Submit Paubox form responses via API

Paubox Forms supports a public API endpoint that accepts form responses from any system. You can use it to submit responses from a custom-embedded form, an integration with another tool, or an AI agent acting on behalf of a user.

The endpoint doesn't require an API key. You only need the form's ID, which Paubox provides in your dashboard.

What this enables

With this endpoint, you can:

Submit form responses programmatically from any system
Include file attachments alongside the response
Trigger the same secure storage, notifications, and signable workflows you'd get from a hosted Paubox form

Submissions sent through the API are stored in your Paubox account and counted toward the form's total submissions, the same as responses from a hosted form page.

Step 1: Find your form ID

Log in to your Paubox dashboard
Navigate to Paubox Forms
Open the form you want to submit responses to
Copy the form's ID from the URL

Step 2: Send a POST request

POST https://next.paubox.com/api/forms/{form_id}/submissions

The request body should include:

`form_data`, a set of key-value pairs matching the form's fields
`attachments` (optional), an array of file objects with a name and base64-encoded content

Example body:

{
"form_data": {
"first_name": "Jane",
"last_name": "Smith",
"email": "jane@example.com"
},
"attachments": [
{
"name": "consent.pdf",
"content": "JVBERi0xLjQ..."
}
]
}

The maximum request size is 250 MB, which accommodates most file uploads.

Response codes

201: submission successfully processes
400: missing or malformed `form_data` field
404: form ID not found

What happens on a successful submission

When the request returns 201:

The response is stored securely in your Paubox account
The form's submission counter increments
Any notifications you've configured fire automatically
Signable forms continue to support signature workflows

If you're building a custom-rendered form to feed into this endpoint, see Embed a Paubox form in your own website or app.

Where to find full developer documentation

Complete reference, request and response schemas, and example payloads are at docs.paubox.com/forms/submit-form.

Submit Paubox form responses via API