Jobs in United States

Machine Learning Manager in San Mateo

60 active opportunities · Updated October 2026

Explore current machine learning manager jobs in San Mateo. Filter by work mode, employment type, experience, department, date posted and distance.

R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $345K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences – all created by our global community of developers and creators. At Roblox, we're building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We're on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you'll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Why Safety AI Systems? As Senior Engineering Manager for Safety AI Systems at Roblox, you'll lead technical efforts and manage a team of experienced engineers to develop innovative AI solutions for language and text content safety. You'll oversee machine learning systems, data quality, training pipelines, and model performance to address challenges like real-time content understanding across Roblox's experiences

AWSGitMachine LearningAI
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $295.3K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Why Safety AI Systems? As Senior Engineering Manager for Safety AI Systems at Roblox, you'll lead technical efforts and manage a team of experienced engineers to develop innovative AI solutions for multimodal content safety. You’ll oversee machine learning systems, constructing multimodal model architectures, improving data quality, training pipelines, and model performance to address challenges like real-time multi-verse content understanding and advanced moderation with large vision language models, spanning avatars, images, videos, audios, text, code / data models, and their composites. In close collaboration with product, policy, and Trust & Safety teams, you'll design large-scale systems to detect and mitigate abusive behavior before it harms the community. You'll own critical services at massive scale, balancing user freedom with platform civility to protect and empower our users. Your leadership will help ensure Roblox remains a safe, inclusive space for self-expression and shared experiences. You Will Own the vision, technical direction, and execution of machine learning solutions for the Multimodal Safety AI system, ensuring these systems effectively detect and prevent ha

AWSGitMachine LearningAI
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $295.3K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. With Roblox Ads business growing at a rapid rate, we are building large scale ads machine learning infrastructure to deliver effective performance ads to our users, and more business values to our advertisers. We’re looking for an EM to lead a team of exceptional ML infrastructure engineers, build scalable, reliable, and high-performance infrastructure that powers ML systems across our organization. You’ll operate at the scales of hundreds of billions of engagements, and redefine how we deliver performance ads to hundreds of millions of users. You Will: Lead strategic planning and roadmap execution of scalable production-ready ML systems including model training, data pipelines, feature engineering and model inference. Own the architecture, establish engineering best practices of scalability, reliability, and cost-effectiveness of ML infrastructure (e.g., training, serving, feature). Work closely with data scientists, ML engineers, platform teams, and product stakeholders to design, implement, and operate robust ML platforms that accelerate model development and deployment. Recruit, mentor, and grow a high-performing team of ML infrastructure engineers. You Have: 5+ years of experienc

AWSGitMachine LearningAI
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $345K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. The mission of the search and discovery team is to connect a billion users with the best connections and content at the right time, covering an extremely diverse range of recommendations and search problems at high scale. This is fundamental to how we personalize the experience to drive engagement and retention for Roblox users. Our recommendation systems suggest all games that the users see and play with across all surfaces. As a Senior Engineering Manager for the Search & Discovery ML team, you will lead the architects of exploration for one of the world's largest immersive platforms. You will be responsible for the core algorithms that connect over 120 million daily active users with millions of 3D experiences, items, and social connections. This is a high-impact leadership role where your team’s models directly determine the growth, retention, and satisfaction of the Roblox community. You will move beyond traditional recommendation systems into the realm of multimodal, agentic, and generative discovery . You Will: Lead and grow a high-performing team of machine learning engineers, fostering a culture of ownership, collaboration, and engineering excellence. Establish a lo

AWSGitMachine LearningAI
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $345K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Senior Engineering Manager, Safety Platform You will lead engineering pods within the Safety Platform organization, driving the technical vision and execution for the foundational systems that power every safety workflow at Roblox. You will own the core safety platform end-to-end: from the shared infrastructure and APIs that enable trust & safety capabilities across the company, to the tooling ecosystem that empowers internal operators to investigate, intervene, and resolve issues at scale. The scope also includes the Safety agentic platform — AI-powered systems that automate and augment safety workflows across detection, enforcement, and review pipelines. As the platform layer beneath every safety surface, your work will define how quickly and reliably Roblox can respond to emerging threats. This role requires a leader with a strong platform mindset who can balance technical rigor with broad organizational impact — working across User Safety, Trust & Safety Policy, Data Science, and Machine Learning to deliver scalable, extensible, and high-availability systems for one of the world's largest platforms. You Will: Lead and Develop: Recruit, hire, mentor, and inspire a diverse team of

