SubstackDownloader

Save Substack posts in formats you can read anytime.

SubstackDownloader helps writers, researchers, and readers keep their subscribed articles easy to access, so they can read whenever they want.

Why SubstackDownloader

• Export a single article as a .md file
• Export entire publications as a ZIP of Markdown files
• Export directly to a local folder (Chrome/Edge) for easier long reading lists
• Keep readable formatting and metadata
• Works with paywalled content you are authorized to access (via your session cookie: substack.sid on *.substack.com, or connect.sid on custom domains)
• Optional browser capture for posts that only fully render after Substack's app hydrates
• Fast, simple UI with no signup and no database required

How It Works

Single Article

1. Paste a Substack article URL.
2. Click convert.
3. Download Markdown instantly.

All Articles (Bulk Export)

1. Paste a Substack publication URL.
2. Add your session cookie (see below).
3. Click Step 1: Load all articles.
4. Select posts and use Step 2 export actions.
5. Prefer Export Markdown to folder (Chrome/Edge) for large archives; use ZIP as fallback.

Session cookies

Substack uses different cookie names depending on the site:

Site	Cookie name	Where to find it
*.substack.com (e.g. author.substack.com)	substack.sid	Cookies for https://substack.com or your publication host
Custom domain (e.g. lennysnewsletter.com)	connect.sid	Cookies for that exact domain

1. Sign in to the publication in your browser.
2. Open DevTools (Ctrl+Shift+I) → Application → Cookies → select the site you’re using.
3. Copy the value of substack.sid or connect.sid (whichever exists for that site).
4. Paste it into Connect Substack in SubstackDownloader.

Run Locally

npm install
npx playwright install chromium
npm run dev

Open http://localhost:3000.

Useful Commands

npm run build
npm run lint
npm test

Deploy

Deploy on Vercel by importing this repository.

• No environment variables required
• Bulk export route uses maxDuration = 300
• Browser capture needs Playwright Chromium available on the host
• For large exports, run locally when possible (hosted/serverless ZIP jobs may time out)

For Developers

• Built with Next.js 14 (App Router) + React 18
• Conversion powered by cheerio and turndown
• Optional browser capture powered by Playwright
• Bulk ZIP generation via archiver
• Unit tests with Jest

Responsible Use

• SubstackDownloader is not affiliated with Substack.
• Export only content you are legally and ethically authorized to access.