Chainlink has a variety of active channels where you can find more information about the latest Chainlink announcements, discover helpful technical resources, and connect with other members of our rapidly growing community. Below is a list of official Chainlink channels. As a security best practice, always double-check the URL that you are visiting to ensure you are accessing official Chainlink properties. Chainlink will never ask for your passwords, seed phrases, private keys, or other confidential information. 

‍

• Blog: https://blog.chain.link/
• Discord: https://discordapp.com/invite/aSK4zew
• Docs: https://docs.chain.link/
• Events: https://chain.link/community/events
• GitHub: https://github.com/smartcontractkit/chainlink
• Newsletter: https://pages.chain.link/subscribe
• Reddit: https://www.reddit.com/r/Chainlink/
• Telegram: https://t.me/chainlinkofficial
• Twitter: https://twitter.com/chainlink
• WeChat: https://blog.chain.link/chainlink-chinese-communities/
• YouTube: https://www.youtube.com/c/chainlink

For inquiries related to security and support, please reach out to the admins of official Chainlink channels or email support@chain.link‍

Always practice a security mindset and ensure that users you are interacting with on community channels have verifiable trusted identities. You can confirm the accounts of official Chainlink community admin by clicking their names in the chat or viewing their handles under the official channel info.

Chainlink is the industry standard for building, accessing, and selling oracle services needed to power hybrid smart contracts on any blockchain. Through a decentralized oracle network, Chainlink allows blockchains to securely interact with external data and systems, providing the critical off-chain information and computations needed by complex smart contracts to become the dominant form of digital agreement.

A blockchain oracle is any system that services a smart contract by providing it with data from an off-chain source or connecting it with an off-chain system. Oracles enable connectivity between blockchains and real-world data by interfacing with external APIs and data feeds, allowing them to pull data for or push data from a smart contract.

Oracles allow smart contracts to interact with real-world data from off-chain sources. Without oracles, smart contracts can only access data generated on the blockchain, severely limiting their potential applications. Most of the valuable real-world use cases for smart contracts require off-chain data to trigger proper execution and often an integration with existing payment rails to settle a contract. For example, a smart contract may require market data from a trusted source like the NYSE to trigger a transaction. It may also require the ability to pay out escrowed fiat currency through legacy financial infrastructure, such as a bank checking account.

Real-world data, also known as off-chain data or external data, refers to the current global data infrastructure that exists outside of the blockchain that must be brought on-chain via oracles to be used by smart contract applications. Like a computer without the Internet, blockchain-based smart contracts have inherent value on their own, such as creating and swapping tokens. However, they become exponentially more powerful when externally connected to the vast and accelerating data and API economy taking root outside the blockchain ecosystem.

The oracle problem, also known as the “smart contract connectivity problem”, refers to a blockchain’s inability to natively pull data from or push data to any external off-chain system due to the strong security properties created by a blockchain’s consensus mechanism. 

Blockchain nodes are designed to perform standardized and uniform operations to generate consensus on a set of transactions (solving the double-spend problem). However, they are not suited to answer subjective questions about probabilistic real-world data, as blockchain nodes do not always have access to the same information, making generating consensus on even the most basic data requests challenging and source quality enforcement impossible. It is for this reason blockchains focus on generating definitive truth about the validity of transactions, but limit connections to any off-chain systems to ensure the network always remains live and produces deterministic results for incoming transactions. 

In order to create a bridge between the blockchain (on-chain) and the outside world (off-chain), there requires an additional and separate piece of infrastructure known as an “oracle”. However, the use of a centralized oracle can result in manipulated data inputs and outputs, meaning the oracle mechanism itself needs to be highly decentralized to ensure the security of a smart contract’s execution is maintained end-to-end.

The Chainlink Network refers to all of the decentralized oracle networks actively operating using the Chainlink protocol, including individual oracles, data providers running their own node, and node operators. By enabling smart contracts to quickly and securely connect to off-chain data sources using decentralized oracle networks, the Chainlink Network helps developers build more robust and diverse blockchain applications using real-world inputs and outputs. Additionally, as middleware between low-level blockchain protocols and external, off-chain data sources, the Chainlink Network serves as an abstraction layer for data providers to easily sell their existing APIs to any blockchain network.

