Senior Full Stack Engineer at Sphere | San Francisco

ABOUT SPHERESphere is revolutionizing trade compliance with cutting-edge AI technology. Our innovative system, TRAM, autonomously analyzes and interprets global trade laws, ensuring reliable compliance determinations across various jurisdictions. We manage the full compliance lifecycle—from calculation and registration to filing and remittance—with milliseco…

ABOUT SPHEREAt Sphere, we are redefining trade infrastructure by addressing one of its most complex challenges: compliance. Our innovative AI system, TRAM, simplifies the intricacies of global trade law, providing rapid and precise compliance determinations that outpace traditional methods.With significant backing from a16z and Y Combinator, we have achieved remarkable growth, serving diverse clients such as ElevenLabs and Replit. Join our small yet impactful team in San Francisco, where every member plays a pivotal role in our mission to streamline trade compliance.Startup Growth: Experience rapid expansion with 30%+ month-over-month growth and a $21M Series A funding.Dynamic Team Environment: Work closely with our Founder and CEO, where your contributions significantly influence our trajectory.Complex Challenges: Engage with evolving compliance landscapes, tackling input tax, e-invoicing, and more.

Join Sphere, where we leverage AI technology to redefine international trade law.At Sphere, we empower companies like Lovable, Eleven Labs, Replit, and Runway AI to seamlessly automate their sales tax, VAT, and GST compliance:Experience rapid growth with us (30%+ month-over-month revenue increase) as we collaborate with some of the fastest-growing tech companies globally.After two years of dedicated effort, we have integrated local compliance solutions into over 100 tax authorities worldwide, a feat unmatched by any other vendor.We are developing the first AI-native tax engine, forming the backbone of a comprehensive cross-border compliance platform.Our funding partners include industry leaders such as a16z, Y Combinator, 20vc, and Felicis Ventures.As we scale to accommodate millions of global transactions, building a robust infrastructure for transaction synchronization and real-time tax calculations is crucial.This role focuses on ensuring availability, resilience, and speed within mission-critical billing flows for leading companies.Why This Role is a Major Opportunity: Enormous Total Addressable Market: Every business requires compliance solutions. Favorable Market Trends: As businesses expand globally, the urgency for compliance solutions increases. AI-Driven Advantages: Our AI-native tax engine allows us to scale beyond traditional limitations. Multi-Product Expansion: Indirect tax is just our starting point; we are building a comprehensive solution for all revenue-based compliance needs.Your Responsibilities:In the initial weeks:Identify innovative solutions to enhance Sphere's infrastructure...

Join Sphere as a Lead AI EngineerSphere is pioneering the future of trade infrastructure by transforming compliance into a seamless, efficient process. We have developed an advanced AI system, TRAM, that interprets and navigates the complexities of global trade law, providing compliance solutions that surpass human capabilities in accuracy and speed.Located in the vibrant heart of San Francisco, our team thrives on innovation and collaboration. With backing from prominent investors like a16z and Y Combinator, we are rapidly growing and tackling the challenges of compliance in a dynamic global landscape.Your RoleAs the Lead AI Engineer, you will spearhead the development of TRAM, our proprietary AI reasoning model. This role is not merely about data lookup; it involves deep reasoning capabilities that have only become possible through the advancement of large language models (LLMs). You will design data pipelines that ingest complex legal information, create structured evidence, and build evaluation frameworks to ensure accuracy and performance. Your work will be critical as we scale to handle billions of transactions with minimal latency and zero downtime.What You'll AccomplishWithin weeks:Drive the development of features to enhance TRAM’s accuracy during testing.Collaborate on data and retrieval pipelines essential for our AI operations.Engage with our internal tax experts to refine TRAM’s reasoning capabilities.Within months:Take ownership of TRAM’s evaluation framework and workflows.Implement strategies to continually improve model performance.

ABOUT SPHEREAt Sphere, we are revolutionizing trade compliance by reducing transaction costs and expanding market access. Our innovative AI system, TRAM, processes global trade laws with unmatched precision and speed, enabling compliance determinations that surpass human capabilities. We manage the entire compliance lifecycle — from calculations to remittances — with lightning-fast efficiency and zero downtime.With backing from prestigious investors like a16z and Y Combinator, we have raised $21 million in Series A funding and are experiencing over 30% month-over-month growth. Our clientele includes industry leaders such as ElevenLabs, Replit, Deel, Runway, and Lovable.Join our small, yet impactful team in San Francisco, where each member owns significant responsibilities that would typically require large teams in bigger organizations. We are moving toward tackling the complexities of input tax, withholding, e-invoicing, and tariffs, anticipating billions of transactions in the near future.

