> For the complete documentation index, see [llms.txt](https://docs.tonomy.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tonomy.io/introduction/features.md).

# Features

### **Passwordless Single Sign-On (SSO)** 🔑

Users log in via Tonomy ID (like Google SSO but without third-party control).

**Why use it?**

* Easy onboarding for users
* Privacy-first: **No big tech**, **No centralized databases**

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### ️**Sovereign Digital Signatures** ✍

Turn a user's phone into an authenticator for:

* **W3C Verifiable Credentials**
* **Documents (PDFs)**

**Why use it?**

* **Non-repudiation**: Proof that **only the user** signed it
* **Compliance-ready**: Supports **eIDAS** and **qualified electronic signatures** (coming soon).
* **Secure approvals**: Optional **multi-factor authentication (MFA)** for high-value operations.

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### **Server Authentication** 🔐

Securely **authenticate users to your backend server**

**Why use it?**

* **Verify every request**: **Cryptographic proof** that **each request is user-authorized**.
* **No password dependencies**: Avoid risks tied to **database breaches**.
* **Non-repudiation**: Logs become **cryptographically verifiable** (proof the user initiated the action).

***

### **Sovereign Data Vault** 🗄️

Store user data locally (e.g., KYC, preferences), enabling:

* **Secure data storage** on user devices
* **Cross-app data sharing** with **user consent**

**Why use it?**

* Reduce onboarding friction (e.g., pre-fill user forms)
* **Compliance**: Built-in **privacy** and **GDPR alignment**.
* **Eliminate custody risks**: Apps **don’t need to hold sensitive user data**.

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### **Smart Contract Transactions** 🌐

Enable **Seamless Web3 transactions**, signed securely by users.

**Why use it?**

* **Gasless, seamless UX**: Users can **execute transactions without leaving your app**.
* **Flexible signing**: Supports **smart contract actions**, **DAO votes**, and **token transfers**.
* **Optional MFA**: Increase security for **high-value actions**.
* **Performance**: Built on **Antelope’s scaleable protocol** (0.5s block times, high TPS).

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### **Peer-to-Peer Messaging** 📩

DIDComm-based **end-to-end encrypted messaging** between users across apps.

**Why use it?**

* **User privacy by default**
* **Cross-app interoperability**