrating every digital platform—be it websites, social media, advertisements, or encrypted messaging applications—our mission is both straightforward and ambitious: to enhance internet safety by outsmarting the most rapidly evolving digital threats.Supported by leading investors and trusted by some of the world’s most prestigious brands, Doppel is on an exhilarating growth trajectory. If you are passionate about tackling real-world issues with innovative technology, we would be thrilled to connect with you.Our VisionWe are developing an AI-driven social engineering defense platform.This entails creating scalable systems that surveil billions of domains, social media accounts, applications, dark web forums, and more, utilizing AI agents to detect and mitigate digital threats.Your RoleWe are seeking a skilled full-stack engineer to contribute to the development of our innovative Simulation product. The Simulation team operates like a startup within a startup, within Doppel (a Series C company backed by Bessemer and a16z) and has already surpassed six figures in revenue shortly after launch, with a trajectory aiming for 1M ARR in Q4.Our goal is to empower businesses to proactively defend against the forthcoming wave of social-engineering attacks. We are crafting AI-driven phishing simulations that employ advanced language models and voice synthesis to replicate authentic threats—ranging from highly personalized emails to realistic “manager calls” that assess and train enterprise security teams.Joining our team means collaborating with leaders who have backgrounds at Meta and Y Combinator and are already engaging with Fortune 100 clients. This is a unique opportunity to experience the rapid growth and creativity of a startup, coupled with the stability and backing of an established company. It's the ideal environment to innovate quickly, implement meaningful change, and help shape an emerging market.Having just launched, we are witnessing fast-growing market traction and are eager for individuals who are excited to take initiative and fulfill our customers' pressing needs. For instance:Develop a “Cursor for phishing simulation” workflow that enables users to create simulations using natural language.Create voice deepfakes that utilize AI to impersonate employees during calls.

Waymo is at the forefront of autonomous driving technology, dedicated to becoming the most trusted driver globally. Originating from the Google Self-Driving Car Project in 2009, our primary goal has been to develop the Waymo Driver—The World’s Most Experienced Driver™. Our innovations aim to enhance mobility access while saving countless lives lost to traffic accidents. The Waymo Driver powers our fully autonomous ride-hail services and is adaptable across various vehicle platforms and product applications. Having completed over ten million rider-only trips, our technology has autonomously navigated over 100 million miles on public roads and executed tens of billions of miles in simulations across more than 15 U.S. states.Your Role:Lead the technical strategy for the Simulator’s issue response lifecycle, encompassing automated detection, root cause analysis, and the deployment of both temporary and permanent software solutions to prevent future regressions.Direct complex, cross-functional projects to enhance automated issue detection by integrating new data sources and signals, thus reducing the time from an in-field event to mitigation deployment.Work closely with Data Science, Systems Engineering, and operations teams to improve technical processes and tools, accelerating the deployment and validation of solutions for identified issues.Mentor mid-level and junior engineers on sophisticated technical challenges, best practices in system architecture, and high-quality software development, serving as a technical force multiplier.

Join formic as an Embodied AI / Simulation Engineer, where you'll have the opportunity to work on cutting-edge technologies that shape the future of AI and robotics. In this role, you will be responsible for designing, developing, and implementing simulation environments that enhance the capabilities of our embodied AI systems. Your expertise will drive innovations and optimize performance in real-world applications.

About Retell AIAt Retell AI, we are pioneering the future of call centers through innovative voice AI technology. Our cutting-edge solutions are transforming how companies engage with customers.In just 18 months since our inception, we've empowered thousands of businesses with our AI voice agents that efficiently manage sales, support, and logistics calls, significantly reducing the need for large teams of human agents. Supported by industry-leading investors including Y Combinator and Alt Capital, we've grown our annual recurring revenue from $5M to an impressive $36M while expanding our team from 5 to 20 talented individuals since 2025.Our ambitious vision for 2026 is to develop a state-of-the-art customer experience platform where entire contact centers are driven by AI. Unlike basic automation requiring constant human oversight, we’re engineering intelligent AI “workers” capable of serving as frontline agents, quality assurance analysts, and managerial roles, all while optimizing customer interactions continuously.We are rapidly expanding and seeking driven builders who thrive on solving complex technical challenges, act decisively, and wish to make a tangible impact in one of the fastest-growing voice AI startups.Join us in shaping the future!Recognized as a top 50 AI application in the a16z list: https://tinyurl.com/5853dt2xRanked #4 in Brex's Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025Featured among the top startups on: https://leanaileaderboard.com/

