marimo
by marimo (acquisition by CoreWeave announced October 2025) · Application
Reactive Python notebook stored as a plain .py file that re-runs dependent cells automatically and doubles as a script or web app
Overview
marimo is an open-source reactive notebook for Python released under Apache 2.0. Instead of a JSON document, a marimo notebook is an ordinary Python file in which each cell is a function; marimo analyzes variable references to build a dependency graph, so changing a cell re-executes exactly the cells that depend on it (or marks them stale in lazy mode), and the file can be run as a script, imported as a module, deployed as an interactive web app or exported to HTML, WebAssembly or an .ipynb. Built-in UI elements (sliders, tables, forms), a SQL cell backed by DuckDB, native display of pandas and Polars DataFrames, a package-aware sandbox with uv, and an AI-assisted editor are part of the base install, and marimo can also open and convert Jupyter notebooks.
In October 2025 CoreWeave announced an agreement to acquire marimo Inc., stating that the open-source notebook would remain available under its permissive license. marimo attracts users who want reproducible, version-controllable notebooks; constraints are Python-only kernels, the rule that a variable may be defined in only one cell, and a younger ecosystem than Jupyter's.
Editorial note on uncertainty. Hosted marimo offerings were not reviewed; pricing_model reflects the open-source notebook only.
Capabilities
- Reactive execution driven by a static dependency graph
- Notebooks stored as plain Python files (git-friendly)
- Run as script, app or export to HTML, WASM or ipynb
- Built-in UI widgets, SQL cells (DuckDB) and DataFrame viewers
- Package sandboxing with uv
- AI-assisted cell generation
Typical workflows
- Reproducible analysis committed to git without output noise
- Turn an exploratory notebook into an internal web app
- Interactive teaching material with sliders and live plots
Strengths
- Deterministic execution and no hidden state
- Clean diffs and importable code
- Apache 2.0 with active development
Limitations
- Python only
- Each variable may be defined once across the notebook
- Smaller extension ecosystem than Jupyter
Prerequisites
- Python 3 (pip or uv install marimo)
Who it is for
- Data scientists and researchers
- Instructors
- Python developers building small apps
Alternatives & comparison
- Observable
JavaScript data notebooks and the open-source Observable Framework static-site generator for data apps, from the maintainers of D3 and Plot
MixedFreemium - Positron
Posit's multi-language data-science IDE built on Code OSS, with first-class R and Python consoles, variables and plots panes, under the Elastic License 2.0
Source-availableFree - Project Jupyter
Open-source computational notebook ecosystem: the .ipynb format, kernels for Python, R and Julia, JupyterLab and Notebook interfaces and JupyterHub
Open sourceOpen source - Quarto
Open-source scientific publishing system from Posit that renders Markdown with executable Python, R, Julia or Observable code to HTML, PDF, Word, slides, websites and books via Pandoc
Open sourceFree
Sources & verification
Primary sources consulted for this record. Claims are tied to the fields each source supports; the automated link checker re-verifies every URL on a schedule.
- Licensemarimo LICENSE (Apache 2.0)checked Nov 1, 2026
https://github.com/marimo-team/marimo/blob/main/LICENSE
Supports: license_spdx, source_model
- NewsCoreWeave acquires marimo (announcement, 2025-10-30)checked Nov 1, 2026
https://coreweave.com/news/coreweave-acquires-marimo-to-unify-the-generative-ai-developer-workflow
Supports: vendor
- Official documentationchecked Nov 1, 2026
- Official sitechecked Nov 1, 2026
- Repositorychecked Nov 1, 2026
- Confidence
- High
- Reviewed
- Nov 1, 2026
- Links
- Verified · Nov 2, 2026