Substack Social Preview — Fix and Test Your Newsletter Link Preview

Substack generates Open Graph tags for every post and your publication homepage. When you share a Substack post on Twitter, LinkedIn, or in someone's Discord, the preview card shows your cover image, post title, and a description snippet.

Substack handles most of this automatically, but there are still things that break: wrong cover image, description truncated at an awkward point, or the preview pulling from the wrong post when a URL is reused. Testing your Substack links before sharing catches these problems in seconds.

How Substack Generates OG Tags

Substack automatically generates Open Graph tags for every post. The og:title matches your post headline. The og:description is generated from your post's subtitle or the first few sentences of the body if no subtitle is set. The og:image is the cover image you upload when writing the post.

For your publication homepage, Substack uses your publication name as og:title and your publication description as og:description. The og:image is your publication logo or cover image.

What Substack sets automatically

• og:title — your post title
• og:description — post subtitle or opening excerpt
• og:image — your post cover image
• og:url — the canonical post URL
• og:type — article
• twitter:card — summary_large_image
• twitter:image — same as og:image

Because Substack controls the meta tag generation, you cannot directly edit the HTML. Your control comes from setting the right post metadata in the Substack editor.

Setting OG Tags in the Substack Editor

In the Substack post editor, the fields that control OG tags are in the post settings panel.

Cover image (og:image)

Upload a cover image for every post. This becomes the og:image. Substack recommends 1600x900 pixels but 1200x630 also works. The cover image appears at the top of the post and in all social preview cards.

Subtitle (og:description)

The subtitle field (shown below the title in the editor) becomes the og:description. Write a subtitle that reads well as a social preview description — under 155 characters, giving enough context to make someone want to read the post.

Post title (og:title)

Your post title is the og:title. Keep it clear and descriptive. Substack does not truncate the og:title, but Twitter and LinkedIn will if it runs long. Keep headlines under 70 characters for clean display on all platforms.

For the publication homepage

In your publication settings, the Logo Image and Description fields control the og:image and og:description for the homepage. Keep the description under 155 characters for clean display everywhere.

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Testing Your Substack Post Preview

You can test a live Substack post using the HTML paste method in the OG checker.

1. Open your published Substack post in a browser
2. Press Ctrl+U to view the page source
3. Copy all the HTML
4. Paste it into the OG checker's HTML tab
5. Click Check Tags

The results show the og:title, og:description, and og:image Substack generated for your post, plus preview card renders for Facebook/LinkedIn and Twitter/X.

Testing before publishing

Substack does not offer a draft preview URL that works with external tools. To test before publishing, use Substack's built-in "Send test email" feature which includes the preview card, or publish as a free post and immediately unpublish after checking if you need a full preview test.

What to look for

• The cover image appears at full width in the Facebook/LinkedIn card
• The og:description reads well and is not truncated at an odd point
• The title matches what you intended (no encoding issues with special characters)
• The og:url matches the canonical post URL

Fixing Substack Preview Problems

Because Substack generates OG tags from your post content, fixing preview problems means updating the post settings rather than editing HTML.

Cover image not showing in preview

If the preview shows no image, check that you uploaded a cover image to the post in the Substack editor. If the image is there in the post but not in the preview, it may be a caching issue — use Facebook's Sharing Debugger or Twitter's Cards Validator to force a re-scrape.

Wrong description in preview

Edit the post in Substack, update the subtitle field, and republish. Then use the platform debug tools to force a preview refresh.

Slow loading preview on first share

Substack's cover images can be large. Platform scrapers time out on slow image fetches. If the cover image file size is very large (over 1MB), consider compressing it. Substack processes uploaded images but does not always reduce file size significantly for large uploads.

Old preview showing for updated post

If you updated the post title, subtitle, or cover image after publishing, the old preview may be cached. Use the Facebook Sharing Debugger (click "Scrape Again") and LinkedIn Post Inspector to force fresh fetches.

Frequently Asked Questions

Can I set a custom og:image for a Substack post that is different from the cover image?

No. Substack uses the post cover image as the og:image — you cannot set a separate og:image. The cover image serves double duty as the in-post header image and the social preview image. Design your cover image to work well in both contexts.

Why does my Substack post show the wrong preview on LinkedIn after I updated the cover image?

LinkedIn cached the old preview when the post was first shared. Go to linkedin.com/post-inspector, enter your post URL, and click Inspect to force LinkedIn to re-fetch the updated page. The new cover image should appear in the preview after the refresh.

Does Substack set different OG tags for free posts vs paid posts?

The OG tag structure is the same for both. Paid posts may show a "This is a paid subscriber post" snippet in some platform previews since Substack adds that to the page metadata, but the core og:title, og:description, and og:image are generated the same way regardless of post paywall status.