Substack on your own domain.

Unlike Twitter, Instagram, or LinkedIn, Substack has not shipped a public API. There is no developer portal, no OAuth flow, and no documented endpoint catalogue. What Substack does expose, by design, is a per-publication RSS feed at /feed (for example, yourname.substack.com/feed). The feed includes the post title, publish date, full HTML body for free posts, a public preview for paid posts, podcast episode enclosures with audio file URLs, cover image URLs, and author metadata. Every legitimate Substack widget on the market is built on top of this RSS feed, because it is the only stable, terms-of-service-friendly access point. Poper reads your RSS feed continuously, caches it on a global CDN edge, and re-renders it with the styling you choose. No scraping, no headless browser, no fragile workarounds. The RSS feed is your source of truth, and your widget always reflects it.

Substack's paid subscription tier is the platform's killer feature. Roughly 1 in 14 active subscribers across Substack pays for at least one publication, and the platform processes billions of dollars per year through its Stripe-based billing system. When you publish a paid post, Substack includes a public preview in the RSS feed (typically the first paragraph or two) followed by a paywall marker. A well-built widget renders that preview honestly, then surfaces a Subscribe to read the rest CTA wired straight to your Substack paid tier signup. Poper handles paid post teasers exactly this way: the preview is shown with a clear paywall badge, the CTA button uses your Substack URL with source attribution, and your paid tier conversion funnel runs from your own domain. The Subscribe button never ships readers into a Substack-branded iframe, and the widget does not break Substack's terms by attempting to render gated content.

In April 2023, Substack launched Notes, a microposting feature that looks and feels a lot like Twitter or Threads, embedded directly inside the Substack reader. Notes is the platform's bet that the post-Twitter migration of writers, journalists, and founders needed a short-form home that lived inside their existing newsletter relationship. As of 2026, Notes is one of the highest-engagement surfaces on Substack: founder-led publications use it for build-in-public threads, journalists use it for live-tweet style coverage, and writers use it to surface drafts and reading recommendations. Notes are exposed alongside the main RSS feed for most publications, which means a good widget can surface them on your site as a ticker, sidebar, or hero strip. Poper renders Notes as a separate feed type, so you can show your latest 3 Notes above your most recent long-form post, or run a dedicated Notes-only block in your sidebar.

Substack takes a flat 10% of paid subscription revenue plus Stripe fees. There is no monthly platform fee. The economics work for writers below roughly 5,000 paid subscribers, where the cut is cheaper than the fixed cost of a Beehiiv Pro or Ghost Pro plan, and Substack's growth tools (Recommendations, Notes, the iOS app reader) actively help free subscribers find you. Beehiiv charges a flat monthly fee tied to subscriber count, takes 0% of revenue, and is the favourite of large operators and growth-focused newsletter publishers. Ghost is open-source self-hosted (or hosted via Ghost Pro), takes 0%, and is the favourite of brand publishers and tech-savvy operators who want full design control. Independent writers and founder-led newsletters tend to choose Substack for the discovery network and the all-in-one billing. They then use a tool like Poper to embed the Substack feed on their own author or publication site, getting the best of both worlds: Substack's relationship with the reader and Substack's billing, plus their own brand, discovery, and SEO on their own domain. This guide is mostly for that audience.

Between 2022 and 2026, the open web watched a wave of writers, journalists, and operators leave centralised social platforms and stake out a paid newsletter as the centre of gravity for their audience. Substack captured a disproportionate share of that wave because its bundle (newsletter + email list + paid tier + Notes + iOS reader + Recommendations network) is the closest thing to a turnkey independent media business that exists. Founder-led newsletters in particular use Substack to ship build-in-public posts, raise rounds, hire teams, and sell consulting, all while paying 10% of paid revenue instead of building infrastructure. The piece they all eventually want is a personal site or company blog that surfaces their Substack feed front and center, with a Subscribe button that converts visitors from Google, podcast directories, and link-shares into paid readers. That is the use case Poper's Substack widget is built for: a founder, journalist, or independent writer who already has a Substack and wants the brand, discovery, and SEO surface to live on their own domain. Set it up once, and every issue you write flows straight to your site and toward new paid subscribers.