Subscribe API

Enroll subscribers programmatically from any external site or tool. The API reuses the same double opt-in flow as the on-site form: the person still receives a confirmation email and must click to confirm, so a key can never force-confirm anyone.

Endpoint

Send a JSON POST with a bearer API key.

POST https://phluentlabs.com/api/v1/subscribe
Authorization: Bearer <your api key>
Content-Type: application/json

Create and manage keys in the admin panel under API Keys. The raw key is shown only once at creation — store it securely.

Request body

  • email (required) — the subscriber's email address.
  • firstName, lastName (optional) — name fields.
  • ref (optional) — a referral code to credit a referrer; unknown codes are ignored.
  • tags (optional) — an array of tags to apply to a brand-new subscriber (e.g. where the signup came from).

Example

curl -X POST https://phluentlabs.com/api/v1/subscribe \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "email": "reader@example.com",
    "firstName": "Ada",
    "ref": "OPTIONAL_REFERRAL_CODE",
    "tags": ["source:partner-site"]
  }'

Responses

  • 200 — { "ok": true, "alreadySubscribed": false } a confirmation email was sent (or the email was already subscribed).
  • 400 — invalid body / missing or malformed email.
  • 401 — missing or invalid API key.
  • 429 — rate limit exceeded (slow down and retry).

Prefer a no-code option? See the embeddable subscribe form.

Making sure your emails land in the inbox? See the deliverability guide.