Compose for Substack uses the bare minimum of your Substack information in order to function.
Information NOT stored:
Password: Compose uses your password, if you have one, only to retrieve the cookie Substack uses to authenticate create/edit post requests. Your password is not and will never be stored.
Email contents: The contents of your email newsletters and your account information is also not stored or tracked in any way.
Subscriber list: The app does not access or track your subscriber list in any way.
Information Compose DOES store:
Everything on this list is stored locally and will never be shared with outside parties.
Cookie: Upon login, Substack uses a cookie to authenticate requests to create and edit posts. Compose locally stores this cookie so you can create and edit posts in the app.
Substack sub-domain: Some operations, such as creating or scheduling posts, require sending a request to that newsletter’s specific sub-domain. Compose stores the sub-domain of your newsletter in order to create, edit and schedule posts.
Email: Compose stores your email address locally in order to:
- Prefill the “Send Test Email” field, so you can send test emails to yourself
- Track how many posts are left in your free trial
Your email will never be shared with an outside party or spammed.
Substack Author ID: Compose locally stores your author ID number in order to create new posts.
Clipboard contents: On opening the login page, Compose will check your clipboard for one of the links Substack emails you to use to log in. This is important because Substack allows users to not set a password on their account and to only log in via email. The clipboard is not read anywhere else in the application (as you can verify on iOS and iPadOS 14).
My app’s promise
Let me be clear. I am not interested in any kind of gross business model involving selling users’ personal information.
I want Compose to be the absolute best writing experience possible so you will want to subscribe. To my mind, a great writing experience means never having to worry if you are the product.
With Compose, direct user support means there’s no skeezy middleman. It means everyone’s interests are aligned - you want a great writing app, and I want to earn your subscription by delivering a great writing app.