Opt-In Submit API
Push lead data into Hermon from any external source — landing pages, funnels, Typeform submissions, webinar registrations, or custom forms — using a simple REST API.
How It Works
POST lead data to the /api/opt-in/submit endpoint with your API key. Hermon handles deduplication automatically:
✦
New lead
If no lead with that email exists in your organisation, a new lead record is created.
✦
Existing lead
If the lead already exists (matched by email), their record is updated and a new opt-in event is appended.
✦
UTM tracking
UTM parameters, referrer, and landing page URL are stored. If utm_source is present, an AI-generated source summary is queued.
✦
Setter attribution
If traffic.utm_content starts with user_ (a Clerk user ID), Hermon automatically assigns that user as the setter on the lead.
Endpoint
Method
POST
Base URL
https://api.hermon.io
Rate Limit
5 req/s per key
POSThttps://api.hermon.io/api/opt-in/submit
Authentication
The opt-in endpoint uses API key authentication — not Clerk JWT. Pass your key in the x-api-key request header:
x-api-key: sk_live_abc123...
View API key management →Lead Sources
The source field is required and must be one of:
| Value | Description |
|---|---|
| CALENDLY | Lead arrived via a Calendly booking |
| MANUAL | Lead was created manually |
| TYPEFORM | Lead submitted via a Typeform form |
| WEBINAR | Lead registered for a webinar |
| NEWSLETTER | Lead subscribed to a newsletter or email list |
| LANDING_PAGE | Lead submitted via a landing page form |
| OTHER | Any other external source |
Quick Start
API keys are hashed before storage. The full key is only shown once at generation. If you lose your key, you must regenerate it — which invalidates the old one.