# FAQs

# TL;DR

# What is Optimistic Ethereum?

Optimistic Ethereum is an EVM (opens new window)-compatible Optimistic Rollup (opens new window) chain. It's designed to be fast, simple, and secure.

# Where can I find more information about Optimistic Ethereum?

The most up-to-date information about Optimistic Ethereum can always be found on the Optimism Community Hub. There you'll find stuff like docs, tutorials, and collections of videos related to Optimistic Ethereum. If you're unable to find what you're looking for there, feel free to make an issue over on GitHub (opens new window).

# Using Optimistic Ethereum

# How do I connect my wallet to Optimistic Ethereum?

With the introduction of the wallet_addEthereumChain (opens new window) RPC method, many wallets now allow applications to trigger a popup to switch between networks. If your wallet supports this feature then you will be automatically prompted to switch networks when an application wants to utilize an Optimistic Ethereum network.

If your wallet does not support this feature, you will have to connect manually. The exact process for connecting your wallet to an Optimistic Ethereum network depends on the specific wallet software you're using. We've provided connection walkthroughs for the following wallets:

# How do I move assets into or out of Optimistic Ethereum?

The easiest way to move assets into or out of an Optimistic Ethereum network is to use Optimism's Gateway application (opens new window). We've written a detailed walkthrough that explains how to use the Gateway.

# Why do I need to wait a week when moving assets out of Optimistic Ethereum?

Users are required to wait for a period of one week when moving assets out of the Optimistic Ethereum mainnet. This period of time is called the Challenge Period and serves to help secure the assets stored on an Optimistic Ethereum network. You can find more information about the Challenge Period here (opens new window). Please note that the Optimistic Kovan testnet (opens new window) has a Challenge Period of only 60 seconds to simplify the development process.

# Can I change the gas price or gas limit of my Optimistic Ethereum transactions in MetaMask?

NO!! The gas price must be set to 0.015 gwei or else your transaction will fail. You also should not change the gas limit. The gas limit encodes multiple values and should never be set manually in your wallet.

More information on how to pay fees in Optimistic Ethereum can be found on this notion document (opens new window).

# Can I cancel a withdrawal after it has been submitted?

No, withdrawals currently cannot be cancelled once submitted. We are exploring this as a future system feature.

# Are there transaction fees on Optimistic Ethereum?

Yes, users are required to pay fees when sending transactions on an Optimistic Ethereum (just like on Ethereum). However, these fees are greatly reduced when compared to Ethereum. Refer to our recent Medium post for more information about transaction fees. Alternatively, check out our gas comparison page (opens new window) for concrete numbers comparing the cost of transactions on Ethereum to transactions on Optimistic Ethereum.

Fees have to be paid in ETH. Click here for more information about how they are calculated.

# The Software

# Where can I find the source code for Optimism's implementation of the Optimistic Ethereum protocol?

All software used within Optimism's implementation of the Optimistic Ethereum protocol can be found under the Optimism organization on GitHub (opens new window). Most of this software is housed inside the Optimism Monorepo (opens new window). Refer to the monorepo README (opens new window) for more information about the structure of the repository and the role of each individual software component.

# What software license does Optimism use?

Optimism uses the permissive MIT License (opens new window) for a majority of its software. Code forked from go-ethereum (opens new window) under the name l2geth (opens new window) is licensed under the GNU GPLv3 (opens new window) in accordance with the original license (opens new window).

# Infrastructure

# What infrastructure providers support Optimistic Ethereum?

Provider Service Type Mainnet Support Kovan Testnet Support
Infura (opens new window) Node provider
Alchemy (opens new window) Node provider
QuickNode (opens new window) Node provider
Etherscan (opens new window) Block explorer
The Graph (opens new window) Data indexing
Dune Analytics (opens new window) Chain data analytics

# Where can I find RPC endpoints and connection details?

Connection details for all of our networks can be found on the Networks page (opens new window) of our documentation.

# Limitations and Disclaimers

Please read this section carefully.

Just like Ethereum, Optimistic Ethereum is an ever-improving system. We've chosen to enforce several temporary limitations in order to maintain a higher level of security and stability during these early days of the Optimistic Ethereum protocol. We highly recommend that you read this section carefully to better understand the current state of Optimistic Ethereum.

# The incentive contract for verification proofs is disabled

In the current release of the Optimistic Ethereum protocol, there may be rare cases in which the Sequencer submits a state root (transaction result) which is invalid and therefore could be challenged. As a result, we have not yet deployed the Bond Manager (opens new window) contract which compensates Verifier nodes for gas spent when submitting state root challenges. Verifier nodes in a default configuration do not run the TypeScript service which submits challenges (opens new window) in the event of mismatched state roots. Additionally, our upgrade keys have the ability to directly remove state roots without going through an uncompensated state root challenge.

# Optimism operates the only "Sequencer" node

A Sequencer node is a special node in an Optimistic Ethereum network that can order transactions on short timescales (on the order of minutes). This opens up the door to very fast transaction confirmation times with strong guarantees about finality. Eventually, the operator of the Sequencer node on a network will be determined by some governing mechanism. However, for now, Optimism PBC operates the only such node on every major OE network.

# Mainnet contract deployments are restricted by a whitelist

Contract deployments to the Optimistic Ethereum mainnet are currently restricted by a whitelist. We are slowly introducing new applications to the mainnet system in order to reduce the available exploit surface and to throttle usage. Please fill out our integration support signup form (opens new window) if you'd like to deploy an application to the OE mainnet. The Optimistic Kovan testnet (opens new window) is fully accessible to the general public.

# Optimism's codebase is only partially audited

Optimism follows a rolling audit process in which some parts of the codebase are audited while others are still being modified. An abridged record of past audits can be found below. A more complete record (including the exact scope of each audit) can be found on the public Optimistic Audit Record page (opens new window).

Please keep in mind that an audit is NOT a stamp of approval. Furthermore, many of the audited files have been modified since the listed audit took place.

Engagement Start Date Commit*
OpenZeppelin (opens new window) 2020-10-01 ethereum-optimism/[email protected] (opens new window)
Trail of Bits (opens new window) 2020-10-12 ethereum-optimism/[email protected] (opens new window)
DappHub (opens new window) 2020-11-18 ethereum-optimism/[email protected] (opens new window)
ConsenSys Dilligence (opens new window) 2020-03-08 ethereum-optimism/[email protected] (opens new window)
OpenZeppelin (opens new window) 2020-03-15 ethereum-optimism/[email protected] (opens new window)

*Commits here refer to the archived contracts (opens new window) repository which has since been incorporated into the optimism (opens new window) monorepo.

# Other Questions

Have a question that wasn't answered here? Please create an issue on GitHub (opens new window). We're aiming to keep this page up-to-date with the questions that are being most frequently at any given time. We appreciate everyone who has asked questions on GitHub and has helped make this page as useful as possible. ❤️