I Checked My Last 40 Substack Subscriptions. Only 7 Were Confirmed as Mutual.

My subscriber count was rising.

My open rate was falling—from 34% to 18%.

A subscriber is not always a reader. Some people find your work and genuinely want more. Others arrive through a subscribe-for-subscribe thread, ask you to return the favor, and eventually drift away.

Both increase your subscriber count. But they do not build the same audience.

The question Substack makes difficult to answer

You’ve probably seen this message:

“Subscribed ! Your turn.”

You subscribe back. A few days later, you have no simple way to check whether that account is still subscribed to you. Once is easy. Forty times is not.

So I built the Substack Subscribe-Back Checker. It reads a public profile’s subscription list and sorts every publication into three groups:

• Mutual — both sides are subscribed today.

• One-way — you subscribe to them; no subscription back is publicly visible.

• Publicly unverifiable — they keep their subscriptions private, so nobody can check either way.

I ran it on my own list first

I subscribe to 488 publications. The free scan reads the 40 most recent. The ones where a subscribe-back would still be recent enough to matter.

7 mutual. 19 one-way. 14 publicly unverifiable.

Seven. I had expected something closer to half.

That third number matters as much as the first. A private list stays private, and Subshack never opens it. Unverifiable means unverifiable not “they didn’t.”

A one-way subscription is not a betrayal

I subscribe to plenty of writers who will never subscribe to me. That is normal. I read them.

The better question is the other one: how many newsletters sit in your inbox only because you once felt obliged to return a subscription?

The checker never accuses anyone. It describes a relationship as it looks today. Someone may have used another account, or unsubscribed later. That is why a one-way result is a lead to review, never a verdict.

Check your own list

Before you scan, guess your number. Under 20%? Around 40%? More than 60%? Then run it and compare.

Check who subscribed back — free

No account, nothing to install. The free scan covers your 40 most recent subscriptions and gives you every total. To cover all of them — mine were 488 — the Subshack Chrome extension runs the same check from your own browser, under Audit › Sub-for-sub.

A bigger number feels like progress. Knowing who is actually behind it is more useful.