Charon
Arbitrum

Who: Arbitrum built by Offchain Labs (startup spun out of research from Princeton University). Founders Ed Felten, Steven Goldfeder, Harry Kalodner, 9 employees on LinkedIn

What: Optimistic Rollup built to scale Ethereum. Transactions are sent to an aggregator, which plays the same role that a node plays in Ethereum. Client software can do remote procedure calls (RPCs) to an aggregator, using the standard API, to interact with the Arbitrum chain. The aggregator then makes calls to the EthBridge and produces transaction results to the client, just as an Ethereum node would. Aggregators post transaction batches to Ethereum, validators process batches and post assertions, everyone checks the assertion, fraud proof if it’s wrong, and to finish - assertion is confirmed.

Where: New York, New York

When: Founded 2018, currently in V4 testnet (mainnet release candidate)

Why: Original Academic paper published at USENIX Security 2018 to address privacy and scalability limitations of Ethereum

How: Transactions are sent to an aggregator, which plays the same role that a node plays in Ethereum. Client software can do remote procedure calls (RPCs) to an aggregator, using the standard API, to interact with the Arbitrum chain. The aggregator then makes calls to the EthBridge and produces transaction results to the client, just as an Ethereum node would. Aggregators post transaction batches to Ethereum, validators process batches and post assertions, everyone checks the assertion, fraud proof if it’s wrong, and to finish assertion is confirmed.

Strengths: uncertain

Weaknesses: Not live on mainnet yet

Traction: uncertain

Future Plans: Arbitum has Rollup in Beta, and has plans to launch channels and sidechains

Further Reading:

Arbitum research paper - https://offchainlabs.com/Arbitrum-USENIX.pdf

Why we chose Arbitrum: https://medium.com/mcdex/why-arbitrum-our-response-to-a-frequently-asked-question-c6243b2e43a6