April 23, 2026 · Developer Guide
Electronic Signature API for Developers: How to Choose, Integrate, and Ship in 2026
The terms "electronic signature" and "digital signature" are used interchangeably, but search results for each are very different. This guide covers both — and shows you how to integrate in 30 minutes.
Founder, Signbee
TL;DR
An electronic signature API lets you send documents for legally binding signature from your code. The fastest integration is Signbee — one endpoint, Bearer auth, 30 minutes. The most established is DocuSign — 400+ endpoints, OAuth 2.0, 1-2 days. For most developers, a simple, affordable API beats a complex enterprise platform.
Electronic signature vs digital signature: does it matter?
Legally, no. The US ESIGN Act defines an "electronic signature" as any electronic sound, symbol, or process attached to a contract. The EU eIDAS Regulation uses the same term. "Digital signature" technically refers to a specific cryptographic method (PKI-based), but in practice, every modern e-signature API uses cryptographic verification regardless of what you call it.
For developers, the distinction matters only when you need Advanced (AES) or Qualified (QES) signatures under eIDAS — which is less than 5% of use cases.
6 electronic signature APIs compared
| Provider | Endpoints | Auth | Integration | Free tier | Price |
|---|---|---|---|---|---|
| Signbee | 1 | Bearer | ~30 min | 5/mo | $0.50/doc |
| SignWell | ~15 | API key | ~2 hrs | 25/mo | $1.50/doc |
| Docuseal | ~10 | API key | ~4 hrs | ∞ (self-host) | Free / $30/mo |
| BoldSign | ~30 | API key | ~3 hrs | 100 total | $2.00/doc |
| HelloSign | ~40 | API key + OAuth | ~4 hrs | 3/mo | $4.00/doc |
| DocuSign | 400+ | OAuth 2.0 + JWT | 1-2 days | Sandbox | ~$25/env |
Integration examples in 3 languages
const res = 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\nTerms here...",
recipient_name: "Jane Smith",
recipient_email: "jane@example.com",
}),
});
const { document_id, signing_url } = await res.json();import requests
response = requests.post(
"https://signb.ee/api/v1/send",
headers={"Authorization": "Bearer YOUR_API_KEY"},
json={
"markdown": "# Service Agreement\n\nTerms here...",
"recipient_name": "Jane Smith",
"recipient_email": "jane@example.com",
},
)
data = response.json()
print(f"Signing URL: {data['signing_url']}")curl -X POST https://signb.ee/api/v1/send \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_API_KEY" \
-d '{
"markdown": "# Service Agreement\n\nTerms here...",
"recipient_name": "Jane Smith",
"recipient_email": "jane@example.com"
}'When to use an electronic signature API vs a web platform
Frequently Asked Questions
What is an electronic signature API?
A REST service that lets you send documents for legally binding e-signature from your code. It handles PDF generation, email delivery, signature capture, and certificate creation.
Is "electronic signature" the same as "digital signature"?
In practice, yes. Both terms refer to signing documents electronically. Technically, "digital signature" implies cryptographic verification, but all modern APIs use this by default.
Which electronic signature API is easiest to integrate?
Signbee — single endpoint, Bearer auth, no SDK. Integration takes approximately 30 minutes with code examples in JavaScript, Python, and cURL.
Are there free electronic signature APIs?
Yes — Signbee (5 docs/month), SignWell (25 docs/month), and Docuseal (unlimited, self-hosted). DocuSign offers a free sandbox for development only.
Start integrating — 30 minutes, one endpoint, free tier.
Last updated: April 23, 2026 · Michael Beckett is the founder of Signbee and B2bee Ltd.