Subshack vs WriteStack: which Substack extension do you need?

Two Chrome extensions come up when Substack writers search for help with Notes: WriteStack and Subshack. They sit next to each other in the store and in search results, which makes them look like alternatives. They overlap on one thing and differ on everything else — and the difference is the one that decides whether you should pay.

This page is written by the team behind Subshack. Every claim about WriteStack below comes from its Chrome Web Store listing and its own site, checked on 25 August 2026; every claim about Subshack is what the extension does today. Where we do not know something, we say so and tell you how to check it yourself.

Disclosure: we make one of these two tools, and we are the free one. That is a reason to read us sceptically, so we have written down the cases where WriteStack is the right purchase and we are not.

The short answer

What each one is

WriteStack is a publishing engine with analytics attached. It batch-schedules Notes, imports drafts, generates note suggestions trained on your published work, filters your Substack notifications into an activity centre, and reports on which Notes converted free and paid subscribers. It also keeps a swipe file: a light-bulb icon next to the share button saves any Note into your drafts while you scroll. At roughly a thousand users it is the most installed Substack extension we found, and it was updated three days before we published this page.

Subshack is a measurement tool. It shows how your Notes and articles actually performed, scores any public Substack profile out of 100 across five axes — positioning, conversion, brand & trust, activity, SEO — and gives you an audience view. It does not schedule, does not draft, does not follow, does not DM and never publishes. The store listing says "Nothing is posted", and that is the whole design.

Where they genuinely overlap

Analytics. Both tell you something about how your Notes did, and pretending otherwise would be dishonest.

The difference is what the number is for. WriteStack's analytics are tied to its queue: which of the Notes you scheduled converted subscribers, so you can schedule more of those. Subshack's are diagnostic and work whether or not you use any scheduler — plus the profile audit, which has no equivalent in WriteStack: it reads your public profile the way a stranger does and names the weakest of the five axes.

If subscriber-conversion reporting is what you want, WriteStack does it and does it well. We do not attach revenue to individual Notes.

Where they differ

Who presses publish. With WriteStack, the tool posts — you schedule, then click Sync and the extension publishes to Substack from your browser session. With Subshack, you post, every time, by hand. If you want Notes going out while you are away from the keyboard, Subshack cannot do that and will not learn to.

The browser has to be running. Because WriteStack publishes through the extension rather than from a server, Chrome needs to be open when a Note is due. That is not a flaw — it is what keeps your credentials out of a third-party server — but a closed laptop means a missed slot. (Schedulers that publish server-side, like SubflowAI, make the opposite trade; we cover that in the full extension roundup.)

Price. WriteStack has no free plan: $23.99/month at the entry tier, $32.99 standard, $99.99 enterprise, after a 7-day trial. Subshack is free, and the profile audit runs in the browser with no account and no extension at all.

Profile. Subshack scores the public surface a reader lands on before they ever read a Note. WriteStack works on the Notes themselves.

Scale of the thing you are trusting. WriteStack has around a thousand users and a longer track record. We are newer and smaller. If install count is your proxy for "will this still exist next year", that comparison does not favour us.

The one question that decides it

Look at your last ten Notes and ask which sentence is true:

• "They were fine, but I posted them whenever I remembered." → Your problem is cadence. Measurement will not fix cadence. Buy the scheduler.
• "I posted them on time and I have no idea which ones worked." → Your problem is measurement, and it is free to fix. Start there, because scheduling more of the wrong shape just makes the wrong shape punctual.

Most people we talk to assume they have the first problem and actually have the second. The tell is whether you can name your best Note of last month without opening anything. If you cannot, a queue is not your missing piece.

Where they do not differ

Both are Chrome extensions that need access to substack.com — and to your custom domain if you publish on one. Both declare on the store that they handle website content and neither declares selling it to third parties. Both are subject to Substack's terms on automated behaviour: scheduling a Note you wrote yourself is low-risk, while bulk following, mass DMs and generic AI replies are the patterns that get accounts flagged and readers irritated. See growing without subscribe-for-subscribe for why the reciprocity shortcuts cost more than they return.

Neither tool can make you interesting. That part is still yours.

Running both

A workflow that makes sense if you have both problems:

1. Monday: run the profile audit and read last week's Notes stats in Subshack. Note which two shapes got replies.
2. Write in those shapes, and load the week into WriteStack's queue.
3. Friday: check WriteStack's conversion view for subscribers, and Subshack's stats for reach and replies. Keep what worked.

They do not see each other and do not conflict.

How to check this page yourself

Extension features change faster than any comparison page — the previous version of this page compared us to a tool that has since stopped being a Substack product altogether. Before you install either one:

• Open the store listing and read the permissions. Be suspicious of anything requesting access to all sites.
• Check the last updated date. An abandoned extension on a fast-changing surface breaks quietly.
• Check the publisher, not the name. Names in this category change often, and at least two pairs of Substack extensions share a name.
• Read what the developer declares about your data on the listing, then the privacy policy. Ours is at /privacy.
• Check current pricing on the vendor's own site. Prices here are what WriteStack advertised on 25 August 2026 and will drift.

WriteStack is on the Chrome Web Store. Subshack is here.

The short version

WriteStack answers "when, and did it pay". Subshack answers "what happened, and how does my profile look". If you already know your Notes work and you need them to go out on time, WriteStack is a real product and worth its price. If you are still guessing which Notes worked, start with the free diagnosis — the Substack profile audit scores your public profile out of 100 without an account or an extension.

For the whole category rather than this head-to-head, see the best Chrome extensions for Substack writers, which checks nine tools against their store listings, and Subshack vs Substack Notes schedulers for the scheduling side in general.