For AI-native apps and agents
Your app calls a REST API. Your agent connects over MCP and can authenticate a domain, send a campaign and check deliverability on its own. Transactional and marketing through one European pipe — with the guardrails that stop an unattended sender from destroying your domain reputation.
Free tier: 50 emails/day, transactional, no credit card. Sign-in by email link — no password.
Don't take our word for it — ask Claude, ChatGPT or Gemini to read the docs and compare us with Postmark, Resend and Brevo.
Every template is public JSON behind an open endpoint — no key, no signup, no rate limit. Hand the URL to your own model right now and let it browse, pick and adapt them; they are indexed for machines, not just for humans. Yours to use whether or not you ever send through us.
# browse the whole library curl https://charlieai.co/api/templates/ # one template, full HTML curl https://charlieai.co/api/templates/<id>
An agent sending at 3am has no judgement about deliverability. So the platform has it instead — these are enforced, not advisory.
Three DNS records before the first email leaves. No fallback, no "send anyway" flag — an unauthenticated domain is the fastest way into spam folders.
Unsubscribes, hard bounces and complaints are enforced on every path, transactional included. You cannot mail a dead address twice.
RFC 8058 one-click plus a visible link, added per recipient on marketing sends. Gmail and Yahoo require it; you don't have to remember it.
New senders ramp automatically and start on probation pools, so one careless neighbour can never spend your reputation.
The API for your code. MCP for whatever model you already work in.
# your app curl -X POST https://charlieai.co/ext/v1/transactional \ -H "Authorization: Bearer $CHARLIE_API_KEY" \ -H "Content-Type: application/json" \ -d '{"to_email":"user@example.com", "subject":"Welcome", "html":"<p>Thanks for signing up.</p>"}' # your agent — add this MCP endpoint to Claude, ChatGPT or Gemini https://charlieai.co/mcp
Contacts, campaigns, per-recipient personalised marketing, suppression checks and domain verification are all available through both. Full reference in the documentation.
EU data residency on infrastructure we own and operate — not resold capacity. No tracking pixels and no rewritten links, which means two things at once: your mail looks like a letter rather than a campaign to inbox providers, and there is no behavioural data to leak, minimise or explain. GDPR and ePrivacy by construction rather than by settings page.
Charlie OÜ, Tallinn. Sending from our own fleet in the EU.
No per-contact fees, no charges for addresses you store and never email.
| Plan | Volume | Price | |
|---|---|---|---|
| Free transactional only |
50/day ~1,500/month |
€0 | Sign up |
| Dev marketing unlocked |
20,000/month | €19 | Start 14-day trial |
| Startup | 50,000/month | €49 | Start 14-day trial |
| Above that | quoted per case | — | Book 15 min · email |
Paid plans include a 14-day trial. Cancel any time — your key keeps working on the free tier, so nothing in your app breaks the day a subscription ends.
If you build apps or marketing tooling for other companies, you can put Charlie underneath and keep the customer relationship. The mail already leaves from your client's own authenticated domain, so nothing in their inbox says Charlie — and the unsubscribe page can point at your URL too.
Each client gets their own workspace, their own verified domain and their own reputation, so one careless sender can never spend another's. We invoice you once; you price your clients however you like. Partner rates start at three client workspaces.
Tell us what you're building: book 15 minutes or email hello@charlieai.co.
Then this is the wrong door, and the plans on this page do not cover Shopify stores — a workspace with a connected store is refused automatically, because Shopify merchants are billed through Shopify.
The Shopify app is in review and launches in September. It gives you the whole marketing platform — pop-ups, flows, campaign previews, brand extraction and revenue attribution from your store data. See charlieai.co →