> 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/build-web4-apps.md).

# Build Web4 Apps

The Tonomy SDK allow applications to log in and interact with Tonomy identities. This is done through a familiar Single Sign-On (SSO) flow, like with oAuth 2.0 or OpenIdConnect.

**Integration is expected to take 10-30 minutes**

## Features

* **Single Sign-On 🔑:** Authenticate and login users via Tonomy ID
* **1-Click Free Transactions ⚡:** Secure, instant, and gasless smart contract execution. Users don't even need to leave your apps.
* **Verifiable Credentials ✅:** Use W3C-compliant signed credentials for private, off-chain verifiable data
* **Server Authentication 🔐**: Verify users with your server without trusting a centralized third-party
* **Multichain Crypto🌐:** Manage multiple cryptos with Tonomy ID
* **Multichain Web3 Transaction🌐:** Sign web3 transactions using WalletConnect or Anchor protocol
* **Passphrase Recovery 🔄**: Restore via username + 6-word passphrase
* **SDK languages🛠️:** JavaScript support for web, React Native, and Node.js

## Reference App

Checkout this React website's use of the SDK to log in with Tonomy ID and sign data and transactions here:

* Demo website: <https://demo.tonomy.io>
* Code: <https://github.com/Tonomy-Foundation/Tonomy-App-Websites/tree/master/src/demo>