Machine Learning Engineer / Scientist at Until | Bay Area

Join Retell AI as a Senior Machine Learning EngineerRetell AI is at the forefront of revolutionizing the call center industry using groundbreaking voice AI technology. Within just 18 months of our inception, we have empowered thousands of businesses with our AI voice agents capable of managing sales, support, and logistics calls that traditionally required extensive human teams.Supported by renowned investors, including Y Combinator and Alt Capital, our journey has seen us scale from $5M to an impressive $36M ARR with a dedicated team of 20. Our ambition for 2026 is to develop a state-of-the-art customer experience platform, transforming entire contact centers with AI. We are building intelligent AI “workers” that will serve as frontline agents, quality assurance analysts, and managers—constantly executing, monitoring, and enhancing customer interactions.We are rapidly expanding and seeking passionate innovators eager to solve complex technical challenges and make a tangible impact in one of the fastest-growing voice AI startups. Together, let's shape the future of customer interactions.

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.

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.

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

Join Retell AIAt Retell AI, we leverage first principles to revolutionize the call center experience through innovative voice AI technology.In just 18 months since our launch, our AI voice agents have been adopted by thousands of companies to manage sales, support, and logistics calls, significantly reducing the need for large teams of human agents. Supported by Y Combinator, Alt Capital, and other notable investors, we've achieved impressive growth, scaling from $5M to $36M ARR with a dedicated team of 20.Looking ahead to 2026, we aim to create a comprehensive AI-powered Customer Experience (CX) platform that transforms entire contact centers. Instead of simple automation requiring ongoing human oversight, we are developing intelligent AI "workers" that serve as frontline agents, QA analysts, and managers — perpetually executing, monitoring, and enhancing customer interactions.We're experiencing rapid growth and are on the lookout for passionate innovators eager to tackle complex technical challenges, accelerate progress, and make a significant impact at one of the leading voice AI startups.Let’s build the future together.Ranked in the top 50 AI applications by a16z: https://tinyurl.com/5853dt2x#4 on Brex's Fast-Growing Software Vendors list for 2025: https://www.brex.com/journal/brex-benchmark-december-2025One of the top startups on: https://leanaileaderboard.com/

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/

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/

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 Team as a Machine Learning EngineerSaris-AI is a pioneering applied AI startup, based in San Francisco and Montreal, focused on revolutionizing the banking sector. Our mission is to address a colossal $100 billion/year challenge that is rapidly expanding, innovating the limits of what can be achieved with advanced multi-turn AI systems.We aim to automate complex workflows that necessitate long-context reasoning, orchestration of tools across legacy systems, and rigorous compliance processes—solving problems that currently lack definitive solutions.Our team has successfully deployed AI agents that manage real customer workflows effectively in production. As we expand our customer base and accelerate our growth, we are in search of highly skilled technical builders who aspire to make a significant impact in the early stages of our journey.As a foundational Machine Learning Engineer, you will own our entire ML stack and bring custom agents to life.

About VSCO At VSCO, we empower photographers with an innovative platform that provides essential tools, a vibrant community, and the visibility needed for creative and professional growth. We cultivate an authentic creative environment that welcomes photographers of all skill levels, offering a space that inspires opportunity, collaboration, and connection. Our mission is to support photographers in their journeys, enabling them to thrive and connect with fellow creatives and businesses through our comprehensive suite of tools, available on both mobile and desktop. We seek individuals who are passionate and proactive in advancing our mission. Our team members have the opportunity to make a significant impact, and we believe that collaborative efforts yield stronger results. Our core values are essential to our team culture and guide our hiring process. Learn more about what you can expect when joining VSCO on our Careers Page. About The Role As a Senior Machine Learning Engineer, you will harness the power of AI and machine learning to create innovative, reliable user-facing product features. You will leverage your extensive technical background and hands-on experience in deploying machine learning models to deliver impactful solutions based on real-world feedback. Your focus on measurable outcomes and customer satisfaction drives your work, blending innovation with practical implementation. You will be highly skilled in Python and adept across the data and machine learning stack, enabling you to develop and launch models efficiently while ensuring scalability and maintainability. Whether working with traditional algorithms or cutting-edge deep learning and generative AI, you will expertly navigate the complexity of each problem, managing every phase from defining the challenge to deployment and iterative improvement. Your dedication to software engineering excellence will inform your thoughtful approach to system design for machine learning, encompassing data quality, pipeline design, feature workflows, model serving, and ongoing monitoring and enhancement. By integrating machine learning deeply within our cohesive product experiences, you will collaborate effectively with cross-functional teams, aligning on objectives, defining success metrics, and driving meaningful outcomes. You will stay informed about the rapidly evolving AI landscape, maintaining a discerning perspective that allows your team to focus on significant advancements while avoiding distractions. The Day to Day Design and implement ML-powered features for search, discovery, personalization, and more.

Join Arcade as a Senior Machine Learning Engineer, where you'll be at the forefront of AI innovation. In this pivotal role, you will leverage advanced machine learning algorithms to create and enhance cutting-edge solutions. Collaborate closely with cross-functional teams to drive impactful projects from ideation to deployment.

