Electronic signature API - integrate e-signatures into your system

Integrate electronic signatures into your application, CRM, DMS, ERP, or document workflow system. Choose an integration model that fits your process – from the ready-to-use SIGNIUS interface to a fully customised UX, with the option to sign documents without them ever leaving your organisation.

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Electronic Signature API

Automate e-signing and KYC
identity verification for businesses

Support for multiple signature types:

electronic signatures (SeS)
advanced electronic signatures (AdES)
advanced electronic signatures with KYC identity verification (AdES + KYC)
personal signatures
qualified electronic signatures (QES)

With our REST API, you can:

sign documents directly within your application
automate document workflows
keep users within a single environment
maintain full control over the user experience
in some cases, keep documents within your own infrastructure

One ecosystem. Three ways to integrate.

Choose the integration model that best fits your application.
Would you prefer the ready-to-use SIGNIUS interface, or would you rather keep the entire signing process within your own application? Compare the options:

API Professional

Sign documents using the SIGNIUS platform interface

The simplest way to enable document signing in your system. Your application manages the documents and the signing process, while users complete identity verification (optional) and sign their documents through the SIGNIUS interface.

Ideal if you:

want to get e-signatures up and running quickly
need AdES and QES signatures
don’t want to build a signing UI
want to use the ready-made SIGNIUS platform, with the option to customise it with your branding

API Headless PDF

Sign PDF documents without the SIGNIUS front end

The entire user experience stays within your application. You send the PDF document to SIGNIUS and, once it has been signed, receive the completed, signed document back.

Ideal if you:

have your own application and UX
want to keep users within your own environment
need to sign PDF documents
don’t want to build the entire technical signing layer yourself

API Headless Hash

Hash signing – maximum control over your documents

Your document stays within your infrastructure. You send only its cryptographic hash to SIGNIUS, then embed the signed hash back into your document.

Ideal if you:

have your own document workflow system
cannot allow documents to leave your organisation
need full control over the user experience
have your own document and signature management layer

KYC Identity Verification API

Create a new user and verify their identity

The RA API lets you create a user and, where required by the selected signing process, verify their identity. It can be used alongside the Headless PDF and Headless Hash API models.

Discover the API documentation

What can you integrate?

Integrate electronic signatures with your business systems.

CRM – sign sales contracts electronically as part of your sales process
ERP – automate the signing of documents and contracts generated in your system
DMS (document management) – automatically send documents for signing and receive signed files
e-File and HR systems – sign employment contracts and HR documents electronically
BPM (workflow) – add electronic signatures as another step in your business processes
Your own application or platform – embed the entire signing process within your own environment
And many other platforms, systems and applications

Download the SIGNIUS API brochure

How does electronic signature API integration work?

Create a user

Use the API to create a user and, if required, start the identity verification process.

Send a document

Depending on your integration model, send either the PDF document or its hash to SIGNIUS.

Define the signing process

Specify the signers and the type of electronic signature required.

The user signs the document

The user signs the document on the SIGNIUS platform or directly within your application.

Done! Continue your workflow

Receive the signed PDF or hash, then let your system automatically move to the next step – for example, storing the document or updating the case status.

Why integrate SIGNIUS via API?

Integration in 24h

Connect SIGNIUS to your existing systems with our ready-to-use REST API – no need to build signing infrastructure from scratch. Depending on the integration model and scope, you can be up and running in as little as 24 hours.

Lower implementation costs

Compare SIGNIUS pricing with other solutions and find the right option for your business.

Custom UX

With our Headless API models, you can use your existing interface or build a fully customised signing experience directly into your application.

Flexible integration

Choose from different API models to fit your business needs.

Sandbox | risk-free testing

Test for free before going live.

Multiple signature types in one place – SeS, AdES and QES

Technical support

We help you choose the right integration model for your system architecture, document storage and UX requirements. Our team also supports you throughout the integration process.

eIDAS compliance

Enterprise-grade security and compliance with applicable legal requirements.

Who uses the SIGNIUS API?

Discover some of our customers.

Looking for an Electronic Signature API? Let’s talk!

Tell us about your process. We’ll recommend the right API model and show you how it can be integrated with your application.

Book a consultation

Are you a developer or technical specialist? Click here and explore the API documentation to see how the integration works.

Electronic signature API - integrate e-signatures into your system