Read any Substack publication as a local, full-text-searchable corpus — keyless for free posts, your own session for what you subscribe to.
Substack Reader archives whole publications into a local SQLite mirror you can search, SQL-query, and read offline. Free posts need no login; paid posts you're entitled to unlock with your own session cookie — never redistributed, always opt-in. Unlike every other Substack tool it builds a corpus that compounds instead of fetching live per call.
Authentication
Free/public posts are keyless — zero setup. To read paid posts you already subscribe to, provide your own Substack session cookie (substack.sid); this reads only what you are already entitled to and is never required for free content.
Quick Start
# confirm reachability and config before anything else
substack-reader-pp-cli doctor --dry-run
# mirror a publication's recent posts into the local corpus
substack-reader-pp-cli archive astralcodexten --limit 50
# full-text search the corpus offline
substack-reader-pp-cli search "open thread"
# read a single post's full text
substack-reader-pp-cli read astralcodexten/open-thread-441
Unique Features
These capabilities aren't available in any other tool for this API.
Local corpus that compounds
-
archive — Archive a whole Substack publication into a local SQLite mirror you can read, search, and query offline — no other Substack tool builds a persistent corpus.
Reach for this to turn a live newsletter into a durable, queryable knowledge base instead of re-fetching every time.
substack-reader-pp-cli archive astralcodexten --limit 200
-
sql — Run read-only SQL over your local Substack corpus for arbitrary analytics — post cadence, audience mix, longest posts — from data you've already archived.
Reach for this for ad-hoc analytics over what you've archived, without re-fetching or writing code.
substack-reader-pp-cli sql "SELECT audience, count(*) FROM posts GROUP BY audience"
Entitlement-aware reading
-
read — Read a post's full text; free posts keyless, and paid posts you subscribe to via your own session cookie — with an honest 'preview only, you're not entitled' signal.
Use to pull a specific post's full text into an agent workflow, respecting exactly what the user is entitled to.
substack-reader-pp-cli read astralcodexten/open-thread-441
Topic & comparative intelligence
-
digest — A time-windowed digest across every publication in your local corpus — what's new since you last synced, ranked, in one view.
Use as a personal 'what did I miss across my newsletters' briefing.
substack-reader-pp-cli digest --since 7d
-
author-compare — Compare two publications' cadence, topics, and free/paid mix from the local corpus.
Use to size up a newsletter before subscribing, or to study what a successful author publishes.
substack-reader-pp-cli author-compare astralcodexten blog.bytebytego.com
Recipes
Build a searchable corpus
substack-reader-pp-cli archive astralcodexten --limit 200 && substack-reader-pp-cli search "prediction markets"
Mirror a publication then search it offline with FTS ranking.
Narrow a large post to fields
substack-reader-pp-cli read astralcodexten/open-thread-441 --agent --select title,post_date,audience,body_html
Pull only the fields an agent needs from a verbose post object.
Audience mix analytics
substack-reader-pp-cli sql "SELECT audience, count(*) FROM posts GROUP BY audience"
Read-only SQL over the local corpus for arbitrary analytics.
Usage
Run substack-reader-pp-cli --help for the full command reference and flag list.
Paths & environment variables
This CLI separates local files into four path kinds:
| Kind | Contents |
|---|
config | User-editable settings such as config.toml and saved profiles |
data | Durable local data such as data.db |
state | Runtime state such as persisted queries, jobs, and teach.log |
cache | Regenerable HTTP/cache files |
Each kind resolves independently. The ladder is:
- Per-kind env var:
SUBSTACK_READER_CONFIG_DIR, SUBSTACK_READER_DATA_DIR, SUBSTACK_READER_STATE_DIR, or SUBSTACK_READER_CACHE_DIR
--home <dir> for this invocationSUBSTACK_READER_HOME for a flat relocated root- XDG env vars:
XDG_CONFIG_HOME, XDG_DATA_HOME, XDG_STATE_HOME, XDG_CACHE_HOME
- Platform defaults matching existing installs
For containers and agent sandboxes, prefer a single relocated root:
export SUBSTACK_READER_HOME=/srv/substack-reader
substack-reader-pp-cli doctor
Under SUBSTACK_READER_HOME=/srv/substack-reader, the four dirs resolve to /srv/substack-reader/config, /srv/substack-reader/data, /srv/substack-reader/state, and /srv/substack-reader/cache.
