Jupyter Notebooks, opened in a click.
A zero-dependency browser extension that opens, renders, and edits
.ipynb files directly in your browser.
No Jupyter server. No Python install. Just open and read.
Beautifully rendered cells, instantly.
Markdown, syntax-highlighted Python, base64 PNG/JPEG/GIF, inline SVG, HTML tables, ANSI tracebacks with full 256-color support — all rendered locally inside your browser.
Built-in markdown parser (headings, lists, tables, math, code fences) Python syntax highlighter with keywords, strings, decorators ANSI parser with bold / italic / underline support Drop a file onto the viewer to open it instantly
Customer churn analysis
A quick look at the monthly retention numbers.
import pandas as pd import matplotlib.pyplot as plt # Load the dataset df = pd.read_csv("customers.csv") churn = df[df["churned"] == 1] print(f"Churn rate: {len(churn)/len(df):.2%}")
Everything a notebook needs.
Nothing it doesn't.
No tracking, no telemetry, no third-party scripts. Just an honest viewer.
Instant rendering
Open any .ipynb and see formatted markdown, syntax-highlighted code, and rich outputs immediately.
Auto-open
Navigate to any notebook URL — local or remote — and the extension intercepts and renders it automatically.
13 built-in themes
Dracula, Tokyo Night, Ayu, Nord, Solarized and more. System-aware default — Ayu for dark, GitHub for light.
Inline editing
Click Edit on any cell to modify its source. Tab inserts 4 spaces. Save commits, Cancel discards. Download exports the notebook.
Rich outputs
Streams, execution results, HTML tables, error tracebacks with full ANSI colors (256-color), base64 PNG/JPEG/GIF, inline SVG.
Drag & drop
Drop a notebook file onto the viewer page to open it instantly. No upload, no server — everything stays local.
Pick a vibe.
Set it once. It sticks.
From soft cream to deep purple — 13 carefully crafted themes baked in. Your selection persists across sessions.
Click a theme — preview live.
All 13 themes re-render the demo notebook instantly. No install needed.
import pandas as pd import matplotlib.pyplot as plt # Load the dataset df = pd.read_csv("customers.csv") churn = df[df["churned"] == 1] print(f"Churn rate: {len(churn)/len(df):.2%}")
def greet(name): return f"Hello, {name}!" greeting = greet("world") print(greeting)
def greet(name): return f"Hello, {name}!" greeting = greet("world") print(greeting)
Privacy first.
JpyLens processes everything entirely inside your browser. No upload, no transmission, no analytics, no telemetry. Your theme preference and line-number toggle are the only things stored — locally, via storage.local.
Engineered light.
Manifest V3 (Chrome) and V2 (Firefox). Zero npm packages, zero CDN, zero build step — every parser, syntax highlighter, and ANSI handler is hand-written vanilla JavaScript bundled inside the extension.
Frequently asked questions
Everything people ask before installing.
Do I need Python or Jupyter installed to use JpyLens?
No. JpyLens renders and edits .ipynb files entirely inside your browser. There's no Python runtime, no Jupyter server, no kernel — it just reads the notebook JSON and renders the cells.
Can JpyLens execute notebook code?
JpyLens is a viewer and editor, not a kernel. It renders any output that's already saved in the notebook (text, HTML, images, ANSI tracebacks) and lets you edit cell source — but it does not run code. Pair it with Jupyter when you need to execute cells.
Does JpyLens send my notebooks anywhere?
No. Everything is processed locally in your browser. There are no analytics, no telemetry, and no remote requests. Only your theme preference and a few UI flags are saved to storage.local.
Which browsers does JpyLens support?
Chrome, Edge, Brave, and Opera (Manifest V3) plus Firefox (Manifest V2). Install from the Chrome Web Store or Firefox Add-ons — both are linked in the install section above.
How many themes does JpyLens include?
13 carefully crafted themes covering both light and dark palettes — GitHub, Dracula, One Dark Pro, Tokyo Night, Ayu, Nord, Solarized (Light/Dark), Monokai Pro, One Monokai, Rosé Pine, Shades of Purple, and Winter Is Coming. Try them live in the Themes section above.
Is JpyLens free? Is the source code open?
Yes to both. JpyLens is free, with no ads, no upsells, and no premium tier. The full source is open on GitHub — pull requests welcome.
Install JpyLens.
Open .ipynb. Read.
Pick the package for your browser. All builds are pre-signed and ready to go.