The archive · Developer & Business Tools · Product decision · 2022–2025
Marimo's reactive-notebook bet: $5M seed, 22.6k stars, then CoreWeave
Marimo bet a reactive, Git-friendly Python notebook would beat Jupyter's hidden-state bugs; after 22.6k stars and a $5M seed, CoreWeave acquired it in 2025.
Marimo Inc.
What the business is
Marimo builds an open-source reactive notebook for Python: cells recompute automatically when their inputs change, notebooks are stored as pure Python, and they run as scripts, web apps or interactive documents.
Starting capital：$5M seed led by AIX Ventures (Anthony Goldbloom, Shyam Mani) announced Nov 2024, with angels incl. Jeff Dean, Clement Delangue and Wes McKinney; acquisition terms undisclosed.
How it started
Akshay Agrawal (ex-Google Brain, Stanford PhD, CVXPY maintainer) started marimo in 2022 out of Jupyter frustration; with co-founder Myles Scolnick (ex-Palantir, CloudKitchens) he launched publicly in January 2024 after incubating with Stanford's SLAC, and the launch became the second-highest Python Show HN of all time.
What happened
By Nov 2024 marimo had 7.8k stars, 60+ contributors and 1M+ downloads in 10 months, so the two-person team raised a $5M seed led by AIX Ventures with angels including Jeff Dean and Wes McKinney. Through 2025 growth continued: 1M+ monthly downloads, 16.6k stars, ~200 contributors, a WebAssembly build, the molab hosted notebook, and a Nature feature.
How it ended up
On 2025-10-30 CoreWeave announced a definitive agreement to acquire Marimo Inc. The whole 8-person team stayed, molab was re-hosted on CoreWeave's cloud, and the notebook remains free and Apache-2.0 licensed.
Background
Marimo is an open-source reactive notebook for Python, created as a direct answer to Jupyter's most-criticized flaw: hidden state. Cells recompute automatically when their inputs change, notebooks are stored as pure Python instead of JSON, and the same file can be a script, a module, an interactive app or a web page.
Akshay Agrawal, a Stanford PhD and Google Brain alum who maintained CVXPY, started building it in 2022 out of personal frustration; he and Myles Scolnick launched publicly in January 2024 after incubating with Stanford's SLAC, and the launch became the second-highest Python Show HN of all time. By November 2024 the project had 7.8k stars and 1M+ downloads, and the two founders raised a $5M seed led by AIX Ventures.
Growth kept compounding through 2025 — 1M+ monthly downloads, 16.6k GitHub stars (more than Jupyter's core repo, per the company), ~200 contributors, a WebAssembly build, and the molab hosted notebook. On October 30, 2025, CoreWeave announced a definitive agreement to acquire Marimo Inc.; the whole eight-person team stayed, molab moved onto CoreWeave's cloud, and the notebook remained free, open source and Apache-2.0 licensed.
What has to be true
- The bet was falsifiable: Jupyter's hidden state was a universal, documented pain — over a third of 10M public notebooks fail to reproduce.
- Storing notebooks as pure Python removed the ecosystem friction, so marimo could be adopted incrementally inside existing Python codebases.
- Open source was the distribution engine: the HN launch plus GitHub trending did the marketing, growing stars 7.8k to 22.6k with a two-to-eight-person team.
- The acquisition rewarded the community, not the seats: CoreWeave bought the default open-source notebook of the AI/data generation to anchor its cloud.
What can be applied
An open license and a better interaction model built the asset acquirers pay for: marimo never sold seats, yet its stars and contributors became the product CoreWeave wanted.
Aftermath
As of 2026-09-02 marimo is developed inside CoreWeave, which keeps it free, open source and Apache-2.0 licensed: the repository stands at 22.6k stars with global rank #1891, and the team continues shipping releases while molab runs on CoreWeave Cloud. CoreWeave announced the deal on 2025-10-30 as part of a 2025 acquisition spree that also included Weights & Biases, OpenPipe and Monolith AI; terms were undisclosed, and the eight-person marimo team stayed together under CoreWeave.
Sources
- Announcing Marimo Inc.
- Marimo is Joining CoreWeave
- CoreWeave adds Marimo to their 2025 acquisition spree
- marimo-team/marimo — Stars, Trending & Rank
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