Digital Signature vs Electronic Signature: What Developers Actually Need to Know

The confusion is understandable

If you search "digital signature API" on Google, every result is about electronic signature APIs. DocuSign calls itself a "digital signature" platform in its meta tags but delivers electronic signatures. HelloSign markets "digital signatures" but uses the same intent-capture model. The terms have become interchangeable in marketing — but they mean fundamentally different things in cryptography and law.

As a developer integrating signing into your application, this distinction matters. Not because you need to implement PKI — you almost certainly don't — but because your stakeholders, legal team, or compliance officers might ask questions that require precise answers.

Electronic signatures: how they work

An electronic signature is any electronic process that indicates agreement. Under the US ESIGN Act, it's defined as "an electronic sound, symbol, or process, attached to or logically associated with a contract." In practice, this means:

The key element is intent. The signer must intend to sign, and the system must capture evidence of that intent. Most e-signature platforms do this by recording the signer's IP address, timestamp, user agent, and the exact document content at the time of signing.

Digital signatures: how they work

A digital signature is a specific type of electronic signature that uses public key infrastructure (PKI). The process involves three components:

When you digitally sign a document, your signing software computes a SHA-256 hash of the document content, encrypts that hash with your private key, and embeds the encrypted hash plus your certificate into the PDF. Anyone can verify the signature by decrypting the hash with your public key and comparing it to their own hash of the document. If the hashes match, the document hasn't been altered since signing.

For a deeper look at how SHA-256 certificate-based signing works under the hood, see our SHA-256 signing explainer.

The comparison that matters

What e-signature APIs actually provide

Every major e-signature API — DocuSign, HelloSign, PandaDoc, Signbee — provides electronic signatures, not PKI-based digital signatures. When DocuSign says "digital signature," they mean their click-to-sign flow with an audit trail. When you see "digital signature API" in search results, every result is an electronic signature API.

DocuSign does offer a separate "Digital Signatures" product that uses PKI, but it's an add-on for enterprise plans, requires certificate provisioning, and is used by fewer than 5% of their customers (according to their own documentation).

Signbee's approach: electronic signature with cryptographic audit trail

Signbee provides electronic signatures with a comprehensive audit trail that gives you tamper evidence without the complexity of PKI certificate management. Every signed document records:

{
  "audit_trail": {
    "document_hash": "sha256:a1b2c3d4e5f6...",
    "events": [
      {
        "event": "document.sent",
        "timestamp": "2026-05-09T10:00:00Z",
        "actor": "sender@company.com"
      },
      {
        "event": "document.viewed",
        "timestamp": "2026-05-09T10:05:00Z",
        "ip": "203.0.113.42",
        "user_agent": "Mozilla/5.0..."
      },
      {
        "event": "document.signed",
        "timestamp": "2026-05-09T10:07:30Z",
        "ip": "203.0.113.42",
        "user_agent": "Mozilla/5.0...",
        "signature_hash": "sha256:f6e5d4c3b2a1..."
      }
    ]
  }
}

This audit trail is legally sufficient for all documents covered by ESIGN, UETA, eIDAS (SES and AES levels), and the UK Electronic Communications Act. The SHA-256 hash provides tamper detection — if anyone modifies the PDF after signing, the hash won't match.

Sending a document for electronic signature

Here's what the actual API call looks like. One endpoint, one request, one response. The entire signing flow — document generation, email delivery, signature capture, audit trail, and PDF storage — happens on Signbee's side:

const response = await fetch("https://signb.ee/api/v1/send", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "Authorization": "Bearer YOUR_API_KEY",
  },
  body: JSON.stringify({
    markdown: "# Service Agreement\n\n**Provider:** Acme Corp\n**Client:** Jane Smith\n\nTerms and conditions here...",
    recipient_name: "Jane Smith",
    recipient_email: "jane@example.com",
  }),
});

const { document_id, signing_url } = await response.json();
// document_id: "doc_abc123"
// signing_url: "https://signb.ee/sign/doc_abc123"

No certificate provisioning. No CA enrollment. No key management. The electronic signature is captured when the recipient clicks the signing link, and the audit trail is generated automatically. For a complete walkthrough, see the API documentation.

When you actually need PKI

In my experience building Signbee, fewer than 1% of developers asking about "digital signatures" actually need PKI. Here are the specific cases where you do:

If your use case involves NDAs, employment contracts, SaaS terms, consulting agreements, freelance contracts, or any standard commercial document — electronic signatures are legally sufficient and dramatically simpler to implement. For a comprehensive guide to e-signature legality across jurisdictions, see our ESIGN, eIDAS, and ECA compliance guide.

The eIDAS three-tier model

The EU's eIDAS regulation defines three levels of electronic signature. Understanding these helps you answer the "is it legally binding?" question from your compliance team:

Signbee operates at the AES (Advanced Electronic Signature) level — the signer is uniquely identified via email, the signature is linked to the document via SHA-256 hash, and any alteration after signing is detectable. This satisfies the requirements for the vast majority of commercial and employment documents across all EU member states. For a deeper exploration of AES and QES requirements, read our AES/QES technical guide.

Frequently Asked Questions

Last updated: May 9, 2026 · Michael Beckett is the founder of Signbee and B2bee Ltd.