ConvertKit vs Substack: Which Email Platform Is Best for Your Newsletter?

You’ve probably noticed ConvertKit has rebranded to “Kit,” but because most people still search for ConvertKit, I’ll use both names here. Also, this post contains affiliate links (you can read my full disclosure here).

“Should I use Kit (formerly ConvertKit) or Substack for my newsletter?”

I get asked this question at least once a month by service providers who are trying to figure out the best way to stay connected with their network and former clients and get in front of a new audience through email marketing.

Here’s the thing: if you’re asking “Is Substack better than ConvertKit?” you’re actually asking the wrong question.

It’s like asking whether you should blog on your Squarespace site or on Medium. They overlap in purpose, but the approach is fundamentally different: one gives you full control, while the other gives you access to a built-in audience (at the cost of that control).

Before we can address the great Substack vs Kit debate, we need to back up and ask a more important question: What do you actually mean by “newsletter”?

The Purpose of an Email Newsletter

At its core, a newsletter is a way to send educational and/or promotional email messages to a group of people who have given you permission to receive those emails. Those people who can subscribe or opt-in, unsubscribe, or (theoretically) choose what they want to hear about at any time.

Unlike social media, where platforms decide who sees your content, your newsletter lands directly in the inboxes of people who asked to hear from you. There’s very few businesses that won’t benefit from this kind of direct access to their audience, especially given the vast majority of people check their email every day.

The Three Types of Newsletters

Not all newsletters serve the same purpose. I categorize newsletters into three distinct buckets:

1. Thought Leadership

Sharing essays, stories, or reflections to build your voice and ideas. Think of creators who are building an audience around their unique perspective and insights.

2. Updates and Announcements

Keeping readers informed about what’s new: upcoming events, new blog posts, podcast episodes, YouTube videos, features, etc.

3. Marketing and Selling

Promoting your services, products, or offers and reaching out to past and prospective clients to nurture those relationships.

While email marketing softwares such as Kit can handle all three purposes, Substack is really intended for just the first one.

How Substack Works

Substack can be an excellent tool for thought leadership and discovery. New readers might find you through recommendations and engagement with other users on the platform. It’s part blog, part social network, which creates unique discoverability opportunities.

Substack allows you to create your own mini-website for your publication, complete with an about page, archives, and a custom URL. It functions as a home base for your content that readers can browse even if they’re not subscribed.

Substack also allow you to offer paid subscriptions and gate premium content for paying members only. You can have an archive of free content alongside member-only content. It also a built-in podcast platform, and the ability to recommend others on the platform.

What is the downside of Substack?

While there’s substantial controversy surrounding Substack’s very lax content moderation (as noted in The Atlantic’s investigation), we’re going to focus on the platform’s technical drawbacks (rather than its substantial ethical downsides).

But before we dive in, it’s important to note that I’m only familiar with Substack as a user and from having done some research on it previously and for this article.

That being said, I’m also an email marketing consultant, and not a newsletter consultant, so that also impacts the lens through which I look at Substack.

Ok, let’s dive in.

Limited Ownership and Control

While you can export your subscribers from Substack, you’re still renting space on someone else’s platform.

As newsletter consultant Lex Roman, a newsletter strategist who’s written extensively about Substack, beehiiv, Ghost, and other newsletter platforms, points out in their article, “How Substack steals your audience and your revenue“:

“When you send your fans over to subscribe to your publication, they are not just joining your list, they are now joining the Substack userbase. Substack pushes your audience over to their app every chance they get.”

Consider these issues:

• Readers might follow you on Substack without ever truly becoming your subscribers
• Many users turn off email notifications, meaning your content never reaches their inbox. Instead, they’d have to log into the Substack app or website to read your work
• You’re competing not just with other newsletter content, but with a feed of notes, direct messages, and other platform distractions
• Your content lives within Substack’s ecosystem

With email marketing platforms, you show up where your readers already spend a significant part of their day: their inbox. When someone subscribes, they’re opting in to hear from you, not joining another social platform.

Limited Ability to Welcome in New Subscribers

Substack only allows one welcome email when someone subscribes. And for some businesses owners, that’s totally fine! In fact, some people despise multiple onboarding sequences for new subscribers, but I personally prefer a 2-4 email series since that’s when people are most excited to hear from.

Also, you can’t personalize the experience for different subscribers. For example, say Person A signs up for your Substack newsletter directly through your Substack page. By contrast, Person B comes in through a recommendation – and might not have even realized they opted in!

Those two people will still say the same initial email, despite the fact Person B could very well be there by mistake and could use a little reminder as how they got there (instead of wondering how they ended up subscribed).

Limited Ability to Market and Sell

If you’re considering Substack for more than just thought leadership, you need to understand this really significant limitation.

According to Substack’s own Content Guidelines:

“Substack is intended for high quality editorial content, not conventional email marketing. We don’t permit publications whose primary purpose is to advertise external products or services, drive traffic to third party sites, distribute offers and promotions, enhance search engine optimization, or similar activities.”

If your goal is to sell services, promote products, or grow your business beyond the newsletter itself, Substack isn’t designed for that – and it could get your account shut down. (Though, from what I can tell, there are some ways around it.)

