nbview

A client-side Jupyter notebook viewer for public GitHub repos. No server: the browser fetches the .ipynb straight from GitHub and renders it, so there's nothing to crash or queue.

Live at nbview.org

What it does

• Browse any user, org or repo (chizkidd, owner/repo, or a pasted GitHub URL)
• Render .ipynb files: markdown, LaTeX (KaTeX), syntax-highlighted code, text, HTML tables, images, SVG, ANSI-colored tracebacks, progress bars
• Inspired by nbviewer: Jupyter classic typography, Pygments-style Python colors, upright math, and long equations that wrap instead of running off the page
• Open notebooks from any direct .ipynb URL that allows cross-origin reads, from a gist link, or from a local file
• nbviewer links work too: paste one into the box, or just change nbviewer.org to nbview.org in the address bar
• Shareable URLs, e.g. nbview.org/github/owner/repo/blob/main/path/to/notebook.ipynb (the #/github/... form works too), with a preview card (file name and repo) when pasted into Slack, Reddit, X and similar, plus a "Copy link" button on every notebook and a # button on every cell that copies a link straight to that cell (...?cell=12)
• A Contents menu built from the notebook's headings, plus hide code, hide outputs, line numbers, wrap long lines, download, open in Binder (standard JupyterLab, so widgets work) or Colab
• Compare notebooks: use Compare on any GitHub notebook (pick a branch, tag or commit, one of the file's recent commits, or a different notebook), on a gist (earlier revisions), on a local file or a notebook opened by URL; or compare any two notebooks by link, gist link or owner/repo/path.ipynb (different repos and branches are fine), or two local files. Changed lines highlight the changed words Changes show cell by cell, in one column (unified) or side by side, with optional output changes
• Plotly charts can run: a chart that was saved with its data shows a "Run interactive chart" button, and clicking it zooms, pans and hovers inside an isolated frame (off until you click)
• Export a notebook as a Python script, Markdown, a standalone HTML page, or a PDF (via your browser's print dialog), all built locally in your browser
• Light and dark mode, following your system until you pick one

nbview is an independent project and is not affiliated with Project Jupyter or nbviewer.

Limits

• Folder browsing and gists use the GitHub API: 60 requests/hour per IP without a token. Add a no-scope token via the "GitHub token" button for 5,000/hour. Opening notebooks uses raw.githubusercontent.com and doesn't count.
• API responses are cached for 5 minutes in the tab (sessionStorage), so going back to a folder you just viewed doesn't use up the limit.
• Notebook JavaScript is never executed. Bokeh outputs are skipped, and ipywidgets show only their saved state, read-only (progress bars, labels, HTML, values; open the notebook in Binder or Colab to use them); static images, tables and text render normally. The one exception is Plotly figures that were saved as data: they only run after you click "Run interactive chart", inside a frame the browser isolates from this page (no access to your tokens, storage, cookies or the page, and no network), using the Plotly library served from this site. Charts over about 3 million values or with more than 200 traces don't run, and at most 8 run at once.
• HTML in notebooks is sanitized: scripts, forms and form controls are removed, and author CSS is limited to colors, borders, fonts and layout (no positioning, no url()), scoped to the cell it came from. Only http and https notebook links are accepted.
• Size limits keep one cell from freezing the tab: notebooks over 10 MB (including local files) ask before opening, outputs over 1 MB sit behind a "Show output" button, code cells over 200 KB are shown without syntax colors, and equations over 4,000 characters or 40 levels of nesting, or beyond the first 2,000 in a notebook, are shown as plain TeX. A cell that fails to render is replaced by a notice with its raw source.
• Safari is slower than Chrome and Firefox on very large notebooks: about 3x slower for thousands of cells, and a single markdown cell with over 1 MB of text and no spaces or line breaks can freeze the tab for many seconds.
• Public repos only.

Privacy

• Notebooks are fetched and rendered in your browser. There is no nbview server that sees them. Link previews are built from the address alone (file name and repo), never from the notebook's contents.
• Remote images in a notebook load from whatever host the notebook points at, so that host can see your IP address. Everything else (scripts, math fonts, page fonts) is served from nbview.org itself.
• The optional GitHub token and your recently opened list stay in this browser's local storage. The token is sent only to api.github.com.
• nbview.org uses Cloudflare's privacy-focused analytics (page views, no cookies).

Development

There is no build step: the repo is served as-is by Cloudflare Pages, and every push to main deploys to nbview.org.

Folder structure

nbview/
├── index.html           page shell and static home text
├── _redirects           nbviewer-style /url and /urls paths -> /#/... routes (the domain swap)
├── functions/           /github and /gist paths: redirect to the viewer, and answer link-preview crawlers with a card made from the link
├── _headers             security headers: strict CSP (no forms, only this site can frame it, scripts from this site only)
├── sandbox/plotly/      the page inside the isolated chart frame
├── robots.txt           allow all crawlers, points to the sitemap
├── llms.txt             plain-language summary and link formats for AI agents (llmstxt.org)
├── sitemap.xml          the home page
├── .well-known/
│   └── security.txt     how to report a security problem
├── assets/
│   ├── css/style.css
│   ├── js/
│   │   ├── app.js       routing, GitHub fetching, notebook rendering
│   │   ├── export.js    builds the .py, .md and .html exports
│   │   ├── diff.js      cell and line diff used by Compare
│   │   └── theme.js     restores light/dark theme before first paint
│   ├── fonts/           JetBrains Mono and Source Serif 4 (self-hosted, Latin)
│   ├── vendor/          marked, DOMPurify, highlight.js, KaTeX, served from this site (no CDN)
│   ├── og-light.png     1200x630 link-preview image (og-dark.png is the dark variant)
│   └── og-dark.png
├── tests/               regression tests (Playwright)
├── package.json         dev dependencies for the tests only
├── CHANGELOG.md
├── MAINTENANCE.md       yearly and per-release chores
├── LICENSE
└── README.md

Run locally

python -m http.server in this folder, then open http://localhost:8000. The _redirects rules and the functions/ link previews only apply on Cloudflare Pages, not locally.

Tests

npm install && npx playwright install chromium && npm test. More options (other browsers, a single test, the live smoke test) are in tests/README.md.

Upkeep

Yearly and per-release chores are in MAINTENANCE.md.

See CHANGELOG.md for what changed in each release.