Open source · AGPL-3.0 · Built on Cloudflare
Newsletter software built for AI agents
FlockStack is an open-source newsletter platform, an alternative to beehiiv and Substack. Write an issue, send it to your list and publish it on your own domain, or let an AI agent do it: everything the dashboard does is also in a REST API and an MCP server. Start free, then pay for the emails you send, not for dormant subscribers.
Your data is stored in the United States. Keep it in the European Union instead
- Free plan
- $0
- 2,500 subscribers, 10,000 emails
- Paid plans from
- $9 a month
- 25,000 emails
- Paid plans up to
- $299 a month
- 2,000,000 emails
How it works
Write it, send it, publish it
Write an issue
Draft it in the editor, add your images, then send it now or schedule it for later.
Send it to your list
Import your subscribers from a CSV, or collect them with a signup form. Welcome emails and double opt-in are built in.
Publish it on the web
Every issue lands in an archive on your own domain, next to a signup form for new readers.
Features
The same features on every paid plan
A bigger plan raises the limits: emails, subscribers, imports and AI writing requests. The Free plan has 1 newsletter, 2 automations, and a dedicated IP is an add-on from Pro.
Write and send
Campaigns and scheduling
Write an issue, send it now or schedule it.
Welcome emails
A first email for every new subscriber.
Welcome series and follow-ups that start from a signup, a tag, a purchase or a date.
Double opt-in
Subscribers confirm their address before they join.
CSV imports
Bring your list from beehiiv, Substack, Mailchimp, Kit and others.
Open and click stats
See how every issue did.
Publish
A website with an archive
Your issues live on a public site of their own.
Signup forms
Collect subscribers on your site, or anywhere else.
Custom domain
Serve your site from your own domain.
Charge readers through your own Stripe account. FlockStack takes 0% of what you sell.
No “Powered by” badge on paid plans
Your newsletter carries your name, not ours. The Free plan adds a small “Sent with FlockStack” link.
Deliverability, on by default
Warm-up sending
Big sends go out gradually while your sending reputation builds.
List cleanup
Readers who stop opening get one last chance, then stop receiving issues. Nobody is deleted.
Bounce and complaint limits
A campaign pauses when bounces or spam complaints climb too high.
One-click unsubscribe
Readers can leave in one click, right from their mail app.
API, agents and sign-in
Everything the dashboard does, from your own code.
Let ChatGPT, Claude, Cursor or Codex run your newsletter, under the same checks as the dashboard.
Passkey sign-in
Sign in with your device. No password to leak.
Pricing
Start free, then pay for the emails you send
Free up to 2,500 subscribers and 10,000 emails a month, with no card. Past that, pick the emails you send in a month. Yearly plans cost 10 months instead of 12.
25,000
for up to 5,000 subscribers
Starter
$9/month
Billed monthly · $0.36 per 1,000 emails
Past 25,000: $0.15 per 1,000 extra emails, up to a limit you set.
Create your accountYou choose and pay for a plan after you have set up your newsletter.
Every paid plan includes
- Campaigns
- Scheduling
- Website
- Your own domain
- Signup forms
- Welcome emails
- Imports
- Stats
- AI agents and API
Dedicated IP add-on, your own sending IP for steady volume: $27 a month on Pro, Scale and Max, billed monthly, also beside a yearly plan. At cost. AWS charges us $24.95 a month for your own sending IP and card fees come to about $1.50; you pay $27 a month, with no markup on top. We make our money from your plan, not your IP.
Sending more than 2,000,000 emails a month, or past 400,000 subscribers? Tell us what you need, or email hello@flockstack.io
Our price promise
90 days' notice
If a price goes up, we email existing customers at least 90 days before it takes effect. Until then, you keep paying the price you have.
Published prices
Every plan, add-on and price is on this page. Past your plan's emails, extra emails are $0.15 per 1,000, up to a monthly limit you set. Nothing else is billed on top of your plan.
No cut of your sales
Readers pay your own Stripe account, and FlockStack takes 0% of what you sell. Stripe's own fees apply.
The terms of service say the same.
Compared with beehiiv and Substack
Up to 92% less than beehiiv for a weekly newsletter
A weekly newsletter to the same subscribers, side by side with beehiiv's published prices, checked October 2026.
FlockStack Free, $0
2,500 subscribers, 10,000 emails a month
2 automations, besides the welcome email
beehiiv Free, $0
Up to 2,500 subscribers
No automations
| A weekly newsletter to | FlockStack | beehiiv | You save |
|---|---|---|---|
| 5,000 subscribersFlockStack Starter, 25,000 emails a month | $9/mo | $109/mo | 92% |
| 25,000 subscribersFlockStack Growth, 125,000 emails a month | $29/mo | $199/mo | 85% |
| 50,000 subscribersFlockStack Pro, 250,000 emails a month | $59/mo | $299/mo | 80% |
| 100,000 subscribersFlockStack Scale, 500,000 emails a month | $109/mo | $469/mo | 77% |
| 400,000 subscribersFlockStack Max, 2,000,000 emails a month | $299/mo | Enterprise only on beehiiv | |
Billed monthly.
beehiiv prices by subscribers, with unlimited sends; FlockStack prices by the emails you send. The comparison assumes a weekly newsletter, about 5 emails per subscriber a month, which each plan's emails cover. Sending daily? Extra emails are $0.15 per 1,000. beehiiv's prices are its Lite plan on beehiiv.com/pricing, as of October 2026. The Free plans above are each plan's published limits: beehiiv's Free stops at 2,500 subscribers, and FlockStack's adds a small “Sent with FlockStack” link.