AWSGitMachine LearningAI
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $280.5K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Every day, Roblox users play over 7M experiences, make over 270M avatar updates, send 6+ billion chat messages and talk for 1+ million hours using voice. Safety is Roblox’s top priority. As part of the Safety Group, the Content and Communications Safety team builds AI features and tools to automate review and moderation of all of these activities on the platform. Areas that the Content Safety Team works on include: Experience reviews The components that make up those experiences (textures, 3D meshes, models, scripts) Avatars, Avatar items Audio, Video Text chat and voice conversations and other content types As a Senior Product Manager on the team, you will work closely with leadership, product, engineering, data science, and operations teams across Roblox. In addition, you will drive critical company-level KPIs that affect how Roblox keeps the platform safe and civil. As we bring new immersive features and content types to Roblox, you will be responsible for leading the product in one of the most challenging and vital roles at Roblox. You will Lead safety features focused on automation of content reviews by leveraging AI Stay one step ahead of malicious actors and their adversarial tactics

AWSGitMachine LearningAI
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $295.3K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Engineering Manager, Home Infrastructure The Home Infrastructure team builds the mission-critical backend and data systems that power Roblox’s Homepage and Experience Details Page, two of the highest-traffic surfaces on Roblox. These surfaces reach the vast majority of Roblox’s daily active users and are core drivers of discovery, engagement, retention, and platform growth. We are a full-stack product infrastructure team responsible for content distribution across Roblox. Our systems support multiple modes of user interaction, including exploratory browsing, directed discovery, and personalized content recommendations across the many types of content that make up the Roblox ecosystem. This team sits at the intersection of large-scale distributed systems, machine learning-powered personalization, data infrastructure, and product experimentation. We partner closely with Machine Learning, Data Science, Product, Design, Frontend, Ads, Marketplace, Virtual Economy, and other teams across Roblox to build the platforms that help users find the most relevant and engaging content. As Engineering Manager for Home Infrastructure, you will lead a team of Backend and Data Engineers responsible for the e

AWSGitMachine LearningAI
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $295.3K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Engineering Manager, Home Infrastructure The Home Infrastructure team builds the mission-critical backend and data systems that power Roblox’s Homepage and Experience Details Page, two of the highest-traffic surfaces on Roblox. These surfaces reach the vast majority of Roblox’s daily active users and are core drivers of discovery, engagement, retention, and platform growth. We are a full-stack product infrastructure team responsible for content distribution across Roblox. Our systems support multiple modes of user interaction, including exploratory browsing, directed discovery, and personalized content recommendations across the many types of content that make up the Roblox ecosystem. This team sits at the intersection of large-scale distributed systems, machine learning-powered personalization, data infrastructure, and product experimentation. We partner closely with Machine Learning, Data Science, Product, Design, Frontend, Ads, Marketplace, Virtual Economy, and other teams across Roblox to build the platforms that help users find the most relevant and engaging content. As Engineering Manager for Home Infrastructure, you will lead a team of Backend and Data Engineers responsible for the e

AWSGitMachine LearningAI
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $216.2K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Roblox is building the future of human connection through play. As a Senior Growth Marketing Manager, you will play a critical role in scaling Roblox's global growth engine, helping millions of users discover, engage with, and return to Roblox. This role sits at the intersection of marketing, product, data science, and engineering. You will lead high-impact growth initiatives spanning user acquisition, lifecycle marketing, personalization, creator growth, and product-led growth. You will be responsible for identifying new growth opportunities, designing and executing experiments, influencing product strategy, and scaling programs that drive measurable business impact. This is a highly cross-functional role for someone who combines analytical rigor, strong growth instincts, operational excellence, and the ability to influence across teams. You will report to the Head of Growth Marketing. You will: Own and Scale Growth Programs Lead end-to-end growth initiatives across user acquisition, reactivation, paid influencer, and product-led growth programs. Manage and optimize multimillion-dollar marketing investments across ad platforms including but not limited to Google, YouTube, Meta, TikTo

ReactSQLAWSGit
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $176.5K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Roblox is building the future of human connection through play. As a Senior Growth Marketing Manager, you will play a critical role in scaling Roblox's global growth engine, helping millions of users discover, engage with, and return to Roblox. This role sits at the intersection of marketing, product, data science, and engineering. You will lead high-impact growth initiatives spanning user acquisition, lifecycle marketing, personalization, creator growth, and product-led growth. You will be responsible for identifying new growth opportunities, designing and executing experiments, influencing product strategy, and scaling programs that drive measurable business impact. This is a highly cross-functional role for someone who combines analytical rigor, strong growth instincts, operational excellence, and the ability to influence across teams. You will report to Sr Manager, Growth Marketing. You will: Own and Scale Growth Programs Lead end-to-end growth initiatives across user acquisition, reactivation, paid influencer, and product-led growth programs. Manage and optimize multimillion-dollar marketing investments across ad platforms including but not limited to Google, YouTube, Meta, TikTok, App

