What you get#
Onekey exposes Substack as 8 endpoints behind one API key: 2 endpoints return one record (data is an object) and 6 endpoints return a list (data is an array). Every answer uses the same envelope (success, data, metadata, error), the cost is reported in metadata.credits_charged, and fields are mapped onto the unified schema so the code you write for Substack also works for the rest of the news & publishing category.
Endpoints#
| Endpoint | What it does | Parameters | Credits | Status |
|---|---|---|---|---|
archive | Latest posts of a Substack publication. | pub* | 5 | stable |
categories | Substack's publication categories. | - | 5 | stable |
category_publications | Top publications in a Substack category. | id* | 5 | stable |
post | Fetch a Substack post by slug. | pub*, slug* | 1 | stable |
post_comments | Comments on a Substack post (by post id). | pub*, id* | 5 | stable |
search | Search posts within a Substack publication. | pub*, q* | 5 | stable |
top_posts | Top posts of a Substack publication. | pub* | 5 | stable |
user | Fetch a Substack user's public profile by handle. | handle* | 1 | stable |
A * marks a required parameter. Each endpoint name links to its reference page with the full parameter table, caching window and a recorded response.
Make a request#
This calls substack.post (1 credit, stable). Replace YOUR_API_KEY with your key; sign up, no card. 1,000 free credits cover the open-platform endpoints. Hard-to-reach platforms (X, TikTok, Instagram, Reddit, and others marked on their page) need a verified email and a purchased pack.
curl "https://api.onekey.dev/v1/substack/post?pub=www.astralcodexten.com&slug=open-thread-435" \
-H "x-api-key: YOUR_API_KEY"Fields you get back#
These unified fields come back from Substack, with the same names as on every other platform. The count is how many of its 8 mapped endpoints return the field; a field the source lacks is null, never missing. 3 platform-specific fields (ext.<name>) come on top, documented on each endpoint page.
| Field | Type | Endpoints |
|---|---|---|
author.id | string | 7 |
content.createdAt | ISO 8601 date | 7 |
author.avatarUrl | URL | 6 |
author.displayName | string | 6 |
content.text | string | 6 |
entity.slug | string | 6 |
author.username | string | 5 |
content.id | string | 5 |
engagement.likes | integer | 5 |
media.thumbnailUrl | URL | 5 |
content.title | string | 4 |
content.url | URL | 4 |
engagement.comments | integer | 4 |
entity.id | string | 2 |
entity.name | string | 2 |
entity.description | string | 1 |
The full schema is in Unified schema.
Pricing#
Substack calls cost 1 to 5 credits, flat per endpoint. Free when served from cache (0.2 credit for a cached response over 100 KB). Invalid, failed or not-found calls are not charged. See pricing for credit packs.