Official repository for core projects comprising the Celo platform

This repository contains the source code for the Celo core projects including the smart contracts, wallet app, and other packages.

The source code for the Celo Blockchain which operates a node on the Celo Network is kept in a separate repo here.

Celo is oriented around providing the simplest possible experience for end users, who may have no familiarity with cryptocurrencies, and may be using low cost devices with limited connectivity. To achieve this, the project takes a full-stack approach, where each layer of the stack is designed with the end user in mind whilst considering other stakeholders (e.g. operators of nodes in the network) involved in enabling the end user experience.

The Celo stack is structured into the following logical layers:

The Celo Blockchain and Celo Core Contracts together comprise the Celo Protocol.

• Celo Blockchain: An open cryptographic protocol that allows applications to make transactions with and run smart contracts in a secure and decentralized fashion. The Celo Blockchain has shared ancestry with Ethereum, and maintains full EVM compatibility for smart contracts. However it uses a Byzantine Fault Tolerant (BFT) consensus mechanism rather than Proof of Work, and has different block format, transaction format, client synchronization protocols, and gas payment and pricing mechanisms. The network’s native asset is Celo Gold, exposed via an ERC-20 interface.
• Celo Core Contracts: A set of smart contracts running on the Celo Blockchain that comprise much of the logic of the platform features including ERC-20 stable currencies, identity attestations, Proof of Stake and governance. These smart contracts are upgradeable and managed by the decentralized governance process.

Topology of a Celo Network

• Applications: Applications for end users built on the Celo platform. The Celo Wallet app, the first of an ecosystem of applications, allows end users to manage accounts and make payments securely and simply by taking advantage of the innovations in the Celo protocol. Applications take the form of external mobile or backend software: they interact with the Celo Blockchain to issue transactions and invoke code that forms the Celo Core Contracts’ API. Third parties can also deploy custom smart contracts that their own applications can invoke, which in turn can leverage Celo Core Contracts. Applications may use centralized cloud services to provide some of their functionality: in the case of the Celo Wallet, push notifications and a transaction activity feed.

See Developer's Guide for full details about the design of the Celo protocol and other information about running these projects.

See the issue backlog for a list of active or proposed tasks. Feel free to create new issues to report bugs and/or request features. Please add labels to your issues, tagging the appropriate package/area.

All packages are licensed under the terms of the Apache 2.0 License unless otherwise specified in the LICENSE file at package's root.

Improvements and contributions are highly encouraged! See the contributing guide for details on how to participate.