ReactSQLAWSGit
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $243.3K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. The Data Engineering team at Roblox plays a fundamental role in enabling the company's success by developing and maintaining highly leveraged Core Data Sets, frameworks, and tooling to support the growing demand for analytics. As a Senior Data Engineer, you will work to define the data ontology for all of Roblox, establish standard methodologies for data operations and lifecycle management, design and build analytics tooling and frameworks, and influence event instrumentation. Additionally, this role is highly multi-functional, requiring close collaboration with Data Science, Experimentation, and Machine Learning teams to understand customer requirements and analytics applications, as well as with Data Infrastructure and Storage teams to develop integrated solutions. Join us and be a part of a dynamic team driving innovation and growth at Roblox. This role will report to our Engineering Manager on the Data Engineering team. You Will: Partner with Data Science, Product, and Engineering to collect requirements to define the data ontology for all of Roblox Lead and mentor a growing team of Data Engineers to support Roblox's ever-evolving data needs Design, build, and maintain efficient an

SQLAWSAzureGCP
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $295.3K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. The Data Engineering team at Roblox plays a crucial role in enabling the company's success by developing and maintaining highly leveraged Core Data Sets, frameworks, and tooling to support the growing demand for analytics. As a Principal Data Engineer, you will work to define the data ontology for all of Roblox, establish best practices and standards for data operations and lifecycle management, design and build analytics tooling and frameworks, and influence event instrumentation. Additionally, this role is highly cross-functional, requiring close collaboration with Data Science, Experimentation, and Machine Learning teams to understand customer requirements and analytics applications, as well as with Data Infrastructure and Storage teams to develop integrated solutions. Join us and be a part of a dynamic team driving innovation and growth at Roblox. You Will: Partner with Data Science, Data Platform, Product, and Engineering to collect requirements to define the data ontology for all of Roblox Lead and mentor a growing team of Data Engineers to support Roblox's ever-evolving data needs Design, build, and maintain efficient and reliable batch and streaming data pipelines to mod

SQLAWSAzureGCP
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $278.5K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. ML Platform @ Roblox today supports hundreds of ML use cases and billions of inferences per day across Discovery, Safety, Engine, and much more. As an Infrastructure Engineer on the ML Platform team, you will design, scale, and maintain the foundational infrastructure powering our entire machine learning ecosystem. We are looking for accomplished engineers to spearhead the development of our next-generation ML tooling and platform capabilities. You will: Bootstrap and maintain Kubernetes and Cloud infrastructure for ML Platform components--Serving Layer, Metadata Store, Model Registry, and Pipeline Orchestrator. Set technical strategy and oversee development of high scale and reliable infrastructure systems. Propose and implement new platform tooling to improve time to production for MLEs and Data Scientists across the full ML lifecycle. Work on infrastructure projects such as GPU fleet management, hybrid-cloud orchestration, and writing custom Kubernetes controllers and resources. Stay abreast of industry trends in machine learning and infrastructure to ensure the adoption of leading-edge technologies and practices. Partner across organizations to build tooling, interfaces, and visualizati

AWSGCPDockerKubernetes
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $278.5K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. With Roblox’s daily active users growing at a record pace, we are seeking experienced machine learning researchers who thrive on solving complex challenges and designing scalable, ground breaking solutions. In this role, you will innovate on LLMs, VLMs, autoregressive models, or other large models for user understanding, content understanding, recommendation, and agentic search. Your work will lay the foundation for personalizing user experiences, enhancing engagement and retention, and driving growth within the creator ecosystem. In search and discovery, you will contribute to the core systems that enable users to discover and interact with experiences across Roblox. These systems drive exploration and engagement across all surfaces, helping users find relevant and exciting content. Looking ahead, our team aims to innovate further by developing auto-generated summaries, images, and videos from experience content to improve discoverability and inspire user exploration. Our mission is to connect a billion users with the best content and connections at the right time, tackling diverse challenges in advertising, search, and discovery at an unprecedented scale. Join us and play a pivotal role i

AWSGitMachine LearningAI
R
📍 San Mateo, CA, United States· Full-time
✓ High-confidence listingCompany trend -100%

From $295.3K/yr

Quick readStrong listing-quality and freshness signals

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators. At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there. A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone. Why Content Safety? As a Principal Machine Learning Engineer for Content Safety, you will define the future of proactive moderation, driving immense social impact through cutting-edge, innovative ML solutions, focused on critical and ambiguous safety challenges. You will set the 3-5 year technical strategy and architectural blueprint for how Roblox uses machine learning for content moderation. You will own the architectural and execution roadmap of massive-scale ML systems that mitigate violative UGC content before it impacts our community. You will feel a deep sense of responsibility in proactively protecting our community thoughtfully and fairly, while balancing user freedom with platform civility. Your efforts will ensure Roblox remains one of the safest places on the internet for our broad community of over 100 million daily active users. You will: Define and Own the Technical Vision: Define and lead the multi-year technical vision, architectural strategy, and execution for machine learning solutions in Content Safety, ensuring these systems proactively and effectively detect and mitigate violative content at massive scale. Strategic Stakeholder Partnership: Collaborate with execu

AWSGitMachine LearningAI
🔔

Get new machine learning manager jobs in San Mateo, United States by email

Daily job updates · Unsubscribe anytime