# Quick start guide
Learn how to authenticate your users in just a few steps. You can use the Authentication API both to onboard new users and to authenticate registered users. See our API reference for detailed information about all the available endpoints and properties.
# Before you start
If you don't have an account already, you need to create a free Signicat account (opens new window).
# About the integration options
You can integrate with Signicat in two ways, either by connecting to our REST API, or by using OpenID Connect.
# Signicat Express REST API
Our REST API gives you a lot of flexibility and enables options such as headless authentication.
- Headless authentication
- Native mobile app experience for some methods
- Iframe support
- Signicat Express SDKs
# Learn more
# OpenID Connect (OIDC)
Integrate with Signicat through the industry standard for authentication.
- Industry standard being used by some of the biggest players in technology such as Google and Facebook
- Easily available libraries for different languages and frameworks
- End user consent
- No need to manage user sessions on your own