eSignature APIfor Developers
Add legally binding electronic signatures to your app in minutes. REST API, real-time webhooks, embedded signing, and SDKs - everything you need without building it yourself.
Plans from $6/mo · Cancel anytime
REST
OpenAPI spec
ESIGN
& UETA compliant
256-bit
AES encryption
99.9%
Uptime SLA
Send your first signed document in under 10 minutes
Three API calls: create an envelope, add a recipient with field placement, send. The rest - email delivery, signing UI, audit trail - is handled automatically.
- Full OpenAPI 3.0 specification
- Idempotent requests with envelope IDs
- Webhook events for every status change
- Download signed PDFs at any time
import SignThem from '@signthem/sdk';
const client = new SignThem(process.env.SIGNTHEM_API_KEY!);
// 1. Create envelope and attach a PDF
const envelope = await client.envelopes.create({
name: 'Service Agreement',
documents: [
{ url: 'https://yourapp.com/contracts/agreement.pdf' }
],
});
// 2. Add a recipient with a signature field
await client.envelopes.addRecipient(envelope.id, {
email: '[email protected]',
name: 'Jane Smith',
fields: [
{ type: 'signature', page: 1, x: 100, y: 600 },
{ type: 'date', page: 1, x: 300, y: 600 },
],
});
// 3. Send - recipient gets an email with a signing link
await client.envelopes.send(envelope.id);
console.log('Sent! Envelope ID:', envelope.id);How the API works
Four steps from PDF to signed document - fully automated.
Upload PDF
POST a document URL or base64-encoded file to create an envelope.
Add recipients
Specify email, name, and where signature fields should appear on the page.
Configure fields
Place signature, date, initials, or text fields with x/y coordinates per page.
Send for signing
One API call sends notification emails. Track status via webhooks or polling.
Full-featured e-signature API
Everything your application needs - from simple document signing to embedded workflows and bulk campaigns.
REST API
Full OpenAPI spec. JSON responses, predictable URLs, standard HTTP verbs. Create envelopes, manage recipients, and download signed PDFs programmatically.
Webhooks
Real-time HTTP callbacks for every signing event - envelope.sent, envelope.signed, envelope.completed, and more. HMAC-SHA256 verified, automatic retries.
Templates
Define reusable document templates with pre-placed fields. Instantiate them via API to send consistent contracts at scale without manual setup each time.
Embedded Signing
Render the signing experience inside your app via an iframe. Keep users in your product - no redirect to a third-party site. Fully white-label capable.
Bulk Send
Send the same document to hundreds of recipients in a single API call. Each recipient gets their own unique signing link. Ideal for HR onboarding and compliance.
Audit Trail
Every signing event - view, sign, decline - is logged with timestamp, IP address, and user-agent. Tamper-evident records ready for legal and compliance review.
Official SDKs
The Node.js SDK is available now on npm. Python, C#, and Java are in active development - join the waitlist to get early access.
npm i @signthem/sdkpip install signthemComing soondotnet add package SignThemComing soonMaven / GradleComing soon# Install the SDK
npm install @signthem/sdk
# Set your API key (from /app/settings/api-keys)
export SIGNTHEM_API_KEY="sk_live_..."
# Test authentication
npx signthem whoami
# → { accountId: "acct_...", plan: "starter" }Built for compliance
Every signed document is legally binding and audit-ready out of the box.
TLS 1.3 + AES-256
All data encrypted in transit and at rest.
HMAC webhooks
Every callback signed with SHA-256 for verification.
ESIGN & UETA
Signatures are legally binding in all 50 US states.
Tamper-evident logs
Immutable audit trail with timestamps and IPs.
Simple, predictable pricing
All plans include full API access. No hidden per-API-call fees.
Starter
$6/mo
Cancel anytime
- 25 envelopes/month
- Full API access
- Webhooks + templates
- Audit trail
- Email support
Pro
$14/mo
Most popular for developers
- 100 envelopes/month
- Embedded signing
- Bulk send
- Custom branding
- Priority support
Need higher volume? View all plans or compare with DocuSign.
Ready to integrate e-signatures?
Create an account, grab your API key, and send your first signed document in minutes.