SubstackAPI

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An unofficial, open-source API for accessing and displaying Substack content in external applications. It combines Substack’s unofficial API and RSS feeds for reliability and performance.

📌 Official Website: substackapi.dev – Find the latest guides, documentation, and updates.

Features

• Fast and reliable access to publication content
• Simple authentication using API keys
• Redis-powered caching for optimal performance
• Generous rate limits
• Free to use

Getting Started

1. Generate an API Key

Visit auth.substackapi.dev to create your API key. You'll need your Substack publication URL.

2. Try the API

You can try out all endpoints and see detailed documentation at substackapi.dev/endpoints.

3. Make API Requests

Include your API key in the X-API-Key header when making requests:

curl https://api.substackapi.dev/posts/latest?publication_url=example.substack.com \
-H "X-API-Key: your_api_key_here"

Available Endpoints

• /posts/latest - Get the latest posts
• /posts/top - Get the most popular posts
• /posts/search - Search for posts
• /post - Get a single post by slug

Usage Guidelines

• This API is intended for content owners accessing their own Substack publication data
• Each API key is limited to accessing a single publication
• Rate limits apply per endpoint (see Usage Limits)
• Test API key available: sk_test_9b0j6a1bdbf4f38b1

Technical Overview

The API implements a simple hybrid approach combining:

1. Substack's unofficial API (primary data source)
2. RSS Feed (fallback mechanism)
3. Redis caching layer

flowchart LR
Client[API Client]
Cache[(Redis Cache)]
API[Unofficial API]
RSS[RSS Feed]
Client --> Cache
Cache -- "Cache Miss" --> API
API -- "Error" --> RSS
API --> Cache
RSS --> Cache
Cache --> Client

This architecture ensures:

• Reliable and unlimited access to publication data
• Minimal dependency on unofficial APIs
• Fast response times
• High availability through fallback mechanisms

For more technical details, visit Technical Overview.

Author

Created and maintained by Noah Bjorner

• 📧 Email: bjornernoah@gmail.com
• 🛠 GitHub: @Noah-Bjorner

License

This project is licensed under the MIT License - see the LICENSE file for details.