# Account upgrade

## Universal cross-chain addresses

Ether.fi has, since the launch of ether.fi Cash, provided a cross-chain deposit service utilising universal addresses. Within this architecture, each user is assigned a universally consistent address across multiple EVM-compatible blockchains ('top-up' chains). One of these addresses is designated the 'core' chain, and any supported assets deposited on any of the supported top-up chains are transparently bridged to the core chain. Refer to our [technical documentation](https://etherfi.gitbook.io/etherfi/cash/technical-documentation#id-2.-effortless-cross-chain-via-universal-address) for more information.

The core chain is the network that holds user assets after bridging, and is the network on which all card payments are settled, and on which swaps and other actions take place.

## Account upgrade process

The account upgrade process leverages the existing cross-chain address architecture. For each existing user safe on the current core chain, a safe is deployed on the new core chain (Optimism), and a migrate function is called. This results in the cross-chain deposit service treating the previous core chain as a top-up chain.

### Addition of a new core chain

The upgrade process is driven by the addition of a new core chain, and switching the existing core chain to be a supported top-up chain. Throughout the upgrade, all assets exist on the universal safe address, or in the bridges used.

<figure><img src="https://1029745181-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FG3Lk76lfvw9ecPIg0mK8%2Fuploads%2FvHue8LhNRj3bp6ekndif%2FScreenshot%202026-04-02%20at%2018.22.20.png?alt=media&#x26;token=ad44be8a-6f14-4ea3-a350-f47e58f2f12a" alt=""><figcaption></figcaption></figure>

The following existing bridges are used, and live on-chain tracking is available for all:

* Layer zero
* Stargate
* Canonical L2 bridges

The end result is that all assets arrive on the new core chain, and all current functionality and custody behave exactly the same.

## Full multi-chain vault support

This upgrade, which allows switching of core chains, sets the groundwork for enabling a fully non-custodial chain-agnostic vault system where users can arbitrarily bridge assets between multiple core networks to enable native DeFi integrations. An example of this would be a HyperLiquid trading integration where user assets can exist across 2 networks concurrently and be used for card spending or trading within the same non-custodial architecture.

Multi-chain vault support will be a future upgrade.