Sci-Hub PDF Downloader — Chrome Extension

A Chrome extension that detects DOIs on journal/paper pages and downloads PDFs directly from Sci-Hub. No copy-pasting DOIs, no navigating to Sci-Hub manually. Just click the button.

How it works

1. When you visit a journal article page (Nature, Science, IEEE, Elsevier, Springer, etc.), the extension detects the DOI from meta tags, the URL, JSON-LD data, or visible text
2. A floating Sci-Hub PDF button appears in the bottom-right corner
3. Click it and the extension fetches the paper from Sci-Hub in the background — the PDF downloads directly to your Downloads folder
4. If one Sci-Hub mirror fails, it automatically tries the next one

The extension does NOT open a new tab or redirect you. The PDF downloads silently while you stay on the page.

Supported DOI sources

The extension finds DOIs from (in priority order):

Source	Example
<meta> tags	<meta name="citation_doi" content="10.1038/nature12373">
URL patterns	https://doi.org/10.1038/nature12373
JSON-LD	Schema.org structured data
Page text	DOI visible in article headers/metadata

Works on virtually every academic publisher: Nature, Science, Cell, PNAS, IEEE, Elsevier, Springer, Wiley, ACS, Taylor & Francis, SAGE, Oxford, Cambridge, PubMed, and more.

Install

This extension cannot be published to the Chrome Web Store. Install it as an unpacked extension:

1. Clone or download this repo

git clone https://github.com/esaruoho/scihubpy-extension.git

Or download as ZIP and extract.

2. Load in Chrome

1. Open Chrome and go to chrome://extensions/
2. Enable Developer mode (toggle in the top-right corner)
3. Click Load unpacked
4. Select the scihubpy-extension folder (the one containing manifest.json)
5. The extension icon appears in your toolbar

3. Use it

Navigate to any journal article page. If a DOI is detected, a Sci-Hub PDF button appears in the bottom-right corner. Click it. Done.

Mirrors

The extension tries these Sci-Hub mirrors in order:

Mirror	Method
sci-hub.vg	<iframe> with sci.bban.top CDN
sci-hub.al	<embed> with sci.bban.top CDN
sci-hub.mk	<embed> with sci.bban.top CDN
sci-hub.ru	<object> with self-hosted /storage/

If mirrors change, edit the SCIHUB_MIRRORS array in background.js.

Files

manifest.json    — Chrome extension manifest (Manifest V3)
content.js       — DOI detection + button injection (runs on every page)
background.js    — Sci-Hub fetch + PDF parsing + download (service worker)
styles.css       — Button styling
icons/           — Extension icons

How the PDF parsing works

The background service worker replicates the same logic as scihub.py:

1. Fetch https://sci-hub.vg/{DOI}
2. Parse the HTML response for the PDF URL in this order:
   • <iframe src="..."> (classic Sci-Hub)
   • <embed type="application/pdf" src="..."> (newer mirrors)
   • <object data="..."> (sci-hub.ru)
   • <button onclick="location.href='...pdf'"> (download buttons)
   • Script tags with PDF URLs
3. Fetch the actual PDF binary
4. Validate PDF magic bytes (%PDF-)
5. Trigger chrome.downloads to save the file

Permissions

Permission	Why
activeTab	Read the current page to detect DOIs
downloads	Save PDFs to disk
host_permissions for sci-hub.*	Fetch Sci-Hub pages and PDFs from the background

Notes

• Sci-Hub has not added new papers since 2021. Papers published after 2021 may not be available.
• CAPTCHAs may appear after many consecutive downloads. The extension handles this by rotating mirrors.
• This extension is for personal/educational use.

Related

• scihub.py — Python CLI tool with the same Sci-Hub fetching logic

License

MIT