Your checkout and your MailerLite list, finally talking.
Checkout Sync puts every Paddle, Lemon Squeezy and Polar buyer into the right MailerLite group, with the product, price and links saved on their profile. Refunds, cancellations and failed payments come through too, so each one can start the right email, like a friendly "your card didn't go through".
Paddle Lemon Squeezy Polar
Your payment for Budget Club didn't go through
Hi Maya,
Your latest payment of $12.00 for Budget Club didn't go through. That usually means a card expired or the bank declined it.
Update your card
If something else is going on, just reply and I'll help.
Connect MailerLite
Make an API token in MailerLite and paste it in. That's the whole MailerLite side.
Connect your checkout
Paste a Paddle key and we add the webhook for you. For Lemon Squeezy or Polar, you add one webhook URL and copy a secret across.
Start the right email
Buyers join groups like Bought: Budget Club, Payment failed or Canceled. A MailerLite automation with the trigger Joins a group does the rest. One button sends a test to your own address first.
The emails that earn their keep
Payment failed. Send a friendly "your card didn't go through" note with a link to update their card, before the subscription lapses.
Canceled. Say goodbye kindly, ask why, or make a win-back offer while they still have access.
Refunded. Take them out of the upsell for a product they just sent back.
Bought. Welcome new customers and send the onboarding emails for the exact product they bought.
Groups Checkout Sync keeps up to date Example
Your page in Checkout Sync
This is the real settings page, filled with example numbers: what synced this month and which checkouts are connected.
How it compares
Swipe the table sideways to see every column →
| Checkout Sync | Zapier | Make | MailerLite's own | |
|---|---|---|---|---|
| Paddle, Lemon Squeezy, Polar into MailerLite | Ready to use | Ready-made Lemon Squeezy and Polar apps, one Zap per event. Paddle needs a lookup step too | You build the scenarios | No Paddle, Lemon Squeezy or Polar |
| Cost | Free for 25 sales a month, then from $15 | Paddle's lookup step needs a paid plan, about $20 a month billed yearly | Free plan works; paid plans for more | Free, but not for these three |
| Payment failed cleared when they pay | Yes | You build it | You build it | n/a |
| Same order never counted twice | Yes | You handle it | You handle it | n/a |
| Writes the emails for you | No: your MailerLite automations send them | No | No | No |
Questions
Which checkouts work?
Paddle Billing, Lemon Squeezy and Polar: sales, renewals, refunds, cancellations and failed payments. For Stripe, MailerLite has its own integration.
What lands in MailerLite, exactly?
The buyer, added or updated, with thirteen Checkout fields (product, plan, amount, status, order number, receipt link, update-card link and more), and the groups you choose. In an email you write {$checkout_product} and MailerLite fills it in. See every field.
Does it work on MailerLite's free plan?
Yes. The API, groups, custom fields and group-triggered automations are all on the free plan. It allows 3 automations and 250 active subscribers. On Checkout Sync's Free plan, start with a welcome (Customers) and a Refunded check-in: those groups are joined on every plan. Payment failed and Canceled join their groups from Checkout Sync's Lite plan, so add those emails when you move up. Mind the 250: past it MailerLite pauses sending and adding subscribers (details). Mind the 2,500 emails a month too: every automation email counts. Checkout Sync warns you from 200 subscribers, and you can switch to only updating people already on your list.
What if a buyer isn't on my list?
You choose one of three: add them, and put those who didn't agree to marketing at checkout in a Not opted in group (the default); add everyone; or only update people already on your list. Each buyer you add counts as an active subscriber on your MailerLite plan.
Why not Zapier or Make?
You can, with one Zap per event. Zapier has ready-made Lemon Squeezy and Polar apps; Paddle has none, and its webhooks don't include the buyer's email, so each Paddle Zap needs an extra lookup step, which Zapier's free plan doesn't allow (paid plans start around $20 a month, billed yearly). On any of the three you still build and maintain each Zap yourself. Checkout Sync does the lookup, names the product on refunds and renewals, takes people out of Payment failed once they pay, and never counts the same order twice. It's free for 25 sales a month, and paid plans start from $15 a month.
Make's free plan can do it too, if you build the scenario yourself (a webhook, the lookup at Paddle, then the MailerLite steps for each kind of event) and keep it working as things change. Checkout Sync is the no-build version: product names on every event, Payment failed cleared when they pay, no double counting when a checkout resends, and an import of past customers.
What does the update-card link do?
It depends on the checkout. Paddle: the buyer lands on Paddle's own page, enters their email, and Paddle emails a sign-in link to the card page. Lemon Squeezy: a link to the buyer's billing page. Polar: your Polar customer portal, which is the same page for every buyer. Where a checkout sends no link, the field stays empty and your settings tell you, so give your email a fallback link.
Why not a failed-payment tool like ChurnWard?
Those tools retry cards and write the emails for you, and they cost more (ChurnWard is $29 a month). Checkout Sync does neither: it puts each buyer in the right MailerLite group and fills in their fields, and your own MailerLite automations send the emails. It doesn't retry cards (your checkout does that) and doesn't act on paused Paddle subscriptions yet.
Is it OK to email my buyers?
MailerLite's anti-spam policy lists, among the addresses that are OK to send to: "Customers who have purchased from you within the last 2 years." For newsletters, the default setting puts buyers who didn't opt in at checkout in a Not opted in group, so you can leave them out.
What does it cost?
Free for 25 sales a month. Already on Free from before paid plans opened? You keep up to 1,000 sales a month until December 1, 2026, and your settings say so. Paid plans start from $15 a month: Lite is $15 for 100 sales, Starter $29 for 1,000, Pro $69 for 10,000. Refunds, cancellations, failed payments, free orders and test orders never count. On Free, Canceled and Payment failed are recorded and their fields written; they join their groups (and start automations) on Lite and up. See pricing.
What about my past orders?
Import them from your settings: the last 30 days, 90 days, a year or everything. Past buyers get their Checkout fields filled in and, unless you tick the box, join no groups, so nobody gets a surprise email. If you do tick it, keep the range to a year or less: MailerLite's anti-spam policy only lets you email buyers from the last 2 years without other permission (buyers who opted in to your emails are fine at any age). Imports never count toward your plan.