Substack API Reference — Development skill for Claude Code
Unofficial Substack API reference — 129 verified endpoints with body shapes, gathered across 14 capture rounds.
How to install Substack API Reference
This entry records only its repository, not the path inside it, so there is no
exact command to give. Open AnthonyDavidAdams/substack-api-reference and copy the folder into
~/.claude/skills/, or the file into ~/.claude/agents/.
What Substack API Reference does
Unofficial Substack API reference — 129 verified endpoints with body shapes, gathered across 14 capture rounds. Read + write side fully mapped. Includes Claude Agent SDK skill manifest and TypeScript client.
Alternatives in Development
- Theme Color Conventions — Extensions in this repo use a consistent color language mapped to Pi's theme tokens 526 ★
- Check Setup.En — Top-level alias — see lesson/check-setup.en.md for the full body 347 ★
- HERO Anti OverDefense — HERO = Hashing · Edge cases · Rubrics · Overbuild — the four shapes coding agents over-defend in 333 ★
README
Substack API Reference (Unofficial)
The most complete map of Substack's undocumented internal API. **129 verified endpoints**, captured by driving the live API through 14 rounds of probing and write-side capture.
[](LICENSE)   
A practical, verified reference for Substack's undocumented internal API. Every endpoint here has been tested against the live API. Designed for humans **and** for AI agents (see [`SKILL.md`](SKILL.md)).
⚠️ **Unofficial.** Substack doesn't publish or support this API. Endpoints can change without notice. Treat this as a working notebook, not a contract.
Why this exists
The Substack web app speaks to a JSON API at `https://substack.com/api/v1/*` and per-publication subdomains at `https://.substack.com/api/v1/*`. The web app uses it for everything: reading posts, creating drafts, publishing, managing subscribers, sending chat threads, configuring recommendations. With a session cookie, you can drive the same API from any script.
Existing community work covers parts of this surface:
- NHagar/substack_api — Python, read-focused
- ma2za/python-substack — Python, full CRUD
- jakub-k-slys/substack-api — TypeScript (archived)
- JPres-Projects/Substack-API — Python, draft + publish
This repo is intended to be **the canonical endpoint reference** these clients converge on. Submit a PR with anything new you find.
Quick start
# 1. Get your session cookie (see AUTH.md for browser-extension and DevTools paths)
COOKIE='s%3A...your.connect.sid.value...'
# 2. Verify iRelated Skills
Agentrouter
Unofficial SDK for AgentRouter (agentrouter.org) — Claude, DeepSeek, and GLM via OpenAI-compatible proxy. Zero
Gemini Substack Generation
MASTER PROMPT: Substack Content Generation
Continue Triage
Continue dialog with the user on an open issue. Ask a follow-up question OR hand off to maintainer when enough
Keyword Cluster
Cluster a list of keywords into topical groups mapped to content pages. Paste or provide keywords and get orga
Live Provider Debugging
Diagnose provider compatibility issues such as invalid message shapes, reasoning-content mismatches, and long-
Architecture Drawer
Skill for Claude Code & Codex: describe your system architecture in text → get an editable PowerPoint diagram
Related Agents
Stack Detector
Deep project stack discovery that scans all config files, source code, and infrastructure to produce a compreh
Figma Implementer
Turn a Figma design file into a build-ready specification — design variables mapped to Tailwind tokens, per-se
Source Acquisition
Run all search rounds, citation chasing, triage, and downloads for a deep research session. Returns a compact
