Mailchimp vs MailerLite

How each tool stores a B2B contact list

Mailchimp's own guidance in Getting Started with Your Audience is to keep one primary audience and use tags, groups or segments to organise people inside it. That advice matters because audiences are independent: the import guide says Mailchimp cannot detect duplicates, bounces or unsubscribes across multiple audiences, so a trial user who also sits on your customer list can receive both mailings. A subscriber record carries merge fields from your import columns, and any column you do not map is dropped.

MailerLite organises people into groups and attaches custom fields. The fields endpoint accepts text, number and date types, and the subscribers endpoint distinguishes five statuses: active, unsubscribed, unconfirmed, bounced and junk. That richer status model is useful when you audit a list before a migration, because you can filter bounced and junk addresses out of the export instead of paying to carry them.

• Neither tool has a company object. Put the account ID or plan name in a field (Mailchimp) or custom field (MailerLite) and build segments on it.
• For a product with trial, paid and churned users, create one group or tag per lifecycle stage and let your backend move people between them.

Automation for onboarding and trial-conversion flows

MailerLite's automation page lists the entry triggers: joins group, clicks a link, completes a form, updates field, date-based, and several store triggers such as abandoned cart. A single automation can have up to three triggers. Inside the flow you get delay, condition and A/B test steps, and actions that send mail, call a webhook, update a field, copy or move the subscriber between groups, or jump to another step. Conditions can split on campaign activity, segment or group membership, automation activity and custom fields.

There is no custom product-event trigger in that list, which is the main gap for a SaaS team. The practical workaround is a field: your backend upserts the subscriber through the API and writes something like a trial_ends date or an activated flag, and an automation starts on 'updates field'. Because MailerLite's upsert is non-destructive (omitted fields and groups are left alone), a nightly sync from your database will not wipe data.

Mailchimp's automation overview separates plans: the Free plan allows a single email automation, while a full customer-journey workflow needs Standard or Premium. Its plan list shows basic flows on Essentials and enhanced flows on Standard. The page describes triggers built on signups, store events and engagement; it does not describe an events endpoint comparable to a send-event call, so confirm in the Marketing API reference whether your product events can start a journey before you rely on it.

Transactional email: both vendors send you elsewhere

MailerLite's automation FAQ is direct about the boundary: it is a marketing tool, and password resets or order confirmations belong in MailerSend. That is a second product, a second sending domain setup and a second bill.

Mailchimp's transactional page explains that Mandrill was renamed Mailchimp Transactional in fall 2025. It has its own Transactional API, can import your Mailchimp templates, and lets marketers edit transactional templates without a developer. The page shows no price, so the cost of that product has to come from Mailchimp directly. For a B2B SaaS the safe plan is the same on both sides: send system mail from a dedicated transactional sender and keep marketing on the marketing plan.

API, webhooks and rate limits

MailerLite documents its REST API at developers.mailerlite.com. Requests go to connect.mailerlite.com/api with a bearer token, there are official libraries for PHP, Go, Node.js, Python, Ruby and Rust, and the global limit is 120 requests per minute. Import-creation endpoints have their own limit of 5 requests per minute, so large backfills should use the batch endpoint. Each API key is tied to the user who created it, and it stops working if that user is removed, which is worth remembering when an employee leaves.

Its webhook list covers subscriber created, updated, unsubscribed, bounced, added to or removed from a group, automation triggered and completed, spam reported, plus campaign sent, opened and clicked. A delivery counts when your server answers with a 2xx code; failures are retried three more times, after 10, 100 and 1000 seconds. Mailchimp links its Marketing API reference and an audience-webhook guide from its developer menu; compare both against the two or three calls your product will actually make before you commit.

Cost at 5,000, 10,000 and 25,000 contacts, with the arithmetic

At 5,000 contacts receiving three emails a month (15,000 sends), the send allowances are no constraint on any plan. Mailchimp Standard at list price is $100 a month, or 12 x $100 = $1,200 a year; with the 12-month offer it is $50 a month, or $600 in year one. MailerLite Comfort is $49 a month, or $588 a year, and Power is $69 a month, or $828. Year one is almost a tie between Mailchimp's offer and Comfort ($600 against $588). Over two years Mailchimp costs $600 + $1,200 = $1,800, Comfort $1,176 and Power $1,656.