Responsibilities:Develop Our Product. Take ownership of software features that enhance our AI platform, empowering private market investors to analyze deals swiftly and accurately. This role requires you to actively engage in coding and delivering essential platform components from the ground up.Ensure Quality and Excellence. Establish and maintain coding standards, architectural guidelines, and review procedures; mentor fellow engineers. Co-cultivate a culture centered on practical, reliable, and test-driven development that swiftly meets business requirements.Scale for Growth. Assist in monitoring and scaling the architecture of our platform and its infrastructure.Collaborate Across Functions. Engage closely with product, security, and go-to-market teams to translate our strategic roadmap into actionable features and deliverables.

Astranis is at the forefront of satellite technology, specializing in the construction of advanced satellites designed for high geostationary orbits. Our innovative solutions extend humanity's reach into the solar system, delivering dedicated and secure network services to a diverse range of esteemed clients, including large corporations, sovereign nations, and the United States military. With five operational satellites and numerous upcoming launches, we are committed to fulfilling over $1 billion in commercial contracts.We pride ourselves on being the go-to partner for satellite communications, particularly for clients with rigorous demands regarding uptime, data security, network visibility, and customization. Backed by over $750 million in funding from prominent investors such as Andreessen Horowitz, Blackrock, and Fidelity, our team of 450 engineers and entrepreneurs is dedicated to advancing satellite technology. All operations, from design to assembly, are conducted in our state-of-the-art 153,000 sq. ft. headquarters located in Northern California.Position OverviewAs a Simulation Software Engineer within our Guidance, Navigation, and Control (GNC) team, you will play a pivotal role in designing, developing, and testing high-fidelity spacecraft simulations that validate the software controlling our satellites in orbit.In this position, you will enhance our core simulation infrastructure and work collaboratively with cross-functional engineering teams to model new systems and introduce exciting features into the simulator.

The Trade Desk is a leading global technology company dedicated to fostering a better, more open internet for everyone through principled, intelligent advertising. With the capability to handle over 1 trillion queries daily, our platform operates at an unparalleled scale. We pride ourselves on our award-winning culture, built on the foundations of trust, ownership, empathy, and collaboration. We appreciate the unique experiences and perspectives that every individual brings to The Trade Desk, and we are committed to creating inclusive spaces where everyone can express their authentic selves at work. If you are passionate about solving complex problems at scale and are eager to join a dynamic, globally-connected team where your contributions will significantly impact the media ecosystem, we invite you to explore why Fortune magazine consistently ranks The Trade Desk among the top small to medium-sized workplaces worldwide. As a Senior Software Engineer, you will have end-to-end ownership, allowing you to engage in various facets of designing, building, and delivering data-centric products for our stakeholders. At The Trade Desk, we focus on constructing the back-end infrastructure of our platform with an unwavering commitment to quality at scale. Whether developing components for our client-facing applications, crafting internal custom solutions for our teams, or building model pipelines for bidding optimizations, we ensure that the infrastructure, development processes, and tools empower us to execute efficiently. Our systems operate continuously, serving global traffic, and we collaborate in a highly cooperative environment while leveraging a diverse array of technologies. Our back-end developers tackle algorithmic, optimization, and scalability challenges across all our initiatives.

Join Waymo as a Staff Software Engineer specializing in Simulation Capacity Optimization. In this pivotal role, you will leverage your expertise in software engineering and simulation technology to enhance our autonomous vehicle systems. Your contributions will be vital in optimizing the performance and efficiency of our simulations, ensuring that our vehicles are equipped to navigate the complexities of real-world environments.

fractional-ai is looking for a Senior or Staff Software Engineer to join the San Francisco office. This position centers on building advanced AI solutions with a team that values both technical depth and collaboration. Role overview This role focuses on designing and developing AI-driven systems. The work involves solving technical challenges and contributing to projects that push the boundaries of what AI can achieve. Collaboration with other engineers and stakeholders is a key part of daily responsibilities. Who will thrive Experienced engineers with a strong background in software development Those who enjoy working on complex technical problems Individuals who value teamwork and open communication Location This position is based in the San Francisco office.

