substack API

Substack API For Publishing, Scheduling, And Automation

Ian Kiprono, Founder of NarrareachUpdated July 16, 2026

Narrareach provides a Substack publishing workflow for scheduling Notes and articles, managing drafts and images, distributing content to supported channels, and reacting to publish events. This is separate from Substack's official Developer API, which currently retrieves public profile information by a creator's linked LinkedIn handle rather than publishing posts.

At a glance

Substack API publishing workflow

Narrareach gives writers, developers, and content teams a reviewed publishing workflow for Substack Notes and articles, cross-platform distribution, queue state, webhooks, and AI-agent actions.

Read the API docs Open API setup

Substack Notes and article scheduling: so Substack content can move from draft to scheduled queue without manual posting
Cross-platform distribution: so the same idea can travel to Medium, LinkedIn, X, Bluesky, and Threads from the same workflow
Webhook event delivery: so your own tools can react when a post publishes, fails, or needs attention
Performance and subscriber signals: so you can see which posts deserve follow-up distribution

What this page covers

What does the official Substack API support?How Narrareach handles Substack publishing workflowsPublishing API requirements beyond the POST requestSubstack API use cases for writers, teams, and AI agents

Review the Narrareach API, MCP, and webhook surfaces before choosing the integration path.

The problem

The manual version gets old fast.

The phrase Substack API now refers to several different things. Substack has an official Developer API, but its currently documented endpoint is designed to retrieve public profile information for verified creators linked to LinkedIn. It is not documented as a general API for publishing Notes or articles.

Developers who need publishing automation therefore face a different operational problem: authenticated account access, drafts, images, scheduling, retries, queue state, platform changes, failure recovery, and visibility for the writer who owns the content.

Narrareach provides that operating layer through its product, API, MCP, and webhook surfaces. External tools can hand work to a reviewed publishing queue instead of treating a changing platform request as the whole system.

What does the official Substack API support?

Substack introduced an official Developer API in 2026. Its published documentation describes an authenticated profile-search endpoint that accepts a public LinkedIn handle and returns matching public Substack creator profile data.

Access requires a Substack account, agreement to the API Terms of Use, approval, and a token generated from Substack settings. The documented endpoint is useful for creator identity and profile discovery. It should not be described as an official Notes or article publishing endpoint unless Substack expands the documentation.

That scope matters because a searcher asking for the Substack API may want profile data, publishing automation, analytics, subscriber management, or an integration with an AI assistant. A useful guide identifies the actual job before recommending a technical path.

Use the official Developer API when its documented profile-search response matches the product requirement.
Do not present undocumented publishing endpoints as capabilities of the official Developer API.
Review Substack's terms and current documentation before building a production dependency.

How Narrareach handles Substack publishing workflows

Narrareach connects the writer's Substack account to a publishing system built around drafts, scheduled Notes, long-form articles, images, platform-specific versions, and delivery state. A writer can use the dashboard directly while an internal tool, script, or AI assistant works through Narrareach's authenticated interfaces.

A publishing request becomes a visible queue item rather than a hidden background call. The writer can review the content and timing, see whether it is scheduled or published, and respond when a connection or destination needs attention.

The same source idea can also produce reviewed versions for Medium, LinkedIn, X, Bluesky, Threads, and other supported channels. Narrareach keeps those versions connected without implying that every destination accepts the same fields or format.

Start with a draft or one scheduled item before enabling higher-volume automation.
Keep a human review step for AI-generated or externally supplied content.
Store the Narrareach item identifier so the source system can reconcile later status changes.

Publishing API requirements beyond the POST request

Reliable scheduling requires more than content and a timestamp. The system needs an authenticated destination, timezone handling, media validation, platform-specific fields, idempotent retries, state transitions, and a clear result when the destination accepts, rejects, or delays the publish action.

Narrareach keeps those concerns inside the publishing workflow. API-created and agent-created work enters the same operational system as dashboard-created work, which reduces the risk of two queues disagreeing about what should publish next.

Webhooks let a downstream system react to supported publishing events instead of continuously polling. The receiving application should still authenticate webhook requests, handle duplicate delivery safely, and preserve enough context to investigate a failed job.

Use stable source identifiers and idempotency controls when retrying a create or schedule operation.
Validate image URLs, destination-specific limits, and publish time before the job enters the queue.
Treat a queued response as acceptance into the workflow, not proof that the destination has already published it.

