Create prefilled form links

Professional and Enterprise forms have a Prefill API endpoint in Settings. Keep that URL secret: it includes the form's prefill API key. Post JSON to it and Chariform returns a signed form URL.

POST /api/forms/your-form-slug/prefill?key=...
Content-Type: application/json

{
  "fields": {
    "Email": "alex@example.org",
    "Membership type": { "value": "Gold", "mode": "locked" },
    "CRM person id": { "value": "12345", "mode": "hidden" }
  }
}

Field modes

• editable: the value is filled in and the applicant can change it. This is the default.
• locked: the value is shown but cannot be changed.
• hidden: the value is submitted but the field is not shown to applicants.

Use the exact field label or field id as the field key. Choice fields accept either the option label or the option id. If two fields have the same label, use the id. You can also send the key in an X-Chariform-API-Key header instead of the query string.

{
  "url": "https://chariform.com/f/your-form-slug?prefill=..."
}

Prefill links are signed and require Professional or Enterprise. If someone edits the link, locked and hidden values are rejected on submit.