About Our TeamJoin our innovative Robotics team at OpenAI, where we are dedicated to pioneering general-purpose robotics and advancing towards AGI-level intelligence in dynamic, real-world environments. By working across the entire model stack, we seamlessly integrate state-of-the-art hardware and software to explore a wide variety of robotic form factors. Our mission is to harmoniously combine advanced AI capabilities with the constraints of physical systems, ultimately enhancing the lives of individuals worldwide.About the RoleWe are on the lookout for a passionate Simulation Realism Engineer to lead our initiative in achieving quantitative realism in simulation for robotics research and product development. You will be responsible for devising strategies, tools, and operational practices that bridge the sim-to-real gaps across physics, sensors, and rendering. Collaborating cross-functionally with research, software, hardware, and operations teams, you will identify key realism gaps, establish measurable realism metrics, and deliver impactful engineering solutions — from fine-tuning engine parameters and setting asset standards to integrating third-party engines and managing simulations at scale. This hands-on engineering role combines scientific precision (measurement & validation) with practical systems work (tooling, cloud ops, and CI/HIL pipelines).This position is based in San Francisco, CA, with a requirement of 4 days in the office per week. Relocation assistance is available for new hires.Your Responsibilities:Establish and operationalize realism metrics & protocols. Design experiments and automated tests to identify specific areas of non-realism, quantify gaps, and monitor regressions over time.Optimize engine parameters (contacts, friction, mass/density, solver settings) and object models to ensure simulated dynamics align with real-world measurements.Assess, integrate, and where necessary, extend third-party physics, rendering, and sensor simulation engines (e.g., Isaac, PhysX, MuJoCo). Lead vendor proof of concepts and benchmark features to inform roadmaps.Develop standards and guidelines for authoring and validating asset physical/visual properties; implement semi- or fully-automated pipelines to tune and optimize assets for target engines.Resolve technical challenges related to running engines in the cloud (OS, drivers, GPU), parallelize simulations (batch multiple runs per engine instance), and fortify real-world-facing pipelines to ensure reliable simulation at scale.Lead validation campaigns (teleoperation, HI...) to verify simulation accuracy and performance.

Join Our Innovative Robotics TeamAt OpenAI, our Robotics team is dedicated to pioneering general-purpose robotics and striving towards artificial general intelligence (AGI) within dynamic, real-world environments. By integrating advanced hardware and software, we explore a diverse array of robotic configurations, aiming to harmoniously combine high-level AI capabilities with the physical constraints of real-world systems to enhance everyday lives.Your Role as a Simulation Environments EngineerWe are seeking a talented Simulation Environments Engineer to develop the tools and infrastructure that facilitate the creation of comprehensive, realistic virtual environments for robotics research and evaluation. This position emphasizes building systems that empower researchers and engineers to define, visualize, generate, and validate task environments efficiently and at scale. You will design processes for importing and validating third-party content, develop procedural and randomized scenario generators, and produce user-friendly tools to streamline environment creation, making it swift, repeatable, and testable. This role sits at the convergence of game-engine expertise, asset engineering, and extensive simulation infrastructure.Location and Work ScheduleThis position is based in San Francisco, CA, requiring in-person collaboration three days a week.Key ResponsibilitiesDevelop interactive and programmatic tools for researchers to describe, preview, and validate scenes and tasks, enabling quick and consistent scenario authoring.Establish content pipelines to curate, convert, optimize, and quality-check visual and collision assets from both external collections and internal resources, ensuring consistent behavior across engines and tasks.Create robust importers and adapters to integrate environments and setups from platforms such as Isaac, Unity, Unreal, and Omniverse into our simulation pipelines, maintaining fidelity and performance.Develop frameworks for procedural generation and controlled randomization (covering visual, physical, and kinematic aspects) to provide models with systematic, measurable variations in conditions.Define and uphold quality standards for environments (including visual fidelity, collision accuracy, and physical realism) and implement validation tools to ensure environments meet established realism and coverage objectives.Link environment tools to CI/CD processes, presubmit checks, large-scale simulation farms, and model evaluation pipelines to facilitate automatic testing and large-scale execution of environments.