Substack API use cases for writers, teams, and AI agents

A solo writer can import a prepared batch of Notes, schedule a week of publishing, and keep the queue visible without writing integration code. A content team can move approved article drafts from an internal calendar into Narrareach while editors retain control over publication and follow-up distribution.

A developer can use Narrareach as the last-mile publishing layer behind a CMS, research tool, or content application. An MCP-capable assistant can inspect supported publishing context, prepare drafts, and queue reviewed actions without storing every destination credential inside the assistant configuration.

The strongest use case is a closed loop: create or import the source, publish it through a controlled queue, collect the available performance and subscriber signals, and use those results to choose the next article or Note rather than automating output with no feedback.

Match the integration surface to the job: dashboard for direct operation, REST API for application workflows, MCP for assistants, and webhooks for event-driven updates.
Give agents the least privilege required and rotate exposed tokens immediately.
Keep editorial approval and source traceability even when draft creation is automated.

Sources and methodology

Definitions grounded in current platform documentation

Substack Developer APISubstack's current access requirements, authentication instructions, profile-search endpoint, and response definition.Narrareach API documentationCurrent Narrareach REST API, MCP, authentication, publishing workflow, and webhook documentation.

How Narrareach solves it

Keep the publishing system close to the writing.

Substack Notes and article scheduling - so Substack content can move from draft to scheduled queue without manual posting

Cross-platform distribution - so the same idea can travel to Medium, LinkedIn, X, Bluesky, and Threads from the same workflow

Webhook event delivery - so your own tools can react when a post publishes, fails, or needs attention

Performance and subscriber signals - so you can see which posts deserve follow-up distribution

Substack API options solve different jobs

Choose the official API, a maintained publishing workflow, or a custom client based on the action and operational responsibility you actually need.

Capability	Official Substack Developer API	Custom or unofficial client	Narrareach workflow
Public creator profile lookup	Documented by Substack	Possible to wrap	Not the primary use case
Notes and article publishing	Not in current public documentation	Requires ongoing maintenance	Supported through Narrareach publishing paths
Scheduling and visible queue state	Not the documented purpose	You build it	Included in the product workflow
Retries and failure recovery	Application responsibility	You build it	Handled inside the Narrareach workflow
Cross-platform distribution	Not the documented purpose	Separate integrations required	Connected supported destinations share one workflow
Writer review and dashboard	Not the documented purpose	You build it	Included

Substack can change its official API scope. Check the current Developer API documentation before implementation.

Start here

Build on a Substack-first publishing workflow

Review the Narrareach API, MCP, and webhook surfaces before choosing the integration path.

Read the API docs

Questions writers ask

Does Substack have an official API?

Yes. Substack published a Developer API in 2026. Its current public documentation describes a profile-search endpoint that retrieves public creator information from a linked LinkedIn handle. It is not documented as a general Notes or article publishing API.

Can the official Substack API publish Notes and articles?

The current official Developer API documentation does not describe Notes or article publishing endpoints. Use the documented API for its stated profile-search purpose and treat publishing automation as a separate integration requirement.

Does Narrareach support Substack publishing workflows?

Yes. Narrareach supports authenticated workflows for drafts, scheduled Substack Notes and articles, queue state, distribution, webhooks, and performance review. This is a Narrareach workflow, not a claim that Substack's official Developer API exposes the same publishing operations.

Do my scripts need to store Substack credentials?

Connect the destination account inside Narrareach and use Narrareach tokens for the external integration. Keep every token private, scope access to the required workflow, and rotate any credential that may have been exposed.

Can an API-created Substack post remain a draft?

Narrareach supports reviewed article and Notes workflows where content can be prepared before publication. The exact draft, schedule, or immediate-publish options depend on the content type and selected Narrareach endpoint.

Can Substack publishing workflows include images and metadata?

Narrareach publishing workflows can carry the supported content, images, tags, and article metadata required by the selected path. Destination-specific fields are validated and only supported metadata is sent to each platform.

Can Substack API workflows cross-post to social platforms?

Narrareach can create reviewed destination-specific versions for connected platforms such as Medium, LinkedIn, X, Bluesky, and Threads. Each platform remains subject to its own connection, limits, supported fields, and current availability.

How do I know whether an API-created post published?

Read the Narrareach item state or subscribe to supported webhook events. A successful queue response means the job entered the workflow; the final published state and destination URL should be confirmed separately.

Narrareach LLM connector

Connect Claude, ChatGPT, or any MCP-compatible agent to read drafts, schedule posts, and automate Substack, Medium, LinkedIn, X, Bluesky, and Threads workflows.

Read the docs