SignatureAPI
Mint Starter Kit

Envelopes

Envelope branding

Add your company logo and accent colors to signing ceremonies and recipient emails

Add your company’s branding to individual envelopes to customize the signing ceremony interface and the emails sent to recipients. Each envelope can have its own branding configuration.

Branding applies to:

  • The signing ceremony interface recipients see.
  • Emails sent to recipients throughout the signing process (signing requests and completed document delivery).

Branding does not apply to:

  • Internal notification emails sent to the account owner.
  • Deliverables (signed documents).

See the Visual examples section below for screenshots.

Adding branding

Include a branding object when creating an envelope:

// POST https://api.signatureapi.com/v1/envelopes
// X-API-Key: key_test_...
// Content-Type: application/json

{
    "title": "Service Agreement",
    "documents": [
        //...
    ],
    "recipients": [
        //...
    ],
    "branding": {
        "logo": "https://api.signatureapi.com/v1/uploads/upl_3jBYlxa9gv0fGLzFAnfwxe",
        "accent_color": "#9810fa",
        "email": {
            "footer": "**Disclaimer:** This email and its attachments may contain confidential information. If you are not the intended recipient, please delete it and notify the sender.",
            "logo_position": "left"
        }
    }
}

Accent colors

The accent_color property sets the color of buttons in emails and the signing ceremony. Specify the color as a hex code (for example, #9810fa).

The accent color applies only to button styles. Other interactive elements such as text input fields, checkboxes, and signature boxes keep their default colors (blue for normal states, red for error states).

Accessibility requirements

The accent color must meet a contrast ratio of at least 4.5:1 against white, following WCAG guidelines. If the color does not meet this requirement, the API returns an error with a suggested compliant alternative.

Test your color’s contrast ratio using the WebAIM Color Contrast Checker before submitting.

Logos

The logo property sets the image displayed in the header of emails and the signing ceremony.

  1. Upload your logo to the Dashboard Library.
  2. Copy the resulting URL (it will look like https://api.signatureapi.com/v1/uploads/upl_...).
  3. Use that URL in the logo property.
Only files uploaded to your account’s Library can be used as logos. Direct external URLs are not supported.

Logo requirements

  • Format: PNG
  • Height: At least 160px to avoid pixelation on high-resolution displays
  • File size: Under 100KB
  • Background: Transparent works best, as logos appear against both white (emails) and gray (ceremony) backgrounds

Email customization

Use the email object within branding for additional email customization.

The footer property adds content at the bottom of all recipient emails, after SignatureAPI’s standard footer. Use it for legal disclaimers, privacy notices, or contact information.

The footer supports a subset of Markdown: **bold**, *italic*, and \n\n for paragraph breaks.

Logo position

The logo_position property controls the horizontal alignment of the logo in email headers. Accepted values are left, center, and right. The default is left.

Visual examples

The following screenshots show branding applied to a purple (#9810fa) envelope with a left-positioned logo.

Signature request email

Signature request email with custom branding applied

Signing ceremony interface

Signing ceremony interface with custom branding applied

Completed document delivery email

Document delivery email with custom branding applied