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Getting started with API3

API3➚ is a collaborative project to deliver traditional API services to smart contract platforms in a decentralized and trust-minimized way. It is governed by a decentralized autonomous organization (DAO), namely the API3 DAO.

The goal of API3 is to provide developers with an easy way to access off-chain resources from within their smart contracts, without having to worry about the security and trust implications of doing so.


API3 believes DeFi & Web3 can change the financial landscape with the right infrastructure and access to meaningful real world data. We aim to facilitate the true impact of smart contract applications by making a wide range of useful data easily accessible and scalable within smart contract functions.

Within this introduction of API3 we will explore;

  • APIs within the blockchain
  • Airnode & First-party oracles
  • Data feeds: Decentralized APIs (dAPIs)
  • API3 Market

If you wish to view a detailed discussion of the API3 project, read the API3 Whitepaper➚.

APIs in Web3

An API is used to communicate with a specific application to receive services or data from it. It is often a well-defined and documented protocol one can use to interact with an application programmatically. This has led to Web2 developers integrating APIs to build increasingly complex and capable applications.

In the context of decentralized applications, this definition is quite useless, and even misguiding. Instead, we should see APIs as channels businesses use to monetize their data and services. See the medium article APIs: The Digital Glue for additional background on APIs.

The API Connectivity Problem

Smart contracts operating on a blockchain are limited in their access to off-chain data, this phenomenon is referred to as the Oracle Problem. This is only worth consideration because it includes not being able to call the paid APIs described above.

All the game theoretic and cryptographic methods proposed for various oracle solutions essentially aim to provide smart contracts access to these paid APIs. Therefore, it would be more accurate to define the problem at hand as the API connectivity problem.

As you read about API3 offerings, you will discover that this redefinition will have ripple effects across the entire solution, from how the ecosystem is built to the lowest levels of the protocol.

Additionally, existing oracle solutions fall short because they fail to make this distinction, resulting in inferior solutions that depend on third-party oracles and ecosystems that exclude API providers. As such, API3 believes the oracle problem is ill-posed, instead we are faced with an API Connectivity Problem.


API3’s Airnode has been designed so API providers can easily run their own oracle nodes. It is an open source tool that allows them to provide their data on-chain, without an intermediary, to any decentralized app (dApp) interested in their services.

Through simplifying how an API provider can monetize their data within Web3, hundreds of Airnodes have been deployed. Once an API is connected to an Airnode, API data can be pushed on-chain.

Airnode also has range of common features built into it. These include implementations such as pre and post processing, authentication, or authorizations, to name a few.

Self operating

At its core, Airnode brings the ability for API providers to easily run their own first-party oracle nodes. Doing so means that it is the API provider's Airnode that places its signed API data on-chain.


Released under the MIT License.