Free tools Windows power users keep installed
One-click scans. No signup required.
Not through a documented, universal Substack API. Substack documents importing an existing archive from supported platforms or some RSS feeds, but that is a migration workflow—not a confirmed service that keeps every external blog in sync. For future posts, you can publish in Substack’s editor or consider a third-party tool, after checking exactly what it supports and how it handles account access.
Importing an archive is different from syncing new posts
Substack’s documented importer is designed to bring existing posts into a publication. To use it, sign in and open Settings > Import/Export > Import posts. Enter the source blog or newsletter URL, or an RSS feed where supported, review the posts Substack finds, and choose Import. Some platforms may require a file upload instead. Substack says imported posts appear in the publication archive; they may need cleanup after import. The steps and platform-specific options are in Substack’s import guide.
As an Amazon Associate I earn from qualifying purchases.
The import guide also describes an option to update existing posts when re-importing. That is not the same as ongoing monitoring: Substack’s published instructions do not say that the importer watches an external blog and automatically republishes future posts.
RSS imports can miss older posts
Substack says its importer accepts RSS feeds from some sources, including Squarespace and ConvertKit. RSS is only as complete as the feed the source provides. Substack’s migration overview warns that some feeds expose only recent entries—for example, the latest 20 posts. Before importing, compare the posts available in the feed with the history you intend to migrate. See the import guide and Substack’s migration overview.
#1 Best Overall
Does Substack have an API for publishing posts?
Substack’s Developer API Terms describe access to information that creators make public on their profiles or publications, with examples including a creator’s name, publication URL, subscriber count, and profile summary. The terms allow uses such as displaying public information and supporting discovery, analytics, or integrations involving public profiles and publications. They also note that access is subject to rate limits and technical restrictions.
Those terms do not document a general public endpoint for sending every new post from any external blog to a Substack publication. The terms were last updated January 8, 2026; read them at Substack Developer API Terms. The existence of API terms should not be taken as confirmation of an official, general-purpose publishing API.
Rank #2
What are the options for publishing future posts?
Publish in Substack’s editor
For a new post, Substack documents a dashboard workflow: choose Create > Article, prepare the post, and select its audience, comment access, tags, email or app delivery, and scheduling options. This is a Substack publishing flow; it does not itself synchronize a post from another blog. The available controls are described in Substack’s publishing guide.
Evaluate a third-party sync or publishing service
ApiSubstack advertises a blog-sync and publishing product, including the claim “Sync any blog to Substack in one-click.” Its setup material describes authentication using a Substack session cookie. This is a third-party vendor’s representation, not a Substack-endorsed integration or independent proof of broad platform coverage, reliable continuous syncing, or security quality. See ApiSubstack.
Before connecting an account, get clear answers from the provider about:
- Which specific blog platforms and content formats it supports, and whether it imports an archive, detects future posts, or only provides a publishing interface.
- Whether you can preview posts, control duplicates and updates, and prevent a post from being emailed or sent to the app unintentionally.
- What access the session cookie grants, how the service stores and protects it, how to revoke access, and what happens if authentication expires.
- How failures are reported and retried, what support is available, and how to avoid duplicate posts during recovery.
Substack’s documentation does not settle these vendor-specific questions, and the product’s own claims are not an independent security or reliability assessment.
Rank #4
Which route fits your goal?
| Route | What it is documented to do | Key limit |
|---|---|---|
| Substack archive import | Imports existing posts from listed platforms by URL, or from some other sources through RSS; some sources may require file uploads. | A migration workflow, not documented ongoing synchronization. RSS may contain only recent posts. |
| Substack editor | Creates and publishes an article from the dashboard, with controls for audience, comments, tags, delivery, and scheduling. | It is a publishing workflow, not an automatic bridge from an external blog. |
| Third-party service | ApiSubstack advertises blog syncing and publishing tools and describes session-cookie authentication. | Coverage, ongoing behavior, credential handling, support, and Substack endorsement are not independently established by the vendor’s site alone. |
Don’t confuse podcast feeds with blog-post synchronization
Substack documents an automatic workflow for distributing external podcast episodes through a podcast RSS feed. That feature is specific to podcast episodes; it does not establish automatic syncing for ordinary blog articles. The podcast workflow is described in Substack’s podcast RSS guide.
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesLikewise, each Substack publication has an outbound feed at https://your.substack.com/feed. That can help distribute Substack posts elsewhere, but it is not evidence of an inbound feed that continuously copies an external blog into Substack. Details are in Substack’s RSS-feed guide.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