Join sphere as a TRAM Lead, where you will spearhead innovative projects and drive operational excellence within our dynamic team. As a key player, you will collaborate with cross-functional groups to elevate our service delivery and enhance customer satisfaction. Your leadership will be pivotal in shaping our strategies and ensuring the successful execution of our initiatives.

Sphere develops AI-driven systems that help businesses navigate and comply with global trade laws. The core platform, TRAM, interprets regulations across more than 190 jurisdictions, enabling clients to stay compliant with speed and accuracy. Backed by a16z and Y Combinator, Sphere operates from its San Francisco headquarters. Role overview The AI Agent Infrastructure Lead guides the technical direction of Sphere’s AI agent infrastructure. This position sits within a small, collaborative team where each person’s contributions directly influence company growth. Sphere’s mission centers on automating compliance for global transactions, from calculation to remittance, to improve efficiency and market access. High reliability is essential, systems are engineered for zero downtime. What you will do Lead technical strategy and architecture for AI agent infrastructure Collaborate closely with a tight-knit team at the San Francisco HQ Ensure systems remain highly reliable and available Why Sphere? Tackle complex infrastructure challenges that affect real-world trade Make a direct impact on a product trusted in over 190 jurisdictions Work alongside a small, dedicated team shaping the company’s future Contribute to the evolution of compliance technology in a rapidly growing company

JOIN SPHERE AS A COMPLIANCE LEADAt Sphere, we are revolutionizing trade infrastructure by simplifying compliance, one of the most complex and essential components of global commerce. Just as containerization transformed goods transport and SWIFT enhanced financial transactions, our advanced AI system, TRAM, is set to redefine compliance. It seamlessly ingests and interprets intricate global trade regulations across 190+ jurisdictions, providing compliance determinations that surpass human expertise.We manage the entire compliance lifecycle—calculation, registration, filing, and remittance—delivering results with millisecond latency and zero downtime.Invested by a16z and Y Combinator. Our $21M Series A funding and 30%+ month-over-month growth reflect our success, with clients including ElevenLabs, Replit, Deel, Runway, and Lovable.Small, agile team with a global impact. Each team member is a domain owner, contributing significantly to our mission. Our San Francisco office operates five days a week.Growing complexity in compliance. As we expand into areas like input tax, withholding, e-invoicing, and tariffs, the challenge intensifies. We handle millions of transactions today, with billions on the horizon.ROLE OVERVIEWWe are on the lookout for a dedicated Compliance Lead to oversee the comprehensive indirect tax filing and compliance process across various jurisdictions. This pivotal role involves ensuring timely, precise, and scalable return preparation and review, while implementing processes that mitigate risk and enhance efficiency.As the operational backbone of our tax function, you will take charge of compliance, allowing the broader team to scale effectively.WHAT YOU'LL DOWithin your first days:Collaborate directly with our head of tax on:Managing the monthly and periodic tax filing cycle for thousands of returns.Overseeing timelines, deliverables, and team coordination.Ensuring that all filings are completed accurately and punctually.Within months:Designing and implementing scalable compliance processes.Collaborating with engineering to enhance automation.Streamlining manual efforts while boosting reliability.

