E-signature API – under your own name and logo

Your brand, everywhere

• Signing page with your company name and logo.
• Emails (invitations, reminders, signed PDF) sent in your company’s name.
• Text messages with your company name as the sender.
• Signing certificate at the end of the PDF in your company’s name.

Your own branding is included in every package at no extra cost. We add your name and logo when we set you up.

Pricing: one-off packages

No monthly fee, no setup fee, no contract. You buy a package once and can use it for 24 months. When the signatures run out, you buy a new one.

One signature = one signer on one document. Email invitations, reminders, the audit trail and the signed PDF are all included.

How does the API work?

1. Your system sends the PDF and the signers (name, email, role and an optional phone number) in a single call.
2. Signer sends the invitations and reminders and returns each signer’s link.
3. Your system checks the status or fetches the signed PDF once everyone has signed.

POST https://signer.fi/api/esign/requests
    x-api-key: <your key>
    Content-Type: application/json

    {
      "documentName": "Tenancy agreement – 12 Example Street, Flat 2",
      "pdfBase64": "JVBERi0xLjcK…",
      "signers": [
        { "role": "Landlord", "name": "Anna Example", "email": "anna@example.com" },
        { "role": "Tenant", "name": "Peter Example", "email": "peter@example.com", "phone": "+447700900123" }
      ],
      "expiresInDays": 30,
      "language": "en"
    }

language sets the signers' language: fi, en, sv, da, no or et. Invitations, reminders, text messages, the signing page and the signing certificate are in that language. Without it, your company's default language is used.

• GET /api/esign/requests/{id} – status of the request and its signers
• GET /api/esign/requests/{id}/pdf – the signed PDF with its certificate

Limits: PDFs up to 10 MB, up to 10 signers per document. Encrypted PDFs are not accepted.

Security

• Every signing link is personal and unguessable (a 192-bit random token).
• An API key can only see its own company’s documents.
• All traffic is encrypted (HTTPS, TLS 1.3), and the integrity of each document is verified with a SHA-256 hash.