Three months, worked out
Substack charges nothing to publish and takes a share of paid subscriptions, so its cost depends on what you earn.
A weekly free newsletter
5,000 subscribers, a weekly issue: 25,000 emails a month.
- FlockStack
- $9/mo
- Starter plan
- beehiiv Lite
- $109/mo
- Unlimited sends
- Substack
- $0/mo
- Nothing to publish
A weekly newsletter with paid readers
25,000 subscribers, a weekly issue, 5% paying $8 a month: 125,000 emails a month, $10,000 a month from readers.
- FlockStack
- $29/mo
- Growth plan
- beehiiv Lite
- $199/mo
- Unlimited sends
- Substack
- $1,000/mo
- 10% of paid subscriptions, nothing to publish
A daily newsletter to a big list
100,000 subscribers, a daily issue: 3,000,000 emails a month.
- FlockStack
- $449/mo
- Max plus 1,000,000 extra emails ($150.00)
- beehiiv Lite
- $469/mo
- Unlimited sends
- Substack
- $0/mo
- Nothing to publish
Where we are the weaker pick
Substack costs nothing until you earn
If you want to publish for free at any size and don't mind giving up 10% of paid subscriptions, Substack's price is hard to beat, and it brings readers with it. FlockStack has no reader network of its own beyond a small recommendations directory.
A daily sender pays more here than a weekly one
FlockStack counts emails, so a daily newsletter to a big list narrows the gap with beehiiv's unlimited sends. The scenarios below show a case where the gap is only a few percent.
We have no mobile app and no enterprise paperwork
FlockStack has no app of its own, no SOC 2 report and no SSO. If a buyer's checklist needs those, FlockStack is not ready for you yet.
This page leaves features out
It compares prices and fees we could check on each company's own pages on the date shown. It does not compare editors, ad networks, recommendation features or deliverability, which we haven't tested side by side.
The full comparison with sources, which also sets FlockStack beside Kit and Mailchimp
Questions
Good to know
Is FlockStack open source?
Yes. FlockStack is licensed under the AGPL-3.0: you can read the code, change it and run it on your own server.
FlockStack Cloud, at flockstack.io, runs the same code for people who would rather not host it.
Where does my data live?
On Cloudflare, in the region you pick when you sign up: the United States or the European Union. Your newsletters, subscribers and campaigns are stored in D1, and your images in R2, in that region. An account lives in one region. The docs list where each kind of data is stored.
Can I import from beehiiv or Substack?
Yes. Export your subscribers as a CSV from beehiiv, Substack, Mailchimp, Kit or another platform, and import the file. The exports work as they are.
Is there a free plan?
Yes. Free is $0 with no card: 2,500 subscribers, 10,000 emails a month, one newsletter, your own sending and archive domain, polls, surveys, forms, the API and MCP, and 2 automations besides the welcome email. In return, your emails and website carry a small “Sent with FlockStack” link, which any paid plan removes.
Free can't go past its limits: at the email limit, a send that wouldn't fit is refused up front, with the numbers, and nothing is billed. Your first 3 campaigns go to 500 people at most while we get to know your sending.
Substack is free to publish at any size and takes 10% of paid subscriptions, and beehiiv's Free plan stops at 2,500 subscribers. FlockStack takes 0% of what you sell.
What happens when I hit my email limit?
On Free, nothing is billed: a campaign that wouldn't fit in the month's emails is refused up front, with the numbers, until the month resets or you upgrade. On a paid plan, sending goes on: extra emails cost $0.15 per 1,000, billed with your plan at the end of the period. You set a monthly limit on them on the billing page, the plan's own emails by default, and we email you at 80% and 100% of it.
At that limit, campaigns and welcome emails pause until you raise it, upgrade or the next month starts. Signups keep working, and confirmation emails still go out. A paid plan that ends puts the account on Free: nothing is deleted, but campaigns wait until it is under Free's limits or you upgrade.
Each plan also sets how many subscribers you can hold, shown next to its emails in the pricing slider.
Do you offer SOC 2, SSO or a custom plan?
A custom plan, yes, for lists with over 400,000 subscribers or over 2,000,000 emails a month: limits set for you, a dedicated IP included, help moving over from beehiiv, Substack or another platform, and a direct line to the people who build FlockStack. There is no price list: tell us what you send and we reply personally within 2 business days.
SOC 2 and SSO, no. FlockStack doesn't have SOC 2, SSO or SAML, SCIM, audit logs, an uptime SLA and team seats with roles yet. We build them when customers need them, so the form asks which you would need and we build the right ones first.
Can AI agents use it?
Yes. Everything the dashboard does is also in the REST API and in an MCP server, so ChatGPT, Claude, Cursor or Codex can write, schedule and send for you, under the same checks and limits as a person.
Is there a mobile app?
No, FlockStack has no app of its own. The dashboard works in a phone's browser, and the ChatGPT and Claude mobile apps can use FlockStack through its MCP server.
Start your newsletter
Create your account, import your list and write your first issue.