A decentralized oracle network consists of multiple blockchain oracles run by independent node operators that are chosen to retrieve and validate data from several different off-chain sources. Each of the oracles’ responses within a decentralized oracle network are aggregated together to form a single trusted data point, which can be used to trigger smart contracts on any blockchain and really any system that needs highly reliable data that’s provably accurate. The data delivered on-chain can be hosted in a Reference Contract (pull model), and/or delivered directly to consuming smart contracts (push model). 

Chainlink’s Oracle Network is made up of multiple decentralized oracle networks running simultaneously and independently of one another. For example, if a smart contract requires data about the price of ETH, instead of relying on one individual blockchain oracle to pull price data from one API source, the smart contract can use a decentralized oracle network to have tens to hundreds of individual oracle nodes pull data from several API sources and then aggregate the result. See here for a live visualization of this data on-chain.

Through decentralized computation, Chainlink-powered decentralized oracle networks provide users superior security and reliability guarantees on the inputs and outputs of their smart contract, ensuring that both on-chain and off-chain components of a decentralized application are tamper-proof end-to-end.

Node operators are the entities that maintain and run the blockchain oracles that make up each Chainlink Oracle Network providing smart contracts on various blockchains access to external data and resources. These operators consist of professional validators for various blockchain networks, teams of highly experienced DevOps engineers, and organizations that focus specifically on building infrastructure for the Chainlink ecosystem. Additionally, external data vendors and API providers can monetize their data sets by running a Chainlink Node and providing signed data directly to smart contracts. Node Operators are able to configure their blockchain oracle node to connect to any off-chain data source and on-chain blockchain environment, providing a high degree of flexibility. 

Node operators within the Chainlink Network strictly adhere to the best security practices and use external monitoring systems to ensure a secure and reliable operation is maintained around the clock. Third-party marketplaces like market.link and reputation services like reputation.link provide users insight into the current and historical performance of each individual node operator. Additionally, anybody can become a Chainlink node operator, as no permission is required, and immediately begin providing smart contracts access to off-chain data. If you are interested in running a node, please navigate to our documentation here.

Chainlink provides users with a simple to integrate and pre-built decentralized oracle solution that can be utilized today by any smart contract on any blockchain. A Chainlink integration allows developers to focus on their application’s core business logic without needing to allocate precious resources to rebuilding infrastructure. Rolling your own oracle is extremely difficult and probabilistic as the oracle problem is complicated, technical, nuanced, and requires constant monitoring, upkeep, funding, and resources to maintain properly.

The ability to easily integrate a project with Chainlink’s decentralized oracle network has enabled numerous teams to avoid the hassle of building their own oracle, allowing them to instead focus on innovating and building use cases. Additionally, as Chainlink users collectively fund oracle networks as a public good, the costs of using Chainlink are far lower than attempting to build and manage your own solution. For example, a growing list of DeFi applications now use and collectively fund Chainlink price feeds. If you are interested in integrating with Chainlink, please reach out.

The Chainlink ecosystem includes hundreds of dApps, blockchains, node operators, and data providers, as well as an expansive research and open-source development community. The Chainlink Network powers the leading DeFi applications including Aave, Synthetix, and yEarn, securing billions of dollars in user funds. As Chainlink is a permissionless framework for building oracles, anybody can join the network at any time and immediately start contributing to the growing ecosystem. See the Chainlink price feeds page for a more in-depth list of users, sponsors, and node operators.

The Chainlink Network is composed of the highest-quality, Sybil-resistant oracle nodes that are operated by leading DevOps and security teams, such Deutsche Telekom’s T-Systems, who have decades of experience running mission-critical infrastructure. The security-reviewed and tamper-resistant nodes that comprise Chainlink oracle networks are highly transparent: their performance and reputation metadata is made publicly available to users and can be found on-chain or on third party sites such as reputation.link and market.link.

Chainlink also employs a defense in depth approach where multiple security solutions are used in combination to increase oracle network robustness and reliability. This includes privacy-preserving cryptography like DECO, trusted hardware such as Town Crier, cryptoeconomic security through implicit/explicit staking, and much more.

The Chainlink Network consists of hundreds of professionally-operated and community-run nodes, allowing for the creation of numerous Sybil-resistant and tamper-proof oracle networks that can scale up in decentralization as the value being secured rises. Chainlink nodes are operated by professional DevOps and security teams with decades of experience operating mission-critical infrastructure and are already securing billions of dollars of value across multiple blockchain networks. The performance and reputation data about each Chainlink node can be found on-chain or on third party sites such as reputation.link and market.link.

