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How to find Substack newsletters to sponsor (with real subscriber counts)

Newsletter ads work when the audience fits. Here is how to build a list of Substack newsletters in your niche with subscriber counts, contacts and how active they are.

Newsletter sponsorships are one of the few ad channels where people still read the ad. The catch is finding the right newsletters: ones your customers actually read, that are still active, and that are big enough to matter but small enough to afford.

Substack hosts thousands of them. Here is how to build a shortlist.

What makes a newsletter worth sponsoring

Before you search, decide what "good" means for you:

  • Fit. The topic matches your customer, not just your industry. A newsletter about "AI tools for lawyers" beats a general AI one if you sell to law firms.
  • Size. Subscribers between 2,000 and 50,000 are usually the sweet spot for small budgets. Big names are expensive and often sold out.
  • Activity. It posts every week or two. A newsletter that last posted three months ago is dead, whatever its subscriber count says.
  • A paid tier. Writers with paying readers usually have a more engaged audience.
  • A real person you can reach. You need an email, X or LinkedIn to pitch them.

The manual way

  1. Go to substack.com and search your topic.
  2. Open each newsletter, note the subscriber count if it is shown, and check the date of the last post.
  3. Look at the "About" page and the author profile for contact links.
  4. Put everything in a spreadsheet.

It works, but it is slow: 10 to 15 minutes per newsletter, and many hide the subscriber count on their own page.

The fast way

I built Substack Newsletter Finder for exactly this. You give it keywords or categories and it returns a table:

  • newsletter name and URL
  • subscriber count and the author's follower count
  • the author's X, LinkedIn, YouTube and website links
  • last post date and how many posts in the last 30 days
  • language and whether it has a paid plan
{
  "searchQueries": ["b2b saas", "startup marketing"],
  "minSubscribers": 2000,
  "activeWithinDays": 30,
  "language": "en",
  "maxResults": 200
}

200 newsletters cost about $0.50. Filter by subscribers and activity, sort, and you have a shortlist in a few minutes.

How to pitch

Keep the first email short and specific:

  • one line on why their audience fits ("your readers are early stage founders, we make invoicing for them")
  • what you want: one sponsored slot in an upcoming issue
  • ask for their rate, or offer one if they do not have a media kit

Start with three to five newsletters, not fifty. Run one slot each, track signups with a separate link or code per newsletter, and only rebook the ones that paid back.

Read before you buy

Before paying, read the last five issues. Check that the writing is good, that ads are clearly marked and not stuffed in, and that readers reply or comment. Ten minutes of reading saves you from buying space in a newsletter nobody opens.

A shortcut for writers too

If you run a newsletter yourself, the same list works in reverse: find newsletters of a similar size in your niche and propose a cross promotion. Both of you grow, nobody pays.