Join a pioneering team of former Google engineers who have developed ground-breaking defensive technologies, such as Safe Browsing and reCAPTCHA. We are on a mission to confront an urgent challenge: combating the rising tide of adversarial AI attacks that threaten organizations globally.Operating in stealth mode, we are targeting a lucrative $5B+ market that is primed for innovation. Conventional detection methodologies are proving inadequate against the speed and sophistication of AI-driven assaults. Current adversaries are leveraging AI to engineer tailored, high-evasion attacks, leaving traditional systems vulnerable.Your Role:You will design a network of AI agents that are rapid, cost-effective, and precise, collaborating to identify and neutralize emerging threats. Your work will dive deep into real-time threat data, continuously evolving your agents in a fast-paced environment. These agents will function under an orchestration layer that fosters quick adaptation and learning.The Excitement of the ChallengeRapidly Evolving Models: The landscape changes daily; solutions that worked yesterday may be outdated today.Intelligent Adversaries: We are engaged in a real-time arms race against cunning, AI-enhanced attackers crafting sophisticated payloads.No Existing Playbook: We are forging new detection paradigms as swiftly as threats evolve. This high-stakes work places you in the heart of the action from day one.If you thrive on solving challenging problems with rapid feedback, this is your opportunity.Why We Are Positioned to SucceedExpansive Market: The market is vast at $5B and expanding quickly, while established players struggle to adapt.Proven Track Record: Our team has previously developed the foundational technology for Safe Browsing (serving over 5B users) and reCAPTCHA (protecting more than 5M websites) during our time at Google.Experienced Team: This is our third endeavor in creating a category-defining security enterprise, and we know how to scale our technology and our organization effectively.Deeply Integrated AI and Security: We embed AI from the outset rather than layering it on top.Top Talent: We hire only the highest achievers; many on our team were in the top 1% of engineers at Google. If you excelled in your previous role, you will fit right in.Agility: We prioritize speed and efficiency in everything we do.

Join Hilbert, a pioneering growth engine that leverages data science to provide B2C teams with predictive insights into user behavior, key revenue drivers, and strategies for sustainable growth. Designed for agility, Hilbert condenses lengthy decision-making processes into mere minutes.Trusted by Fortune 10 enterprises and beloved brands such as FreshDirect, Blank Street, and Levain Bakery, our platform is the backbone of their growth strategies. We are also collaborating with leading AI companies to co-create innovative solutions.We are in search of a Lead AI Engineer who is ready to take charge of the technical direction of Hilbert's AI infrastructure, engage in hands-on development of production-grade systems, and enhance our expanding engineering team with a founder's mindset of ownership and urgency.This position is not about managing from afar; you will be actively coding, making architectural decisions, establishing high standards for quality and speed, and cultivating our engineering culture as we grow. You will be the go-to person for navigating ambiguous challenges, high-stakes situations, and uncharted paths. If you possess a deep technical expertise coupled with strong leadership and communication skills, we would love to connect with you.THE ROLEYou will collaborate closely with the founding team and various departments, including product, data, and go-to-market teams to lead the design, development, and continuous improvement of the AI systems that power Hilbert. You will be deeply involved in coding daily while also defining how we approach development, prioritize tasks, and grow the engineering team. Our environment is characterized by high autonomy and ambiguity, which is inherent in building AI-driven products. Requirements may shift, methodologies can evolve, and the individual closest to the issue will often make the pivotal decisions. As the Lead, it is your responsibility to ensure the team is empowered to make those informed decisions effectively.Build: Hands-on, every dayDesign, build, and maintain AI-powered features and pipelines tailored for enterprise customers at scale.Architect and implement agent-based workflows utilizing frameworks such as LangChain or LangGraph.Take ownership of critical systems from experimentation to production deployment and monitoring.Develop and refine evaluation pipelines to assess, validate, and iterate on AI system performance.Make pragmatic engineering decisions in the face of uncertainty; ship, learn, and iterate.Lead: Set direction and elevate standardsDefine and own the technical roadmap for the AI stack in collaboration with the founding team.Make architectural and infrastructural decisions that drive our AI initiatives forward.

About Retell AIRetell AI is pioneering the future of customer service by leveraging first principles to transform the call center experience through advanced voice AI technology.In just 18 months since our inception, our innovative AI voice agents have been utilized by thousands of companies to efficiently manage sales, support, and logistics calls, significantly reducing the need for large teams of human agents. With the backing of esteemed investors such as Y Combinator and Alt Capital, we have achieved an impressive $36 million ARR, growing from $5 million at the beginning of 2025 with a dedicated team of 20 professionals.Our ambitious vision for 2026 is to develop a state-of-the-art CX platform powered entirely by AI. We aim to create intelligent AI 'workers' that will function as frontline agents, QA analysts, and managers, capable of autonomously executing, monitoring, and enhancing customer interactions.We are rapidly expanding and seeking passionate innovators eager to solve challenging technical problems, work swiftly, and make a tangible impact at one of the fastest-growing voice AI startups. Join us in shaping the future.Recognized as a top 50 AI app in a16z's list: https://tinyurl.com/5853dt2xRanked #4 on Brex's Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025Listed among the top-ranking startups at: https://leanaileaderboard.com/About the RoleAs the Support Engineering Lead at Retell, you will be responsible for overseeing the technical support operations of our sophisticated voice AI platform. This hands-on leadership position involves directly troubleshooting complex customer challenges, developing AI agents and automations, and leading an expanding team of support engineers.You will work at the intersection of engineering, customer relations, and product development, ensuring unparalleled reliability, swift issue resolution, and scalable support systems as Retell continues its growth trajectory.This position is perfect for individuals who thrive on resolving intricate technical issues under pressure, engaging with clients directly, and constructing systems and teams from the ground up.

