FormSMTP docs

Quickstart

1. Create an account at app.formsmtp.com. Email and password, Google or GitHub.
2. Add a project for your site and connect your SMTP account. Choose your provider (Gmail, Zoho, Outlook, SES…) and the host and port fill in. Click Test connection.
3. Copy your API key from API & code, then use the HTML form below or call the JSON API.

That's it. Every send shows up under Logs with its status and, if something fails, the exact error from your SMTP server.

HTML form endpoint

The fastest way to add a working contact form: no JavaScript, no backend. Point a regular form at your project's form URL.

<form action="https://app.formsmtp.com/api/v1/form/YOUR_API_KEY" method="POST">
  <input name="name" required>
  <input name="email" type="email" required>
  <textarea name="message" required></textarea>

  <!-- optional -->
  <input type="hidden" name="_subject" value="New message from my site">
  <input type="hidden" name="_next" value="/thanks.html">
  <input type="text" name="_gotcha" style="display:none" tabindex="-1" autocomplete="off">

  <button>Send</button>
</form>

Every field is included in the email. The message goes to you: the first address under Allowed recipients, or the project's From address. A visitor can never choose who receives it, so the key is safe in public HTML.

Send Accept: application/json (or a JSON body) to get a JSON response instead of a page, which is handy for fetch(). File uploads (multipart/form-data) aren't supported.

Send API

POST https://app.formsmtp.com/api/v1/send with your key as Authorization: Bearer <key> (or X-API-Key).

curl -X POST https://app.formsmtp.com/api/v1/send \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"to":"someone@example.com","subject":"Hello","html":"<p>It works!</p>"}'

const res = await fetch("https://app.formsmtp.com/api/v1/send", {
  method: "POST",
  headers: { Authorization: "Bearer YOUR_API_KEY", "Content-Type": "application/json" },
  body: JSON.stringify({ to: "someone@example.com", subject: "Hello", text: "It works!" }),
});
const data = await res.json(); // { success: true, messageId: "…" }

import os, requests

requests.post(
    "https://app.formsmtp.com/api/v1/send",
    headers={"Authorization": f"Bearer {os.environ['FORMSMTP_KEY']}"},
    json={"to": "someone@example.com", "subject": "Hello", "text": "It works!"},
    timeout=30,
)

Templates & variables

Design emails in the visual builder (or paste HTML) and send them by name. Use {{variable}} anywhere, with an optional fallback: {{first_name|there}}.

{
  "to": "ana@example.com",
  "template": "Welcome",
  "variables": { "first_name": "Ana", "login_url": "https://example.com/login" }
}

If the recipient is one of your contacts, their name, email and custom fields are filled in automatically, along with {{unsubscribe_url}}.

Contacts API

POST https://app.formsmtp.com/api/v1/contacts adds or updates a contact. Perfect for a newsletter or waitlist form.

await fetch("https://app.formsmtp.com/api/v1/contacts", {
  method: "POST",
  headers: { Authorization: "Bearer YOUR_API_KEY", "Content-Type": "application/json" },
  body: JSON.stringify({
    email: "ana@example.com",
    name: "Ana Silva",
    tags: ["newsletter"],
    fields: { plan: "pro" },
  }),
});

Then email a tag, everyone, or specific people from Emails: now, at a set time, or on a daily, weekly or monthly schedule. Each person gets a personal copy with a working unsubscribe link.

Keeping a public key safe

Keys used in browser code are visible to anyone, so lock them down under Settings → Security:

• Allowed websites: only these origins may call the API from a browser (for example https://yoursite.com).
• Allowed recipients: only these addresses or @domains can receive email. For a contact form, list just yourself.
• Max emails per hour: caps how much a copied key can send.

Origin checks only stop browsers. A script can fake an Origin header, which is why the recipient list and hourly limit matter most. For server-side code, leave Allowed websites empty and keep the key in an environment variable.

Responses & errors

Success: 200 {"success": true, "messageId": "…"}. Errors: {"success": false, "error": "…"} with:

SMTP settings

Common providers. The dashboard fills these in when you pick one.