Join the Revolution at Retell AIRetell AI is pioneering the future of call centers through innovative voice AI, driven by first principles thinking.In just 18 months since our inception, we have empowered thousands of businesses with our AI voice agents, transforming how sales, support, and logistics calls are managed—previously requiring extensive human teams. Supported by prestigious investors such as Y Combinator and Alt Capital, we've rapidly scaled from $5M ARR to an impressive $36M ARR with a compact yet dynamic team of 20.Our ambition for 2026 is to create a revolutionary customer experience platform, where entire contact centers are powered by AI. Moving beyond basic automation, we aim to develop intelligent AI “workers” that serve as frontline agents, QA analysts, and managers, continuously enhancing customer interactions without the need for constant human oversight.As we expand, we are seeking passionate engineers who are eager to solve challenging technical problems, act swiftly, and make a significant impact in one of the fastest-growing voice AI startups. Let’s shape the future together.

Role overview retell-ai seeks a Senior Software Engineer in the San Francisco Bay Area to focus on Go-To-Market (GTM) projects. This engineer will help shape how new products are created and introduced to customers, directly influencing the company’s approach to launching and scaling offerings. What you will do Collaborate with teams across the organization to translate business needs into software that advances GTM objectives. Develop and improve products to ensure they fit seamlessly into the market. Uphold high standards for code quality and system performance as products grow and change. Collaboration This position works closely with product, business, and engineering partners to deliver solutions that address both technical and market demands.

Supported by key investors from Silicon Valley, Peregrine Technologies empowers public safety organizations, state and local governments, federal agencies, and private-sector institutions to address societal challenges with remarkable speed and precision. Our AI-driven platform transforms disconnected data into actionable insights—instantly delivering vital information that enables quicker, more informed decisions, resulting in improved outcomes across various touchpoints. Currently, Peregrine serves hundreds of clients in over 30 states and two countries, impacting more than 125 million people. We are poised for further growth as we expand into enterprise solutions and international markets.TeamAt Peregrine, our engineering team prioritizes empathy, believing it enhances our solutions. Observing how users interact with our product is essential as we navigate towards effective answers. Engineers will have the chance to collaborate onsite with our team, gaining insights into the diverse use cases we address.We cherish both ownership and teamwork—taking full responsibility for significant features while closely collaborating with fellow engineers to bring them to fruition. Humility and empathy are fundamental to developing optimal solutions, as we work directly with our deployment team and users to refine our offerings. Tenacity and creativity are vital in realizing our vision.RoleAs a pivotal member of our new AI team, you’ll play a key role in delivering unique value to our customers. This team is tasked with designing powerful, user-friendly experiences powered by generative AI. You will explore innovative methods for users to engage with our platform—whether through natural language commands or by enabling AI agents to manage complex tasks on their behalf. Your contributions will shape secure, impactful AI-driven features that assist clients in solving real-world issues more efficiently.Your responsibilities will encompass a variety of complex challenges, from scaling our platform to process terabytes of data from multiple sources to efficiently querying and alerting users in real-time, as well as optimizing search algorithms for quick results.Our tech stack is continuously evolving but is rooted in a backend framework of Python, Django, Celery, Airflow, and Kafka; a frontend constructed with React, Redux, and Mapbox; data storage solutions including PostgreSQL and Elasticsearch; machine learning models hosted in Bedrock and SageMaker; along with AWS, Pulumi, Terraform, and Kubernetes as our infrastructure.

Join Our Innovative Team at Retell AIRetell AI is at the forefront of revolutionizing the call center industry through advanced voice AI technology. In just 18 months since our inception, we have empowered thousands of businesses to optimize their sales, support, and logistics calls, which previously relied on large teams of human agents. Supported by prominent investors including Y Combinator and Alt Capital, we've achieved remarkable growth, scaling from $5 million to $36 million in annual recurring revenue (ARR) while expanding our talented team to 20 members.Our ambitious vision for 2026 is to develop a state-of-the-art customer experience platform, transforming entire contact centers with AI. Unlike traditional automation that requires ongoing human oversight, we are building intelligent AI "workers" capable of functioning as frontline agents, quality assurance analysts, and managers, constantly enhancing customer interactions.If you are a passionate innovator eager to solve complex technical challenges and make a tangible impact at one of the fastest-growing voice AI startups, we invite you to join us in shaping the future.Ranked among the top 50 AI applications by a16z: a16z List4th on Brex's Fast-Growing Software Vendors of 2025: Brex BenchmarkFeatured as a leading startup on: Leanaileaderboard