MCP servers do not receive CLI flags from the host. Put relocation in the host env block:
{
"mcpServers": {
"substack-reader": {
"command": "substack-reader-pp-mcp",
"env": {
"SUBSTACK_READER_HOME": "/srv/substack-reader"
}
}
}
}
Precedence matters in fleets: an ambient per-kind variable such as SUBSTACK_READER_DATA_DIR overrides an explicit --home for that kind. Use SUBSTACK_READER_HOME or the per-kind variables for durable fleet relocation; treat --home as the weaker per-invocation lever.
Relocation is one-way. Unsetting SUBSTACK_READER_HOME does not move files back to platform defaults, and doctor cannot find files left under a former root. Move the files manually before unsetting relocation variables.
Existing installs keep working because the platform-default rung matches the legacy layout. Run substack-reader-pp-cli doctor --fail-on warn to check path warnings in automation.
Commands
categories
Browse Substack's publication categories
substack-reader-pp-cli categories browse - List publications in a categorysubstack-reader-pp-cli categories list - List all Substack categories
publications
Discover Substack publications
substack-reader-pp-cli publications <query> - Search Substack publications by name (best-effort; may return few results anonymously)
Self-learning loop
This CLI caches per-question discovery so repeat queries skip the walk and structurally similar queries get answered via entity substitution. The loop also self-captures: every invocation is journaled locally, and failed-flag corrections plus fresh teaches surface as candidates on the next recall for confirm/reject judgment. Agents call recall before discovery and fire teach & after answering. See the ## Automatic learning section in SKILL.md for the full protocol.
substack-reader-pp-cli recall <query> - Look up cached resources for a query before running discoverysubstack-reader-pp-cli teach - Record a query -> resource mapping (silent on success, safe to background with &)substack-reader-pp-cli learnings list - Inspect taught rowssubstack-reader-pp-cli learnings forget <query> - Undo a teachsubstack-reader-pp-cli learnings candidates - List auto-captured candidates awaiting confirm/rejectsubstack-reader-pp-cli learnings stats - Local loop metrics: recall hit rate, teach-to-reuse, playbook resolution, candidate countssubstack-reader-pp-cli teach-pattern - Install a query/resource template up frontsubstack-reader-pp-cli teach-lookup - Add an entity mapping (e.g. country code, team alias) for pattern substitution
Pass --no-learn or set SUBSTACK_READER_NO_LEARN=true to disable the loop for deterministic flows.
The local store's schema version stamp is one-way: once this version of substack-reader-pp-cli opens the database, older binaries refuse it with a version error — upgrade the binary rather than downgrading.
Output Formats
# Human-readable table (default in terminal, JSON when piped)
substack-reader-pp-cli categories list
# JSON for scripting and agents
substack-reader-pp-cli categories list --json
# Filter to specific fields
substack-reader-pp-cli categories list --json --select id,name,status
# Dry run — show the request without sending
substack-reader-pp-cli categories list --dry-run
# Agent mode — JSON + compact + no prompts in one flag
substack-reader-pp-cli categories list --agent
Agent Usage
This CLI is designed for AI agent consumption:
- Non-interactive - never prompts, every input is a flag
- Pipeable -
--json output to stdout, errors to stderr
- Filterable -
--select id,name returns only fields you need
- Previewable -
--dry-run shows the request without sending
- Read-only by default - this CLI does not create, update, delete, publish, send, or mutate remote resources
- Offline-friendly - sync/search commands can use the local SQLite store when available
- Agent-safe by default - no colors or formatting unless
--human-friendly is set
Exit codes: 0 success, 2 usage error, 3 not found, 5 API error, 7 rate limited, 10 config error.
Health Check
substack-reader-pp-cli doctor
Verifies configuration and connectivity to the API.
Configuration
Run substack-reader-pp-cli doctor to see the resolved config, data, state, and cache directories. The platform-default config path is ~/.config/substack-reader-pp-cli/config.toml; --home, SUBSTACK_READER_HOME, and per-kind env vars can relocate it.
Static request headers can be configured under headers; per-command header overrides take precedence.
Troubleshooting
Not found errors (exit code 3)
- Check the resource ID is correct
- Run the
list command to see available items
API-specific
- A paid post reads as preview-only despite being subscribed — Check that your substack.sid session cookie is set (SUBSTACK_SESSION or the config cookie file) and current — an expired or mistyped cookie silently falls back to the public preview. The reader unlocks paid posts through Substack's authenticated by-id endpoint, so a valid session is all that is needed; you never target a particular host yourself.
- Empty results / HTTP 429 — You are being rate-limited; slow down (archive is self-throttled) — Substack sets no rate headers, so pace requests.
Sources & Inspiration
This CLI was built by studying these projects and resources:
Generated by CLI Printing Press