Explore ContractKit and DAppKit, the first developer libraries for the Celo platform

C Labs
C Labs
Aug 19 · 4 min read
Example Savings Circle DApp built using the Celo SDK

In July, Celo open sourced the Celo Protocol, Core Contracts, and Wallet app. Today, we are excited to release the Celo SDK. The SDK is presently comprised of DAppKit and ContractKit, the first set of libraries to help developers build on top of Celo. With DAppKit, you can build an entirely new financial DApp that connects to the open source Celo Wallet and leverages the Celo Platform (EVM compatible). ContractKit makes it easy to interact with Celo smart contracts and assets, making it simple to add Celo to your own existing application.

For developers, especially those aligned with the Celo mission to reach the one in three adults without a bank account, the Celo SDK makes that reach possible.

Why does this matter?

Celo’s mission is to build a monetary system that create the conditions of prosperity for all. We imagine a world with beautiful money that works for everyone. The only way to achieve this vision is to empower communities around the world to design and build solutions that work for them. The first step is creating developer tools to do just that; an easy solution to leverage the Celo platform from anywhere in the world.

Unlocking User Adoption

The Celo SDK provides the unique solution of stable, decentralized infrastructure paired with features to build for today’s mobile-first generation. Today, many of the popular blockchain-based applications (“DApps”) don’t work on mobile phones. Yet half of the world’s internet traffic is on mobile (source). And the number of unique mobile subscribers is projected to grow, reaching 5.9 billion by 2025, equivalent to 71% of the world’s population (source). Accessible, mobile applications will be the key to user adoption.

Around the world, through over 150 in depth user research interviews, we’ve seen how phone storage and data are scarce resources. When we think about reaching the first billion users of decentralized systems, we imagine an ecosystem and experience that feels organic and doesn’t require a device, a mobile app, and a DApp browser for access.


The Celo SDK is comprised of two new developer tools: DAppKit and ContractKit.

DAppKit allows any DApp developer to easily build Expo Applications that contribute to a resource-efficient mobile ecosystem and simple experience for the user. If a user already has the Celo Wallet, DAppKit allows a DApp to, when granted permission by the user, use the Celo Wallet’s trusted ultralight client to sign transactions.

For developers who already have a mobile app, ContractKit allows anyone to easily augment their own applications to leverage features of Celo Smart Contracts, such as adding Celo Dollars or Celo Gold with a simple Typescript interface.

Would you like to see your favorite technology supported by the Celo SDK? Comment below and visit the GitHub page and contribute to development!

Possibilities on Celo

C Labs, the team working on Celo, built the first use case on the Celo protocol, an open source peer-to-peer social payments app. Through our user research, we’ve validated many other use cases for Celo including: peer-to-peer lending (savings circles), micro loans, and micro insurance. Celo has been designed from the ground up with the primitives and attributes to support a rich financial ecosystem.

As a proof of concept, we’re releasing an example savings circle application on GitHub that we hope will inspire builders to join us in creating an open, inclusive financial system.

Example Savings Circle DApp built using the Celo SDK

What do you want to create? Comment below!

Global Ecosystem Fund

To support entrepreneurs around the world, Polychain has announced the Celo Ecosystem Fund, with founding investors Andreessen Horowitz and Celo. Investments are strategic, seed-stage deployments into tools and services which will leverage Celo’s protocol to build new financial infrastructure, particularly in the developing world. Apply at celo.org/connect#fund.


Stay connected

A Note on Terminology

An explanation of some of the terminology in an attempt to make crypto more approachable.

  • Celo Celo is an open platform that makes financial tools accessible to anyone with a mobile phone.
  • C Labs — the team working on Celo, currently leading the development of the Celo protocol and Celo Wallet application (and authors of this announcement).
  • DApp — Short for “Decentralized Application”. Similar to an existing phone application but has backend code running on a decentralized peer-to-peer network (like Bitcoin or Celo).
  • DeFi — Decentralized Finance; open source software and networks without intermediaries in the financial space.
  • EVM — “Ethereum virtual machine” is a blockchain-based software platform. It allows developers to create decentralized applications on Ethereum (source).
  • SDK — “Software Development Kit” is a group of developer tools that enable the programming of mobile applications.
  • Smart Contracts — Self-executing contracts with the terms of the agreement between buyer and seller being directly written into lines of code (source).

The Celo Blog

Celo is an open platform that makes financial tools accessible to anyone with a mobile phone. Visit celo.org for info on the community, team, and technology.

C Labs

Written by

C Labs

C Labs is the team working on Celo. Celo is an open platform that makes financial tools accessible to anyone with a mobile phone.

The Celo Blog

Celo is an open platform that makes financial tools accessible to anyone with a mobile phone. Visit celo.org for info on the community, team, and technology.

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