Chainlink is an open-source project and publishes code under the MIT License on GitHub.

High-quality data with premium APIs - The Chainlink Network has credential management capabilities, meaning it can fetch and deliver data to smart contracts from premium, password-protected data sources. While free data APIs are useful, most inputs that trigger transactions related to secure user funds will likely need to come from premium APIs. 

‍Flexibility - The Chainlink Network is a highly flexible and blockchain-agnostic oracle framework utilized by DeFi applications, web services, and traditional enterprises alike. By acting as a universal blockchain abstraction layer, users can leverage Chainlink to transmit any kind of data to and from any blockchain environment as desired. 

‍Highly secure and transparent nodes - Chainlink oracle networks consist of security-reviewed and tamper-resistant nodes, such as Deutsche Telekom’s T-Systems. These nodes are highly transparent, and their performance and reputation metadata are publicly available to all users (reputation.link). 

Decentralized and Sybil-resistant networks - Chainlink is the most decentralized oracle network, consisting of security-reviewed nodes that are backed by professional teams, allowing for the creation of numerous Sybil-resistant and tamper-proof oracle networks that can scale up as the value being secured rises. 

Defense in depth - Chainlink employs a defense in depth approach where multiple security solutions are used in combination to increase oracle network robustness and reliability. This includes privacy-preserving cryptography like DECO, trusted hardware such as Town Crier, cryptoeconomic security through implicit/explicit staking, reputation systems, and much more. This multi-layered approach to security increases Chainlink’s end-to-end reliability.

Adoption and network effects - Chainlink is the most widely used and adopted oracle solution in DeFi, securing billions in value in production for innovative DeFi protocols such as Aave, Synthetix, yearn.finance, and creating a growing network effect attracting more users. Chainlink has undergone numerous security audits and has been time-tested on mainnet. 

Solid security foundation and world-class research - Chainlink is supported by a multitude of leading engineers and academics, such as Chainlink Labs Chief Scientist Ari Juels. The researchers working on the Chainlink protocol are industry experts in blockchain oracles and are responsible for some of the most innovative developments in the space, such as DECO, VRF, Mixicles, Town Crier, and more. 

Chainlink nodes can access any authenticated or premium data source API through the use of modular external adapters. External adapters can be written in any programming language and hosted as a serverless function on any cloud provider or web server. These adapters allow Chainlink nodes to access a wide array of data sources, including authenticated and private APIs that require sensitive password keys, such as enterprise backends and subscription-based sources. Thus, Chainlink nodes have a high degree of flexibility as API credentials can be kept off-chain and stored securely, separate from the node itself.  

Chainlink oracle networks operate using multiple layers of data aggregation to ensure there is no single point of failure or any reliance on a single source of truth that could be corrupted. This redundancy is not only required to ensure high value smart contracts consume highly refined data, but also to ensure Chainlink Price Feeds provide full market coverage that reflects the true market price of assets. With Price Feeds securing billions in user funds, these layers of aggregation secure the DeFi ecosystem.

Chainlink uses multiple layers of aggregation to ensure broad market coverage and data quality. 

‍

The first aggregation layer is at the data source level where professional data aggregation firms (e.g. BraveNewCoin, CoinGecko) fetch market data from hundreds of exchanges, taking into account volume and liquidity differences, and generate a single weighted reference price point. The second aggregation layer is at the node operator level where each individual Chainlink oracle node sources price data from multiple data aggregation firms and takes the median, mitigating outliers, API downtime, and ensuring nodes do not rely on any one source. The third aggregation layer is at the oracle network level where the responses from multiple oracle nodes is aggregated by taking the median, ensuring no individual node has control over the resulting data point delivered to contracts. All of this together ensures smart contracts consume only the highest quality data that reflects the true market wide price.

For more information on secure oracle design, refer to our articles on the importance of data quality for DeFi smart contracts and the three levels of data aggregation in Chainlink Price Feeds. 

The original Chainlink White Paper outlines initial parameters for rating a node’s reputation: total number of assigned requests, total number of completed requests, total number of accepted requests, average time to respond, and amount of penalty payments. 

