Retransmit vs useSend
Retransmit and useSend are both open source email platforms built on Amazon SES. useSend adds a full marketing suite. Retransmit stays transactional and adds prepaid billing you can fund without a card.
By the Retransmit team. Last updated .
Retransmit builds one of the products compared here. Every competitor number was checked on the vendor's own site on the date above, and nothing on this page is paid placement.
These two are the closest pair in this comparison series. Both are open source, both self-host, and both send through Amazon SES under the hood. The differences are focus and billing. useSend, formerly Unsend, bundles marketing campaigns, a contact CRM, an email editor, and SMTP alongside its API, and bills usage monthly with a $10 minimum. Retransmit ships a smaller transactional core with batch sending and signed webhooks, and its cloud runs on prepaid credits with local payment methods.
At a glance
Both projects believe you should be able to read and run your email stack. They differ on how much product sits on top of SES.
| Retransmit | useSend | |
|---|---|---|
| Positioning | Transactional email API, cloud or self-hosted | Open source email platform for product, transactional, and marketing email |
| Source code | AGPL-3.0 on GitHub, MIT licensed SDK | AGPL-3.0 on GitHub |
| Self-hosting | Yes, free | Yes, Docker and Railway guides |
| Underlying infrastructure | Amazon SES | Amazon SES, stated openly |
| Free cloud tier | Prepaid credits, pay per send | 3,000 emails a month, 100 a day, 1 domain, 1 seat |
| Paid model | Prepaid balance, no minimum | $10 a month minimum usage |
| Best fit | Transactional sending with batching and webhooks | Product plus marketing email against one contact list |
Sources: useSend
Pricing
useSend prices per email with a $10 monthly minimum: $0.40 per 1,000 transactional emails and $1.00 per 1,000 marketing emails, with unlimited domains, seats, and contact books on paid. Its free tier covers 3,000 emails a month on one domain with one seat.
Retransmit's cloud is a prepaid balance with no monthly minimum. Fund it by bank transfer or mobile money in your local currency, and it only moves when a message sends. Self-hosting either product is free.
| Retransmit | useSend | |
|---|---|---|
| Free tier | Self-hosted, every feature | 3,000 emails a month, 100 a day, 1 domain |
| Monthly minimum | None, prepaid credits | $10 of usage a month on paid |
| Transactional price | Prepaid, pay per send | $0.40 per 1,000 emails |
| Marketing price | Not offered yet | $1.00 per 1,000 emails |
| Contacts | No contact storage, nothing to pay for | Free, unlimited contacts on paid plans |
| Payment methods | Bank transfer, mobile money, local currency | Card |
Sources: useSend
Feature comparison
useSend has the wider product: campaigns, a Notion-style editor, contact books with consent tracking, SMTP, and scheduling. Retransmit counters with a bigger batch API and a heavier webhook system.
| Feature | Retransmit | useSend |
|---|---|---|
| Transactional API | Yes | Yes |
| Batch sending | Yes, 10,000 per request with per-status counts | Yes |
| Scheduled sending | Not yet | Yes, with update and cancel |
| Marketing campaigns | Not yet | Yes |
| Email editor | Not yet | Yes, WYSIWYG |
| Contact management | Not yet | Yes, books, lists, consent |
| SMTP relay | Not yet | Yes |
| Automations | Not yet | No |
| Inbound email | Not yet | No |
| SDKs | Node.js, plus REST | TypeScript, Python, Go, PHP |
| Webhooks | 9 event types, HMAC signed, 8 retries | Yes, account event webhooks |
| Analytics | Per-email logs and event history | Dashboard with opens, clicks, bounces, exports |
Self-hosting
Both stacks self-host, both bring your own SES credentials, and both keep the dashboard when you do. Both are AGPL-3.0, which requires you to publish modifications if you offer the software over a network. Retransmit's SDK is MIT on its own, so client code embeds it without restrictions.
Practically: useSend has more moving parts to run because it is more product. Retransmit is a smaller deployment, and switching between its cloud and your own instance is a base URL change in the SDK.
Which one should you pick
- Pick useSend if you want marketing campaigns, contacts, and transactional email in one open source tool.
- Pick useSend if you need SMTP today, for example with Supabase auth emails.
- Pick Retransmit if your workload is API-driven transactional sending and you want the stronger batch and webhook story.
- Pick Retransmit if prepaid credits and local payment methods fit you better than a monthly usage bill on a card.
Both are open. One is smaller. If your email is transactional, try the stack built for exactly that.
Related resources
Open source email API comparison
Retransmit, useSend, and Plunk, side by side.
Retransmit vs Plunk
Transactional focus against an all-in-one marketing platform.
Retransmit quickstart
Verify a domain, grab an API key, and send your first email in under five minutes.
Webhook docs
Nine event types, HMAC-SHA256 signatures, and a five line verification example.
Questions people ask
Are Retransmit and useSend both built on Amazon SES?
Yes. useSend says so on its homepage, and Retransmit sends through SES in the cloud and with your own SES credentials when self-hosted. Both add queuing, domain verification, logs, and webhooks on top of the raw SES API.
What does useSend cost?
As of September 1, 2026, useSend's cloud is free for 3,000 emails a month, then usage-priced with a $10 monthly minimum: $0.40 per 1,000 transactional emails and $1.00 per 1,000 marketing emails. Self-hosting is free.
Which is easier to self-host?
Both ship Docker-based setups and documented guides. Retransmit is a smaller surface, one repository with API, dashboard, queue, and SDK. useSend carries more product, including campaigns and contacts, so there is more to operate.
Does Retransmit have a contact list or campaign tool like useSend?
No. Retransmit is transactional-first and does not store contacts or send campaigns yet. If marketing email is a hard requirement today, useSend or Plunk fit better.