Sendly compared with the alternatives
Honest comparisons between Sendly and the email providers people move from, plus which of them Sendly can accept a send from without a rewrite.
How to read these pages
Comparison pages written by a vendor are usually worth exactly nothing, because the vendor picks the axes. These try to be worth something by following two rules.
First, everything asserted about Sendly is checkable against the product today — the price curve, the free cap, which provider dialects the API accepts, what the MCP server exposes. Nothing is described as shipping soon.
Second, nothing is asserted about anyone else's prices, limits or roadmap. Those change without telling us, and a stale claim about a competitor is the one thing on a page like this you can catch us being wrong about. Where a real comparison would help, each page gives you the question to ask their documentation instead of an answer that expires.
Each page also says plainly what Sendly does not do. If that is the part you needed, you will find it faster here than three weeks into a migration.
The comparisons
| Compared with | In one line | Keeps your existing SDK? |
|---|---|---|
| Sendly vs Resend | A transactional email API. Sendly is that plus campaigns, workflows and inbound mail. | Yes — base URL and key |
| Sendly vs SendGrid | The incumbent. Sendly is a smaller surface with one metered price per email. | Yes — base URL and key |
| Sendly vs Mailchimp | A marketing suite operated from a dashboard. Sendly is operated from an API. | No — import and rebuild |
| Sendly vs Customer.io | Multi-channel messaging. Sendly does the email channel of that job and nothing else. | No — import and rebuild |
| Sendly vs Mailgun | An email API with deliverability tooling. Sendly adds the marketing half. | Yes — base URL and key |
Five providers Sendly can accept a send from as-is
Sendly implements the transactional-send dialect of five providers on dedicated endpoints. If you send through one of them, moving is a base URL and an API key: the vendor SDK you already run keeps working, and your call sites do not change.
- Resend — Set baseUrl on the Resend client, or the RESEND_BASE_URL variable.
- SendGrid — Set the base URL on @sendgrid/client after setApiKey, which resets it.
- Postmark — Override the request host on the Postmark client.
- Mailgun — Pass url on the mailgun.js client, with basic auth as api:<key>.
- Plunk — Sendly's ancestral API — the closest thing to a drop-in replacement.
The compat endpoints cover the transactional send path only. Contacts, campaigns, workflows, templates and webhooks are the native API's job, and the official SDKs cover all of it.
Everything else — Mailchimp, Customer.io, Klaviyo, Brevo, anything else with a contact list — moves as data: export your contacts and your unsubscribes, import both, verify a domain, rebuild the templates you still use. The migration guides have the technical detail.
What Sendly does
Sendly is one workspace for transactional email, marketing campaigns and automation, against one contact database. Everything below is in the product today, not on a roadmap.
| Area | What you get |
|---|---|
| Transactional send | REST API with idempotent sends, batch send, scheduling and cancellation, template variables, attachments, and a delivery record you can read back. |
| Campaigns | One-off broadcasts to a list or a segment, with scheduling, pause and resume, and per-campaign stats. |
| Workflows | A visual builder for automated sequences, with branching on contact data and on tracked events. Runs server-side, with an execution log per contact. |
| Contacts and segments | Custom fields, CSV import, and dynamic segments that re-evaluate from contact data and behaviour. Built for millions of rows, with cursor pagination throughout. |
| Deliverability | Domain verification with guided DNS setup that publishes the records for you and then watches them for drift. SPF, DKIM and DMARC alignment, suppression list, bounce and complaint handling. |
| Inbound | Real mailboxes on your own domain, reachable over IMAP and SMTP, with the messages also projected into the API. |
| Events and webhooks | An event stream you can query and subscribe to, signed webhook deliveries with retries, and tracked custom events that can trigger a workflow. |
| AI agents | A remote MCP server, so an agent can work in your account under permissions you tick yourself. Irreversible ones are never granted by default. |
| SDKs | Official open-source clients for JavaScript and Python, both at 1.0.0, generated from the published OpenAPI contract. |
| Self-hosting | Documented Docker deployment, if you would rather run it yourself. |
What Sendly costs
There is no monthly platform fee and there is no plan to outgrow. A free tier, metered usage that gets cheaper as volume rises, and a conversation for anything past that.
| Plan | Price | What it is |
|---|---|---|
| Free | $0 / month · forever | Everything you need to get started. No credit card required. 5,000 emails / month · Transactional, campaigns & workflows · Full REST API, SDKs & webhooks · Powered-by-Sendly badge on sent email |
| Pay as you go | $1.00 / 1,000 emails | Volume pricing that drops as you send more. No monthly fee and no plan to outgrow. $1.00 per 1,000 emails up to 50,000 · $0.70 per 1,000 above 50,000 · $0.50 per 1,000 above 250,000 · Badge removed from your email · Set your own limit per category · Billed in USD, EUR or GBP |
| Custom | Let's talk tailored to your volume | High-volume or regulated sending that needs limits set by a human. Everything in Pay as you go · Custom sending limits · Higher daily throughput · Direct support from the team |
The free tier is a real tier, not a trial: it does not expire, and nothing about it is time-limited. Its allowance is shared across transactional sends, campaigns, workflows and inbound mail, because Sendly meters emails rather than products.
Questions people ask
- Which providers can Sendly accept a send from without code changes?
- Resend, SendGrid, Postmark, Mailgun and Plunk. Each has a dedicated compat endpoint that parses that vendor's transactional-send request shape, so the vendor SDK you already run keeps working once you change its base URL and its key.
- Is the compat endpoint a second-class path?
- No. It translates the request and then runs the same pipeline a native send runs, so verified-domain checks, sending limits, suppression and billing all apply identically. What it is not is a full mirror of the vendor's product: it covers the transactional send path, not their contacts or campaign APIs.
- What does Sendly cost?
- There is no monthly platform fee. The plans are: Free, $0 / month · forever; Pay as you go, $1.00 / 1,000 emails; Custom, Let's talk tailored to your volume. Contacts stored are not billed and neither are tracked events, so a large list you mail rarely costs what you actually send.
- Can I run Sendly alongside my current provider?
- Yes, and for anything with production volume it is the sensible way to start. Point one service or one environment at Sendly, watch the delivery data, and move the rest when you are satisfied. There is no cutover event and nothing about a split setup is special-cased.
- What does Sendly not do?
- It is email only — no SMS, push or in-app. There are no landing pages, forms, ads or CRM features, no standalone address-validation product, and no self-serve dedicated IP with a warm-up schedule. Each comparison page repeats the gaps that matter for the product it is about.
Something on this page out of date, or missing the case you are in? Write to support@sendly.now — we answer our own email. The full technical detail lives in the documentation.