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Most buyers should pick MailerSend.
MailerSend is a hosted messaging API for email, SMS, and WhatsApp, with a free tier and SDKs for more languages. Mailchimp Transactional Email is a hosted email and SMS service that sends through a JSON REST API or SMTP, but requires an active Mailchimp Standard or Premium account. We’d pick MailerSend for a free starting point or WhatsApp delivery. Choose Mailchimp when your team already uses Mailchimp and wants transactional messages alongside its app integrations.
01Side by side
| Mailchimp Transactional Email | MailerSend | |
|---|---|---|
| Pricing model | Monthly blocks of 25,000 emails; rates fall at higher volumes. | Monthly plans, with paid extra-email rates on some tiers. |
| Free tier | Demo: 500 test sends to verified domains. | Free plan: 500 emails per month. |
| API and SDKs | JSON REST API, SMTP; Node.js, Python, PHP, Ruby. | API, SMTP; cURL, Node.js, PHP, Laravel, Python, Ruby, Go, Java. |
| Integrations | Mailchimp directory has more than 300 app integrations. | MCP connections for Claude, VSCode, Cursor, and ChatGPT. |
| Deployment model | Cloud delivery service managed through web dashboard. | Hosted messaging service with web app. |
| Platforms | Web dashboard; HTTPS and SMTP work across languages. | Web app; SDKs cover eight listed languages. |
| Limits and scaling | Blocks cover 25,000 emails each; unused sends expire. | Plan quotas include 500 to 50,000 emails monthly. |
| Messaging channels | Transactional email and SMS. | Transactional email, SMS, and WhatsApp. |
Mailchimp Transactional Email Choose Mailchimp Transactional Email if
- Choose Mailchimp Transactional Email if you already pay for Standard or Premium.
- Choose it if you need JSON REST API and SMTP sending.
- Choose it if Mailchimp’s app directory fits your existing stack.
MailerSend Choose MailerSend if
- Choose MailerSend if you want a free 500-email monthly plan.
- Choose it if your app needs WhatsApp messaging.
- Choose it if you need SDKs for Go or Java.
02Pricing at real usage
MailerSend has a free plan with 500 emails per month. Its Hobby plan includes 5,000 emails monthly and costs $7 per month, or $5.60 monthly with yearly billing. Extra emails cost $1.50 per 1,000 on Hobby and $1.30 per 1,000 on Starter and Professional. The pricing page lists Starter and Professional allowances but not their plan prices.
Mailchimp Transactional Email offers up to 500 demo sends to verified domains. Paid sending is billed in monthly blocks of 25,000 emails: the first tier lists $20 per block, with per-block rates falling to $10 at 161 or more blocks. Unused sends do not roll over; sending stops at the limit unless blocks auto-purchase. Mailchimp also requires an active Standard or Premium account. Dedicated IPs cost $29.95 monthly.
03API, SDKs and integration
Mailchimp Transactional Email sends through a JSON-based REST API or SMTP relay, with custom SMTP headers. It supports dynamic templates using Handlebars or Mailchimp merge tags, and can import designs from a linked Mailchimp account. Its official client libraries are for Node.js, Python, PHP, and Ruby. The service also supports inbound email parsing and webhooks for sends, opens, clicks, bounces, spam complaints, and rejections. Mailchimp says its directory has more than 300 app integrations.
MailerSend offers API and SMTP sending, webhooks, and libraries for cURL, Node.js, PHP, Laravel, Python, Ruby, Go, and Java. Its listed MCP connections include Claude, VSCode, Cursor, and ChatGPT. The product supports email verification through its API or app, in bulk or in real time. Its homepage links to documentation, but the published SDK list does not name a CLI. For either service, SMTP offers a standard integration path; webhook events can connect delivery activity to application workflows.
04Open source, self-hosting and lock-in
Neither vendor publishes an open-source licence or self-hosted edition for these services; both are presented as hosted messaging products. Mailchimp Transactional Email sends over HTTPS or SMTP, and MailerSend supports API or SMTP sending. Those protocols give applications a familiar way to submit messages, but they do not make provider-specific templates, event handling, account settings, or reporting automatically portable.
The vendors do not publish a data-export path for moving message history and configuration between services. Before adopting either, ask how to export logs, templates, suppression data, and account settings, and confirm what happens to that data after account closure. Keep message templates and recipient state in your own systems where practical, and isolate provider-specific API calls behind an internal interface. That reduces migration work if you change delivery providers.
Questions people ask
Which service is cheaper for low-volume sending?
MailerSend has a free plan with 500 emails per month and a Hobby plan with 5,000 emails for $7 monthly, or $5.60 with yearly billing. Mailchimp’s free demo is limited to 500 test sends to verified domains; paid sending starts at $20 per 25,000-email block and requires Standard or Premium.
Does Mailchimp Transactional Email require a Mailchimp account?
Yes. Mailchimp Transactional Email is a paid add-on for active Mailchimp Standard or Premium accounts. Its demo mode allows up to 500 test emails to verified domains, but it is not a general free sending plan.
Can MailerSend send WhatsApp messages?
Yes. MailerSend offers transactional WhatsApp messaging through the WhatsApp Business API. Its pricing page does not publish a WhatsApp price, so confirm the current cost with the vendor before estimating spend.
Can either service be self-hosted?
Neither service is presented as a self-hosted product; both are hosted messaging services. If self-hosting is a requirement, ask each vendor about deployment options before integrating. MailerSend and Mailchimp Transactional Email both offer API or SMTP sending from your application.