Join Retell AI as a Senior Full Stack Software EngineerAt Retell AI, we are revolutionizing the call center industry with innovative voice AI technology. Our cutting-edge solutions are designed to improve communication efficiency, allowing businesses to automate sales, support, and logistics calls that once required large teams of human agents. In just 18 months, we have experienced remarkable growth, achieving $36M in annual recurring revenue with a dedicated team of 20, up from $5M at the beginning of 2025.Our goal for 2026 is to create a modern customer experience platform powered entirely by AI. We are not just automating but building intelligent AI agents that can perform the roles of frontline agents, quality assurance analysts, and managers, continuously enhancing customer interactions.We are rapidly expanding and seeking talented individuals who are ready to solve challenging technical problems, work at a fast pace, and make a significant impact in one of the fastest-growing voice AI startups.Let’s shape the future of communication together!

About HexusAt Hexus, we are dedicated to unlocking the hidden potential of AI and personalization for businesses. Our passion lies in revolutionizing product-led growth, transforming how companies connect with their customers, thereby enhancing product adoption and ensuring long-term success. With a robust suite of AI-driven tools, Hexus enables businesses to optimize their PLG strategies across Sales, Marketing, and Customer Experience.Supported by leading investors, industry experts, and renowned angel investors, our team is spearheaded by former FAANG founders with extensive experience in SaaS, ML, and UX. Join us in our mission to redefine customer experiences through AI and personalization.Your RoleAs a dynamic, design-driven startup, we are seeking a talented Senior Product Engineer to join our early-stage team. You will be instrumental in actualizing our product vision by creating clean, intuitive UI and UX, developing robust editing tools, and ensuring top-notch performance. We seek an individual who raises the bar for what’s achievable online and is passionate about crafting exceptional responsive, interactive, and enjoyable user experiences.In this role, you will:Collaborate closely with the founding team to design engaging user experiences.Execute critical projects that empower our customers daily.Rapidly prototype and iterate on new features and functionalities, driving ongoing innovation.Architect efficient and reusable frontend systems that support complex web applications.Contribute to shaping the direction of our design-led product.Qualifications5+ years of experience in frontend development.Proficiency in front-end development using TypeScript, React, NextJS, and Node.js.Strong skills in design and styling with frameworks like Tailwind or Material Design.Comprehensive understanding of the entire web stack, including protocols and web server optimization techniques.Familiarity with modern deep learning models (GPT, LLAMA, BERT, Whisper, Stable Diffusion, etc.).Capacity to grasp user challenges and convert them into features and products.A desire to thrive in a fast-paced, iterative startup environment.

About Liquid AIFounded as a spin-off from MIT CSAIL, Liquid AI specializes in creating versatile AI systems designed for optimal performance across various deployment platforms, including data center accelerators and on-device hardware. Our technology emphasizes low latency, minimal memory consumption, privacy, and dependability. We collaborate with leading enterprises in sectors such as consumer electronics, automotive, life sciences, and financial services. As we experience rapid growth, we are on the lookout for exceptional talent to join our team.The OpportunityThe Data team at Liquid AI drives the development of our Liquid Foundation Models, focusing on pre-training, vision, audio, and emerging modalities. With the stagnation of public data sources, the effectiveness of our models increasingly relies on specially curated datasets. We are seeking engineers with a machine learning mindset who can efficiently gather, filter, and synthesize high-quality data at scale.At Liquid AI, we regard data as a research challenge rather than an infrastructural issue. Our engineers conduct experiments, design ablations, and assess how data-related decisions impact model quality. We will align you with a team where you can experience rapid growth and make a significant impact, be it in pre-training, post-training reinforcement learning, vision-language, audio, or multimodal applications.While we prefer candidates in San Francisco and Boston, we are open to considering other locations.What We're Looking ForWe are in search of a candidate who:Thinks like a researcher and executes like an engineer: You should be able to formulate hypotheses, conduct experiments, and evaluate results. Our engineers produce research-level code while our researchers implement production systems.Learns quickly and adapts: You will be working in rapidly evolving modalities, so the ability to quickly grasp new domains and thrive in ambiguity is essential.Prioritizes data quality: We hold data quality in high regard; tasks such as filtering, deduplication, augmentation, and evaluation are key responsibilities, not afterthoughts.Solves problems autonomously: Data engineers operate within training groups (pre-training and multimodal). While collaboration is crucial, we expect ownership and self-direction.The WorkDevelop and maintain data processing, filtering, and selection pipelines at scale.Establish pipelines for pretraining, midtraining, supervised fine-tuning, and preference optimization datasets.Design synthetic data generation systems utilizing large language models (LLMs), structured prompting, and domain-specific generative techniques.