At 10,000 contacts receiving four emails a month (40,000 sends), Mailchimp Standard is $135 a month, $1,620 a year, or $810 in the offer year at $67.50. Comfort is $89 a month, $1,068 a year; Power is $129 a month, $1,548 a year. In year one Mailchimp's offer is cheapest at $810. Over two years Mailchimp totals $810 + $1,620 = $2,430, Comfort $2,136 and Power $3,096. Comfort wins on cost by $294; Power costs $666 more than Mailchimp, and what that money buys is the removal of the send cap.

At 25,000 contacts receiving four emails a month (100,000 sends), Mailchimp Standard is $310 a month, $3,720 a year, or $1,860 in the offer year at $155. Comfort is $179, $2,148 a year; Power is $239, $2,868 a year. Over two years Mailchimp totals $1,860 + $3,720 = $5,580, Comfort $4,296 and Power $5,736. At this size Power and Mailchimp are within $156 of each other over two years, so the choice should rest on features and integrations, not price.

Heavy senders change the picture. A product that mails 10,000 contacts 15 times a month sends 150,000 emails. Mailchimp Standard allows 12 x 10,000 = 120,000, and Mailchimp's pricing page says overages apply when a send limit is exceeded; its additional charges article explains how they are billed. MailerLite Comfort allows 10 x 10,000 = 100,000, so it is also over. Power has no cap, which makes $129 a month the only predictable price in this example.

• All prices above are the monthly list prices on the Mailchimp and MailerLite pricing pages, read on 2026-10-07.
• Mailchimp's 12-month offer carries its own terms; confirm eligibility before you plan a budget on it.
• MailerLite annual billing shows a discount at the 500-subscriber tier ($10.80 against $12 for Comfort); the larger tiers above are monthly prices, so ask for the annual figure at your size.

What the cheaper plans leave out

• Mailchimp Free: 1 audience, 250 contacts, 500 sends a month and 250 a day; sending pauses if you pass the limit. Essentials: 3 seats, 10 times your contacts in monthly sends, basic automation flows, and custom-coded templates you can create but not send.
• Mailchimp Standard: 5 seats, 12 times contacts in sends, enhanced automation flows. Premium starts at $350 a month at 500 contacts, with 15 times contacts in sends and unlimited seats.
• MailerLite Free: 250 subscribers, 2,500 emails a month, 2 seats. Comfort: 10 times your subscriber tier in monthly emails. Power: unlimited monthly emails.
• Neither marketing plan includes transactional sending (see the section above).

Moving from Mailchimp to MailerLite

1. Export from Audience in Mailchimp. The export guide says you can export an entire audience, a segment, a tag or a group, and the result may be a ZIP with separate CSV files for subscribed, unsubscribed, non-subscribed and cleaned contacts. Only Owners and Admins can export audiences, and the files are kept for 30 days.
2. Keep the TAGS column and the audience fields. Decide which tags become MailerLite groups, and create the custom fields (text, number or date) before the import so your merge data lands in typed fields.
3. Load the subscribed file first. If you use the API, note that import-creation calls are limited to 5 per minute. Do not import the cleaned file at all.
4. Handle unsubscribes deliberately. MailerLite's API will not reactivate a subscriber whose status is unsubscribed, bounced or junk; those people can only come back through the app, a form or a landing page. That protects you from re-mailing opt-outs but also means a mistaken status cannot be fixed by script.
5. Rebuild each Mailchimp journey as a MailerLite automation, mapping the trigger and replacing branches with condition steps. Move transactional traffic that used Mailchimp Transactional to MailerSend or another sender.
6. Re-create the sending domain authentication in MailerLite, send to an internal group, then switch your signup forms and any API writes over.

Moving from MailerLite to Mailchimp

1. Export subscribers with their group memberships and statuses. MailerLite's statuses are active, unsubscribed, unconfirmed, bounced and junk; split the file by status so you can import one at a time.
2. Check your count against the target band before you import. The Mailchimp import guide warns that an import taking you over your plan's contact limit incurs additional charges, so dropping bounced and junk addresses first saves money.
3. In Mailchimp choose Audience, Add contacts, Import contacts, Upload a file. Match columns to audience fields (unmatched columns are not imported), and add the group-to-tag mapping at the tagging step.
4. Import one marketing status per run: the importer takes a single status at a time, so load the active people as Subscribed and the opt-outs as Unsubscribed in a separate import. Tick 'Update any existing contacts' only when you want blank cells to overwrite old data, since blank fields erase existing values.
5. Rebuild MailerLite automations as Mailchimp journeys; custom-field triggers need a replacement such as a tag set by your backend or an integration.
6. MailerLite landing pages and websites do not move with the list, so keep them live until the new forms are in place.