# EAS

By [Once Upon](https://paragraph.com/@onceupon-2) · 2024-02-07

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Starting today, you can use Once Upon to read onchain EAS attestations.

### What is EAS?

Ethereum Attestation Service (EAS) is infrastructure for making attestations onchain or offchain about identity, asset ownership, reputation, etc. with cryptographic proofs.

You can learn more about EAS [here](https://attest.sh/).

### **Account Activity**

As of now, EAS is deployed on Ethereum, Arbitrum, Optimism, Base and Linea.

For OP Stack (Optimism) chains, EAS has the same contract address. This makes it easy to see all EAS activity across many chains for any account.

![](https://storage.googleapis.com/papyrus_images/2c1f8ad6bb286d41c68f2350378e954cc7f46d4bd1a4ea2f8114097784e43153.png)

The two contract addresses on OP Stack chains are:

*   EAS: [0x4200000000000000000000000000000000000021](https://www.onceupon.gg/0x4200000000000000000000000000000000000021)
    
*   Schema Registry: [0x4200000000000000000000000000000000000020](https://www.onceupon.gg/0x4200000000000000000000000000000000000020)
    

### **EAS Usage**

Coinbase uses EAS on Base to attest to accounts being verified Coinbase users as well as their country of residence.

![](https://storage.googleapis.com/papyrus_images/09c583c386e030ab8e974d5fc82b9c7dbdc83aac09f49f8d77255a5bb0cffa12.png)

Additionally, Farcaster uses EAS to attest to new user signups via Coinbase Wallet.

![https://warpcast.com/dwr.eth/0x9bed3dde](https://storage.googleapis.com/papyrus_images/6f4c38d4150d45cd336fb152110a478bd585996aa93cfd643bd533967e0713bb.png)

https://warpcast.com/dwr.eth/0x9bed3dde

![](https://storage.googleapis.com/papyrus_images/7aeed8238b3914329bef79373abcca30c618b0b2086dbaec8d91f52a4a40fcd1.png)

### **Give It a Try!**

This EAS feature is powered by the open-source [EVM Context](https://github.com/Once-Upon/context) library. Thanks to [datadanne.eth](https://warpcast.com/datadanne.eth) for completing the [bounty](https://warpcast.com/jomessin/0x7be3e642) to add support for EAS!

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*Originally published on [Once Upon](https://paragraph.com/@onceupon-2/eas)*