To be clear: it’s not that I’m anti-Substack (questionable morals aside). It’s that as an email marketing consultant, these are really significant when you’re doing email marketing!

Substack vs ConvertKit: Feature Comparison

Now that we’ve considered some of Substack’s downsides, let’s dig into how these two platforms compare across key features that matter for your email strategy.

Discoverability

Substack has a robust recommendation system where publications can recommend each other, and new subscribers automatically receive suggestions for similar newsletters. According to Chenel Basilio Growth in Reverse, some creators have grown more than half their audience through Substack’s recommendations alone.

However, as Lex Roman share, “Substack’s analytics are lying to you about how many people found you here. Your best promotion is your fans and other publishers and those are all people, not platforms.”

Kti’s Creator Profile offers similar functionality. You can create a public-facing page that showcases your content, includes an about section, and allows people to browse your published posts. As long as you choose to make your posts public, Kit creates archives just like Substack. (But it does require an extra step when publishing your newsletter.)

While it’s not as robust or well-known as Substack’s recommendation engine, Kit also offers discoverability through their Creator Network feature, where creators can recommend each other and readers can discover new newsletters.

Direct Communication

Substack allows for bi-directional communication, with writers and readers being able to have conversations with the platform. You can also publicly comment on people’s newsletters.

With Kit, subscriber replies come directly to your inbox, so it’s more one-directional (unless someone responds to your newsletter).

Monetization & Gated Content

Both platforms allow you to:

• Offer paid subscriptions
• Gate premium content for paying members only
• Maintain free archives alongside member-only content
• Build an audience before introducing paid tiers

Kit handles this through their Commerce feature, while Substack has it built into the core platform.

To be fair, Kit’s requires some technical setup on your hand to make this happen, whereas Substack handles this automatically on their end.

But, worth noting that Substack takes 10% of all paid subscription in addition to Stripe’s processing fees. As Chenell Basilio from Growth in Reverse notes, “When you’re starting out, this might not seem like a lot. But as you grow it can become a huge chunk of change.”

By comparison, with Kit you keep 100% of your subscription revenue through their Commerce feature (you only pay Stripe’s processing fees).

Segmentation & Personalization

If you work with different types of clients or want to send targeted content to specific audience segments, Substack’s limitations become a real constraint since you can only separate subscribers by paid vs free subscribers. You can’t tag people based on their specific interests or create subscriber segments the way you can with Kit, which allows you to:

• Tag subscribers based on interests, behaviors, or actions they take
• Send different content to different segments of your audience
• Personalize emails with subscriber-specific information
• Create complex subscriber journeys based on multiple data points

Automation & Sequences

Kit allows you to create automated email sequences based on behaviors such as signing up for a freebie, expressing interest in a product or service, making a purchase, while Substack only offers a single welcome email when someone subscribes.

With Kit and many other email marketing softwares, you can:

• Set up welcome sequences and evergreen newsletters for new subscribers
• Create automated follow-ups based on subscriber actions
• Deliver digital products or courses automatically

Advanced Marketing Features

While both tools allow you to track things like open rates, links clicked, subscriber growth, Kit offers more robust features. For example, with Kit, you can

• Design custom landing pages and forms
• A/B test subject lines and content
• Create sales funnels and promotional campaigns

Substack vs ConvertKit: Key Feature Comparison

Here’s a quick comparison table to show you how Kit and Substack compare. (Again, remember, this is from the perspective of someone who does email marketing specifically!)

Kit vs Substack: The Decision Frameworkb

Before choosing between Kit (or any email marketing software) and Substack, here are three questions to ask yourself:

Question 1: Is your newsletter itself the product?

If YES → Consider Substack (or beehiiv, which bridges the gap between Substack and traditional email marketing)

If NO → Choose Kit or another email marketing platform

If you plan to monetize through paid subscriptions and the newsletter is your primary offering, Substack’s built-in payment processing and recommendation network can work well. But if the newsletter supports your business rather than being your business, you need more flexibility.

Question 2: Will you need to segment and personalize content?

If YES → Kit (or similar email service provider) is essential

If you work with different types of clients, offer various services, or want to send targeted content to specific audience segments, you need the tagging and segmentation capabilities of a proper email service provider.

If NO → Substack might suffice

If everyone gets the same content and you’re not differentiating between subscriber types, Substack’s simpler approach may be adequate.

Question 3: Do you want to ensure content reaches inboxes (rather than relying on an app)?

If YES → Kit (or similar email service provider)

When you send an email through Kit, it goes directly to subscriber inboxes (unless they unsubscribe or you’re having technical issues with your email deliverability).

With Substack, users can disable email notifications and only read via the app or website – and then technically they might not even be subscribed to your newsletter anymore!

For Flexibility → Substack

Readers can choose how they engage with your content, which some appreciate but which dilutes your ability to reach your entire audience.

As a Certified Kit Expert and email automation strategist, for most credentialed professionals selling their services, Kit is the better long-term choice.

Ultimately, this isn’t about one being “better” than the other. In fact, some business owners have found creative ways to use Kit and Substack together.

It’s about understanding what you intend to do with your newsletter, and choosing the tool that’s actually designed for that purpose.