About Retell AI Retell AI builds voice AI technology for call centers, helping thousands of companies handle sales, support, and logistics calls with AI voice agents. Since launching 18 months ago, the company has grown annual recurring revenue from $5M to $50M, backed by investors including Y Combinator and Alt Capital. Our Mission By 2026, Retell AI aims to deliver a customer experience platform powered entirely by AI. The vision goes beyond basic automation: intelligent agents will take on roles as frontline workers, quality assurance analysts, and managers, improving customer interactions while reducing the need for ongoing human involvement. Recognition Ranked among the top 50 AI applications by a16z (a16z List) #4 on Brex's Fast-Growing Software Vendors of 2025 (Brex Benchmark) High placement on the Leana AI Leaderboard Working at Retell AI The team is expanding quickly and welcomes those who want to solve tough problems and help shape the future of voice AI. Retell AI is based in the San Francisco Bay Area and continues to grow as one of the industry's fastest-moving startups.

Join Our Innovative Team at Simple AIAt Simple AI, we are transforming enterprise communications through cutting-edge voice AI agents. Our highly realistic agents empower leading companies such as DoorDash, xAI, and Omaha Steaks to efficiently manage a variety of phone operations, including customer support, order processing, and lead qualification.As we experience exponential growth and a surge in customer demand, we are seeking a few founding software engineers to help us navigate this exciting journey and develop systems for the future. Our passionate team operates from our vibrant San Francisco office five days a week, driven by a shared vision of leveraging AI to make a significant impact in the world.We are proud to be backed by esteemed investors and operators, including Y Combinator, Massive Tech Ventures, and industry leaders such as Michael Seibel (Twitch), Jared Friedman (Scribd), and more.

fractional-ai is hiring a Software Engineer to join the team onsite in San Francisco. This role centers on building and improving technology that advances artificial intelligence. Role overview As a Software Engineer, you will work closely with others to develop and support projects that drive the company’s AI initiatives forward. The work involves collaborating with colleagues and contributing technical solutions in a team setting. What you will do Develop software for AI-driven projects Collaborate with team members in the San Francisco office Contribute ideas and technical expertise to ongoing initiatives Requirements Interest in technology and artificial intelligence Ability to work onsite in San Francisco Strong motivation to learn and contribute to team projects

Role OverviewLocation: San Francisco, CA Work Model: In-officeAbout Effective AIAt Effective AI, we are pioneering the future of work, focusing on sophisticated AI solutions for complex knowledge tasks rather than simple, repetitive functions. Our goal is to develop advanced AI Teammates that excel in intricate workflows and collaborate seamlessly with human professionals. Our initial challenge is to revolutionize the trillion-dollar U.S. Property & Casualty insurance sector, an area rich in data and complexity, ideal for our innovative approach.We have successfully secured $10 million in seed funding from prominent investors including Lightspeed Ventures and Valor Equity Partners.Our passionate team operates out of San Francisco, where we value in-person collaboration to address these pressing challenges.Your ResponsibilitiesAs a Founding Software Engineer, you will be an integral member of our founding team, significantly influencing the design and development of our core product from inception. You will confront critical challenges in agentic AI, crafting Teammates capable of managing essential insurance functions such as underwriting and claims processing.Specifically, you will:Facilitate long-term task completion by creating the foundational architecture for AI agents to plan and execute multi-step processes reliably over prolonged interactions.Develop advanced reasoning functionalities, enabling agents to make informed decisions based on ambiguous or incomplete information, akin to human experts.Create intelligent, tool-utilizing agents capable of selecting and employing a variety of external tools—APIs, databases, web searches, and Excel-based pricing algorithms—to gather information and take decisive actions.Design adaptive and learning systems, equipping our AI Teammates to learn from feedback and adjust to evolving conditions such as regulatory changes or market dynamics.Your ProfileWe seek an innovative and driven builder excited to tackle substantial challenges.You possess a solid foundation in computer science and remarkable problem-solving capabilities, evidenced by impactful projects or previous experience.Your genuine enthusiasm for AI fuels your passion for tackling complex issues.

