Senior Software Engineer, Core Open-Source- Marimo

CoreWeave is The Essential Cloud for AI™. Built for pioneers by pioneers, CoreWeave delivers a platform of technology, tools, and teams that enables innovators to build and scale AI with confidence. Trusted by leading AI labs, startups, and global enterprises, CoreWeave combines superior infrastructure performance with deep technical expertise to accelerate breakthroughs and turn compute into capability. Founded in 2017, CoreWeave became a publicly traded company (Nasdaq: CRWV) in March 2025. Learn more at www.coreweave.com. About Marimo: At Marimo, we’re on a mission to make the world’s best open-source programming environment for working with data, together with a world-class, scalable, and performant cloud-hosted counterpart. marimo is a reinvention of the Python notebook — it feels like a next-gen reactive Python notebook, but is stored as pure Python that can be versioned with Git, deployed as a data app, run as a script, and reused as a module. Incubated initially with scientists at Stanford, marimo is now used by leading companies, labs, and universities around the world, with millions of downloads since launch and over 17,000 stars on our GitHub repository. On the Marimo team, we believe that the tools we use shape the way we think — better tools, for better minds. If you're passionate about developer tools, thrive in ambiguity, enjoy solving challenging engineering problems at scale, and yearn for greenfield problems, you'll fit right in. About the Team: The Marimo core open source team develops and maintains the marimo open source notebook. Today, this includes the marimo editor frontend, the marimo backend which includes the core dataflow compiler and runtime, an intermediary server, the marimo library, and an ecosystem of related projects, such as a VS Code extension, codemirror extensions, and more. This team has the crucial role of shepherding the future of one of Python's fastest growing and most impactful open-source projects. About the Role:  As a Senior Software Engineer on Marimo's core open source team, you’ll take ownership of projects across Marimo's open-source ecosystem, focusing on Marimo's backend and its Python ecosystem. You will influence critical decisions on library design, making sure our APIs remain simple yet composable; you'll also design new capabilities that push the boundaries of interactive computing without complicating the user experience. You'll work in the open, at a fast pace —  engaging promptly and empathetically with a large and vocal community of users and contributors, triaging their issues and reading between the lines to understand their unstated needs. All the while, you'll exercise judgment to balance the needs of our community with our own roadmap and vision. Who You Are:  4+ years of experience in software engineering Proficiency in Python, with strong fundamentals that are language agnostic Proficiency in computer systems, including parallel computing (threading, multiprocessing), concurrency (asynchronous programming), basic networking/inter-process communication Experience in library design and/or open-source development Strong communication skills, written and verbal Preferred:  A passion for and experience building developer tools, especially for AI, ML, or data A passion for working with data, with the ability to empathize with practitioners and researchers in AI, ML, data engineering, NLP, or other quantitative work An eye for visual and interaction design, with an emphasis on simplicity You find enjoyment in  connecting with users and community daily Proficiency in Typescript, or a willingness to learn Experience with AI engineering, including MCP and agents Experience with SQL, databases, and data engineering Experience with at least one systems language, such as C or Rust Wondering if you’re a good fit? We believe in investing in our people, and value candidates who can bring their own diversified experiences to our teams – even if you aren't a 100% skill or experience match. Here are a few qualities we’ve found compatible with our team. If some of this describes you, we’d love to talk.  You love crafting developer tools, especially for AI, ML, or data You’re curious about the day-to-day work of AI/ML/data engineers, researchers, and scientists You enjoy building in the open and engaging with your users The base salary range for this role is $165,000 to $242,000. The starting salary will be determined based on job-related knowledge, skills, experience, and market location. We strive for both market alignment and internal equity when determining compensation. In addition to base salary, our total rewards package includes a discretionary bonus, equity awards, and a comprehensive benefits program (all based on eligibility). What We Offer The range we’ve posted represents the typical compensation range for this role. To determine actual compensation, we review the market rate for each candidate which can include a variety of factors. These include qualifications, experience, interview performance, and location. In addition to a competitive salary, we offer a variety of benefits to support your needs. The benefits below reflect our US-based offerings; for roles in other locations, benefits vary and are shared during the hiring process. These include: Medical, dental, and vision insurance - 100% paid for by CoreWeave Company-paid Life Insurance  Voluntary supplemental life insurance  Short and long-term disability insurance  Flexible Spending Account Health Savings Account Tuition Reimbursement  Ability to Participate in Employee Stock Purchase Program (ESPP) Mental Wellness Benefits through Spring Health  Family-Forming support provided by Carrot Paid Parental Leave  Flexible, full-service childcare support with Kinside 401(k) with a generous employer match Flexible PTO Catered lunch each day in our office and data center locations A casual work environment A work culture focused on innovative disruption California Ap