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OnlinePy
What OnlinePy is
OnlinePy is a free Python IDE that runs code directly in a browser, without installation or an account. Code executes locally through WebAssembly, and the maker says it remains on the device unless Share is used. The environment supports NumPy, Pandas, Matplotlib, SciPy, and scikit-learn through Pyodide, while most pure Python packages on PyPI can be installed at runtime. The site advertises approximately 4GB of WebAssembly heap. Runs are logged automatically, with one-click rollback to an earlier point, and code can be exported as an image with syntax highlighting and terminal output. Projects may stay private or use link access for sharing. OnlinePy can be embedded as a floating widget, JavaScript custom element, or iframe. After the initial Pyodide download, later visits can work offline from cache. It works in modern mobile browsers, though desktop or laptop use is recommended.
Who it suits
OnlinePy suits learners, teachers, interview candidates, data analysts, and anyone testing Python snippets without creating an account. It also fits users who want browser-based local execution or embeddable examples.
What it does well
- Free plan at no cost
- No installation or account required
- Local WebAssembly execution
- Supports common scientific Python libraries
- Automatic run history and rollback
What to know first
- No full-stack runtime
- No deployment options listed
- Iframe input() and Stop can be limited
- Desktop or laptop recommended
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Free | Browser-based Python IDE · Local WebAssembly execution · No account required · No ads | Free |
| OnlinePy | Free · no ads · no login | Free |
As onlinepy.com lists them, read 23 Sept 2026. The maker's own page has the final word.
Verdict
OnlinePy provides a no-login browser workspace for writing and running Python locally.
Facts from OnlinePy's own pages
- Audience
- The homepage lists testing snippets, learning Python, data analysis, coding interview preparation, and teaching as use cases. · onlinepy.com, 11 Oct 2026
- Code history
- The homepage describes automatic logging of runs and one-click rollback to an earlier point. · onlinepy.com, 11 Oct 2026
- Deployment options
- none · onlinepy.com, 23 Sept 2026
- Embedding
- OnlinePy can be embedded using a floating widget, JavaScript custom element, or iframe, with configurable visible features. · onlinepy.com, 11 Oct 2026
- Embedding limitation
- In an iframe without cross-origin isolation, code can still run, but interactive input() and Stop are limited. · onlinepy.com, 11 Oct 2026
- Free plan
- Yes · onlinepy.com, 23 Sept 2026
- Full-stack runtime
- No · onlinepy.com, 23 Sept 2026
- Image export
- Users can export code with syntax highlighting and terminal output as an image. · onlinepy.com, 11 Oct 2026
- Libraries
- It supports NumPy, Pandas, Matplotlib, SciPy, and scikit-learn through Pyodide. · onlinepy.com, 11 Oct 2026
- Local execution
- Code executes locally in the browser using WebAssembly, and the maker says code stays on the device unless the user uses Share. · onlinepy.com, 11 Oct 2026
- Maker details
- The About page identifies the product as OnlinePy but does not state a maker name, headquarters, or founding date. · onlinepy.com, 11 Oct 2026
- Memory
- The site advertises up to approximately 4GB of WebAssembly heap. · onlinepy.com, 11 Oct 2026
- Mobile support
- The maker says OnlinePy works in modern mobile browsers and recommends desktop or laptop for the best experience. · onlinepy.com, 11 Oct 2026
- Offline use
- The About page says that after the initial Pyodide runtime download, subsequent visits can work offline from cache. · onlinepy.com, 11 Oct 2026
- Package installation
- The maker says most pure Python packages on PyPI can be installed at runtime. · onlinepy.com, 11 Oct 2026
- Platform
- OnlinePy is described as browser-based; no native desktop or mobile app is identified on the pages opened. · onlinepy.com, 11 Oct 2026
- Private projects
- Yes · onlinepy.com, 23 Sept 2026
- Purpose
- OnlinePy is a Python IDE that runs code in the browser without installation or an account. · onlinepy.com, 11 Oct 2026
- Sharing controls
- link_access · onlinepy.com, 23 Sept 2026
Where OnlinePy stands on Freedom251
- Coding Playgrounds#81 of 138