Saris AI develops advanced AI automation for the banking sector, with teams in San Francisco, Montreal, and Toronto. The company addresses large-scale automation challenges, focusing on long-context reasoning, integrating with legacy systems, and meeting strict compliance needs. Saris AI’s AI agents are already active in production, supporting real customer workflows as the business expands. Role overview The San Francisco engineering team is seeking an Engineering Manager. This leader will guide engineers through shifting priorities and frequent ambiguity. The position involves building and leading teams, managing projects from concept to launch, and ensuring the delivery of reliable software that powers AI-driven products. What you will do Build and lead engineering teams focused on automation and AI Oversee software projects from initial idea through production launch Adapt to changing requirements and priorities as the company grows Address the technical challenges unique to deploying software in AI systems Requirements Proven experience building and leading engineering teams History of delivering software projects from start to finish Comfort working in environments where priorities and requirements shift quickly Understanding of the complexities involved in AI-driven software deployment Location This role is based in San Francisco.

ABOUT SPHEREAt Sphere, we believe that transformative advancements in trade infrastructure drive market expansion and reduced transaction costs. Just as containerization revolutionized goods transport and SWIFT transformed money transfers, we are tackling one of the last frontiers: compliance. With over 190 sovereign jurisdictions constantly evolving and interacting, navigating trade rules is a complex challenge.Our cutting-edge AI system, TRAM, intelligently processes global trade law, expertly resolves jurisdictional conflicts, and delivers compliance determinations that outperform human experts. We manage the entire compliance lifecycle—calculation, registration, filing, and remittance—with unmatched speed and reliability.Backed by a16z and Y Combinator. With a $21M Series A funding round and over 30% month-over-month growth, our esteemed clientele includes ElevenLabs, Replit, Deel, Runway, and Lovable.A small, agile team with a global impact. Each team member possesses ownership over a domain that would represent an entire team at a larger company. We operate out of our San Francisco HQ, requiring in-office presence five days a week.The challenge is continuously evolving. As we expand into areas such as input tax, withholding, e-invoicing, and tariffs, the complexity multiplies. Today, we handle tens of millions of transactions, with billions on the horizon.THE ROLECustomer experience (CX) is pivotal at Sphere. Trust is paramount when it comes to managing payments and tax obligations for our clients. Every aspect of the user experience—from modals and buttons to exports—must be executed flawlessly. Would you trust a payment platform filled with bugs and inconsistencies?We are seeking a passionate founding product engineer to enhance our CX, elevate it to new heights, and contribute to the development of innovative features and products aligned with our roadmap.In this role, you will work closely with customers, collaborate with our design and engineering teams, and engage directly with our CEO and Founder to actualize Sphere’s vision of creating a unified global market.WHAT YOU'LL DOWithin your first few weeks:Engage with numerous customers to identify their core pain points and prioritize features that address their needs.Collaborate intensively with design teams to bring those features to fruition.Consistently execute and launch features from start to finish on a daily basis.Participate in customer support as needed to deepen your understanding of our users and their challenges.

About the RoleWe are on the lookout for a skilled Forward Deployed AI Engineer to join our dynamic team at Stack AI. This position is crucial for implementing enterprise-level AI solutions with an emphasis on Retrieval-Augmented Generation (RAG) pipelines and large language model (LLM) workflows. Your contributions will significantly enhance our offerings to Fortune 500 companies and enterprises across diverse sectors.Role Overview:In this role, you will seamlessly integrate large language models into enterprise systems, collaborating with strategic accounts to tailor solutions that meet their technical needs. Utilizing the Stack AI platform, you’ll engage with clients to co-create innovative solutions that address their evolving challenges.Key Responsibilities:Enhance and maintain solutions for strategic accounts using the Stack AI platform.Analyze and document requirements and relationships within target enterprise offices.Identify opportunities and provide insights to shape our go-to-market strategy.Directly contribute to the Stack AI codebase, transforming customer feedback into enhancements for the Python backend and React/Next.js TypeScript frontend.Project future opportunities and secure high-value contracts.Draft proposals, present to stakeholders, and lead engaging product demonstrations.Promote Stack AI at enterprise conferences and events.