About tvScientific tvScientific is a pioneering CTV advertising platform designed specifically for performance marketers. We utilize extensive data and advanced science to automate and optimize TV advertising, ensuring impactful business outcomes. Our comprehensive solution integrates media buying, optimization, measurement, and attribution into a single, efficient platform. Developed by industry experts with extensive backgrounds in programmatic advertising, digital media, and ad verification, our platform stands as a reliable CTV performance tool for advertisers striving to expand their business. We are on the lookout for a talented Software Engineer to enhance our simulation and AI capabilities. You'll be responsible for designing and implementing systems that accurately model the CTV advertising ecosystem, including auction dynamics, bidding strategies, campaign results, and counterfactual scenarios. Moreover, you will innovate AI-driven tools that expedite the development, testing, and deployment of machine learning systems.

The Bot CompanyAt The Bot Company, we are on a mission to create an innovative robot for every household.Located in the heart of San Francisco, our dedicated team consists of talented engineers, designers, and operators with backgrounds from industry leaders like Tesla, Cruise, OpenAI, Google, and Pixar. Our collective experience includes delivering products to hundreds of millions of users, and we understand what it takes to craft extraordinary products and experiences.Our lean team structure fosters rapid decision-making and minimizes bureaucracy, allowing every individual to take ownership and responsibility. We embrace a culture of rapid iteration and swift execution, encouraging collaboration across various domains.Ideal Candidate TraitsWe seek candidates who exhibit exceptional sharpness and the ability to thrive in fast-paced, high-stakes environments. Throughout the hiring process, candidates should demonstrate:Exceptional mental acuity: Quick thinkers who can learn rapidly and navigate unfamiliar challenges.Engineering curiosity: A natural inclination to explore how systems operate, even beyond one's area of expertise.High-performance mindset: Ability to adapt swiftly, manage ambiguity, and excel in demanding situations.Role Overview: Simulation EngineerAs a Simulation Engineer, you will be responsible for developing and enhancing the simulation systems that drive our robotics development workflow. This includes implementing new simulation features, adjusting framework internals, and leveraging tools such as Isaac or MuJoCo to accurately replicate complex real-world behaviors.RequirementsProficient coding skills in Python and/or C++.Significant experience with Isaac or MuJoCo, including making substantial framework-level modifications and developing new functionalities.A strong academic or open-source background: high-quality datasets, public code contributions, a robust GitHub presence, and publications as a primary author.Key ResponsibilitiesDevelop new simulation features while extending the core physics and engine internals.Design high-fidelity simulations of robotic systems and their environments.Work collaboratively with cross-functional teams in robotics, perception, and platform domains to ensure simulation precision and scalability.Drive rapid execution and iteration on simulation improvements.

Join Us at Retell AIRetell AI is revolutionizing the call center industry by leveraging innovative voice AI technology based on first principles.In just 18 months since our inception, we have attracted thousands of companies that rely on Retell's AI voice agents to efficiently manage sales, support, and logistics calls, previously handled by large teams of human agents. Supported by renowned investors such as Y Combinator and Alt Capital, we have rapidly grown from $5M to $36M in Annual Recurring Revenue (ARR) with a dedicated team of 20.Looking ahead to 2026, our ambition is to establish a state-of-the-art customer experience platform entirely powered by AI. We aim to create intelligent AI “workers” capable of serving as frontline agents, quality assurance analysts, and managers, continuously optimizing customer interactions without the need for constant human oversight.We are on an exciting growth trajectory and are seeking driven individuals who are eager to solve complex technical challenges, accelerate progress, and make a significant impact at one of the fastest-growing voice AI startups.Let’s innovate the future together!Ranked as a top 50 AI app by a16z: https://tinyurl.com/5853dt2x#4 on Brex's Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025One of the top startups on: https://leanaileaderboard.com/