About Taskrabbit:Taskrabbit is an innovative marketplace platform that seamlessly connects individuals with Taskers to manage everyday home tasks, including furniture assembly, handyman services, moving assistance, and much more.At Taskrabbit, we aim to transform lives one task at a time. We celebrate innovation, inclusion, and hard work, fostering a collaborative, pragmatic, and fast-paced culture. We seek talented, entrepreneurially minded, data-driven individuals who possess a passion for empowering others to pursue their passions. In partnership with IKEA, we are creating more opportunities for individuals to earn a consistent, meaningful income on their terms by establishing enduring relationships with clients in communities globally.Taskrabbit operates as a hybrid company, with team members located across the US and EU, and has been recognized as a Built In — Best Places to Work for 2022, 2023, and 2024, receiving accolades across various national and regional categories. Join us at Taskrabbit, where your contributions will be significant, your ideas appreciated, and your potential maximized!This position operates on a hybrid schedule, requiring two days of in-office collaboration per week. It can be based in our San Francisco office or our new New York City office (opening March 2026).About the RoleMachine Learning is a foundational element at Taskrabbit, and we are in search of an experienced Senior Machine Learning Engineer to join our team and help mold the future of ML/AI at Taskrabbit. This distinct, full-stack role is designed for someone who is enthusiastic about the entire machine learning lifecycle—from initial research and model development to constructing the robust infrastructure necessary for deploying and scaling your innovations.As a Senior Machine Learning Engineer, you will engage with exciting challenges that directly influence how users discover and interact with home services on the Taskrabbit platform. You will play a vital role in enhancing our capabilities in areas such as search ranking, content discovery, and recommendation systems. Collaborating closely with data scientists and fellow engineers, you will design and implement cutting-edge algorithms, ensuring the scalability, reliability, and optimization of our models in production alongside software engineers.

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.

Backend Software Engineer – AI Applications San Francisco Bay Area | Hybrid (3 days onsite, 2 remote)About TrueMeterAt TrueMeter, we are revolutionizing the way businesses manage their energy costs. The U.S. power grid was not designed for the AI era, and we are here to change that. With the rising demand for data centers and the lagging adoption of renewable energy, many businesses are facing increasing utility bills. Our solution? The AI Energy Agent—a system that simplifies and reduces energy costs by consolidating multiple utility bills into a single, affordable subscription. Since our MVP launch in May 2024, we have successfully onboarded millions in energy spending from notable brands. As a seed-stage startup backed by prominent Silicon Valley investors, we are poised for rapid growth.If you are passionate about developing AI-driven systems that can make a significant impact on the planet, we want to hear from you!The RoleWe are seeking a Backend Software Engineer (AI Applications) who thrives in fast-paced, early-stage environments. In this role, you will transform ideas and prototypes into functional systems in a matter of days.You will be responsible for creating the backend infrastructure that powers our AI Energy Agent, including LLM-driven systems that analyze, structure, and interpret energy data. This includes integrating with multiple utility APIs, managing data pipelines, and developing services that ensure our AI solutions are effective and reliable.You will collaborate closely with the co-founder/CTO and a talented team of engineers, designing scalable backend systems that can grow from 10 customers to 10,000, all while taking ownership of your work and delivering with pride.What You Will CreateAI-Driven Backends: Develop production systems that connect LLMs and coding agents to our data and product APIs.Service Architecture: Design and implement fast, secure microservices using Python (and optionally TypeScript).Data Integration: Build reliable connectors to energy company portals and public data sources.Infrastructure for Intelligence: Help architect the backend infrastructure that enables AI agents to read, reason, and act autonomously across our data stack.Performance & Scalability: Own systems that are designed to operate 24/7 with low latency and high reliability.

Dapster is actively seeking a Lead Hardware Engineer to become a pivotal part of our dynamic team. As a rapidly growing startup, this position offers the unique opportunity to influence our foundational technologies and products.About Dapster: We are dedicated to revolutionizing the market with AI-driven robotic picking solutions. Recently, we secured a significant pilot project with a top retailer, providing us with dilution-free funding to further develop our core technology.If you're eager to engage in innovative work alongside a talented and humble team, and want to share in the rewards of joining us at such an early stage, we’d love to hear from you!

Join Our MissionThe trucking and logistics sector is essential to our economy, yet its payment infrastructure is outdated and inefficient. At AtoB, we are on a mission to revolutionize payment systems for this industry. We've identified the challenges faced by hardworking professionals in trucking — from outdated tools to hidden fees, and we are committed to delivering solutions that prioritize their needs.About AtoBOur goal is to create a seamless payment experience akin to Stripe, tailor-made for the transportation industry. We understand the critical role of timely capital movement in supply chains and strive to ensure it happens smoothly and fairly. Every product we develop enhances user experience and works intelligently within the unique constraints our customers face daily, whether they are fleet managers or drivers.Our ExpertiseOur founding team boasts extensive experience in the tech and payments landscape, with backgrounds from industry leaders like Cruise Automation, Uber, Google, Meta, and Stripe. We've attracted over $125 million in funding from prominent investors, including General Catalyst, Y Combinator, and major tech founders, positioning us as a leader in innovation within our sector.Recognized by Forbes as one of the Next Billion-Dollar Startups, we are also proud to join the World Economic Forum as a Global Innovator.