# Bridging

OpenLedger utilizes the OP Stack Standard Bridge, deployed by AltLayer, our Rollup-as-a-Service (RaaS) partner. This ensures secure, standardized interoperability with Ethereum and aligns with the broader OP Stack ecosystem.

### **Key Highlights**

* **Non-proprietary**: The OP Stack bridge architecture (Bedrock era) is open source, audited, and used across multiple OP Stack rollups. The [OptimismPortal](https://specs.optimism.io/fault-proof/stage-one/optimism-portal.html#overview), L1StandardBridge, L2StandardBridge, and CrossDomainMessenger are canonical components. These contracts are non-proprietary and reused by projects like Base, Mode, Zora, etc.<br>
* **Custom Gas Token Bridging:** OpenLedger uses the OPEN ERC-20 token (deployed on L1) as its native gas token on L2. On the testnet, OPEN tokens are locked in the[ OptimismPortal contract on Sepolia](https://sepolia.etherscan.io/address/0x2241bdE3a85BE011BC4685D54cfE9829b5D66A5E) before being bridged. These locked tokens are then minted on L2 as part of the standard OP Stack deposit flow. While [OptimismPortal](https://specs.optimism.io/experimental/custom-gas-token.html?utm_source=chatgpt.com#optimismportal) is traditionally used for ETH deposits, OpenLedger leverages it for secure bridging of the OPEN token without altering the canonical bridge architecture.<br>
* **Secure Token Transfers**: Token bridging follows the standard OP Stack mint-and-burn model. L1 tokens are escrowed via OptimismPortal, and OPEN is minted on L2 upon deposit finalization. On withdrawal, OPEN is burned on L2 and unlocked on L1.<br>
* **Full Compatibility**: OpenLedger remains fully compatible with the standard Ethereum tooling and wallet ecosystem, including MetaMask, Ledger, Hardhat, and viem — just like any other OP Stack rollup.<br>
* **Audits & Disclosure**: The canonical bridge contracts — including the Ethereum token, L2 representations, and the bridge itself — have undergone multiple audits by firms such as OpenZeppelin and Trail of Bits. OpenLedger inherits these security guarantees, as no custom modifications were made to the underlying bridge architecture.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://openledger.gitbook.io/openledger/bridging.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.