About David AIDavid AI is pioneering the audio data research landscape, applying a rigorous R&D approach to dataset development akin to the methodologies used in AI labs for model creation. Our goal is to integrate AI seamlessly into real-world applications, with audio serving as the perfect entry point due to its inherent versatility and human connection. As the audio AI field progresses, the demand for high-quality training data becomes critical, and that's where David AI excels.Founded in 2024 by a team of experienced engineers and operators from Scale AI, David AI has quickly gained traction, serving prominent clients among FAANG companies and AI research labs. Recently, we secured a $50M Series B funding round from esteemed investors including Meritech, NVIDIA, Jack Altman (Alt Capital), Amplify Partners, and First Round Capital.Our team embodies intelligence, humility, ambition, and a close-knit ethos. We are on the lookout for exceptional talent in research, engineering, product, and operations to join us in advancing the frontiers of audio AI.About Our Engineering TeamAt David AI, our engineering team is responsible for constructing the pipelines, platforms, and models that convert raw audio into valuable data for top AI labs and enterprises. We pride ourselves on our collaborative environment, comprising product engineers, infrastructure specialists, and machine learning experts dedicated to leading the charge in audio data research.We operate at a fast pace, taking ownership of our projects from conception through to production. Our team develops real-time processing pipelines capable of managing terabytes of audio data daily while deploying innovative generative audio models.About This RoleAs a Product Engineer at David AI, you will design and implement state-of-the-art tools that enable our users to leverage audio data effectively for training their AI models. You will collaborate closely with researchers to continuously refine our data collection methodologies.Your ResponsibilitiesDeliver full-stack features that will be utilized by thousands of users on a daily basis.Develop scalable systems that create essential data processing pipelines, extracting actionable insights from terabytes of audio data each day.Construct, deploy, and assess LLM and DSP-based solutions to enhance our clients' comprehension of intricate features within our datasets.Rapidly iterate on research hypotheses by collaborating with researchers and the operations team to deploy enhancements efficiently.

About Simple AIAt Simple AI, we are pioneering cutting-edge voice AI solutions tailored for enterprises. Our lifelike voice agents empower renowned companies such as DoorDash, xAI, and Omaha Steaks in managing diverse phone operations ranging from customer support to order intake and lead qualification. As we experience rapid revenue growth, we seek a couple of founding software engineers to help us meet current customer demands while developing innovative systems for the future. Our team is passionate about harnessing AI to transform the world, and we operate from our San Francisco office five days a week.Simple AI is proudly supported by top-tier investors and industry leaders, including Y Combinator, Massive Tech Ventures, and prominent figures like Michael Seibel (co-founder of Twitch), Jared Friedman (Scribd), Alexandr Wang (Scale AI), Matt Van Horn (June Oven and Lyft), Suhail Doshi (Mixpanel), JJ Fliegelman (WayUp), and Scott Wu (Cognition).Meet the FoundersThe founders, Catheryn Li and Zach Kamran, previously led software teams at Y Combinator, where they launched numerous products for YC founders, including the co-founder matching site. Cat brings experience from Instagram and Facebook and holds degrees in mathematics and computer science from MIT. Zach studied computer science and statistics at the University of Chicago and led software initiatives at PEAK6.What We ProvideCompetitive salary with significant equity opportunitiesEmployee-friendly equity termsOffice located in San FranciscoComprehensive health, dental, and vision insuranceComplimentary lunch and dinner at the officeFree Uber rides home after 8:30 PMRegular team events and offsite activitiesYour Qualifications4+ years of relevant software engineering experience.Exceptional problem-solving skills and a passion for tackling technical challenges.A customer-centric mindset coupled with strong communication skills and a keen interest in product design and prioritization.Self-motivated with the ability to work independently.A genuine enthusiasm for continual learning and keeping abreast of the latest advancements in AI.