Secure Data Links’ Chainlink Oracle Reputation system collects and tracks these parameters to rate nodes: total transactions, job completion ratio, average gas price per transaction, sum of gas prices within a 10-minute window, average gas used per transaction, total gas used in a 10-minute window, average response time in blocks, total response time in a 10-minute window, average response time in seconds, and total response time in seconds within a 10-minute window. The system is consistently being enhanced with new services and features.

The Chainlink Price Feeds page provides real-time visualizations of each decentralized price feed that provides on-chain exchange rates for cryptocurrencies, stablecoins, commodities, and indices. Users can explore each individual Price Feed, which offer transparency around which nodes power each feed, each node’s latest response, how often feed updates occur, the gas price paid by each node, the users sponsoring each feed, and hyperlinks to on-chain transactions.

LinkPool’s Market.link is a permissionless marketplace that allows node operators to display their historical performance and list what oracle services they offer. Users can use this data to filter and analyze each node’s revenue, gas costs, and response times. Developers can also query the Chainlink Market’s Metrics API to access all of this raw data themselves and build their own analysis framework using real-time data regarding the performance of the Chainlink Network.

Secure Data Links’ Chainlink Oracle Reputation site Reputation.link allows users to inspect an individual node operator’s performance statistics, including average response time, job completion ratio, and total LINK earned. Users can also get a high-level overview of the various metrics regarding the Chainlink Network over the past seven days such as the total number of requests, price feeds, oracle nodes, payments, average response time, and more.

Through off-chain reporting and Threshold Signatures, Chainlink oracle networks can scale to thousands of secure nodes within a network. Instead of each node making their own on-chain transaction for each update, node responses are aggregated off-chain, and only a single transaction needs to be submitted on-chain. The security of data is cryptographically maintained throughout the entire process. This allows for the creation of Chainlink networks that are highly decentralized while remaining cost-efficient and secure against manipulation through a defense in depth approach. Additionally, unlike other oracle projects, each Chainlink oracle network is entirely independent of one another and does not affect the scalability or throughput of any other Chainlink network. 

Off-Chain Reporting (OCR) is the third and latest version of the Chainlink Core software client run by Chainlink nodes, which significantly improves the efficiency of how data is aggregated by Chainlink oracles. OCR reduces operating costs by up to 90% and enables the Chainlink Network to generate a 10x increase in the amount of secure, real-world data available to smart contract applications. 

OCR allows Chainlink nodes to communicate off-chain and aggregate data at zero gas costs using a distributed, peer-to-peer network. In OCR’s computation model, each node fetches data from one or multiple data sources, signs it with their unique private key, and broadcasts it to the rest of the oracle network off-chain. Once a sufficient number of responses have been generated, a single transaction is transmitted on-chain containing every node’s observation. The oracle report and node signatures are then validated on-chain by a smart contract, providing the transparency and end-to-end security guarantees that are fundamental to Chainlink oracle networks. 

All Chainlink nodes operating in-production run the OCR and FluxMonitor clients in parallel to achieve multi-client diversity and security through redundancy. For a deeper dive into OCR’s design goals and report generation process, read the OCR protocol paper.

Off-chain computation refers to trust-minimized executions that are performed outside of a blockchain environment by Decentralized Oracle Networks (DONs). The Chainlink Network provides a wide range of off-chain computations that significantly enhance the capabilities of smart contracts and blockchain networks, including scalable code execution, oracle update transaction batching, random number generation, privacy-preserving contracts, fair transaction ordering, and more. The off-chain computations performed by DONs extend Chainlink’s functionality far beyond secure data delivery while meeting the decentralized computation guarantees that are fundamental to blockchain technology.

Hybrid smart contracts are an evolution of smart contract design that was pioneered in the Chainlink 2.0 Whitepaper, in which contracts are securely composed of both on-chain and off-chain computing resources. Hybrid smart contracts are made possible by Chainlink Decentralized Oracle Networks (DONs), which provide a multiplicity of off-chain services to existing and future blockchain networks, enabling feature-rich, privacy-preserving, and scalable smart contract applications.

Chainlink Price Feeds are decentralized oracle networks that provide aggregated financial market data used by leading DeFi applications such as Aave, Synthetic, yearn.finance, and more. Powered by a multitude of professional, security-reviewed oracle nodes and premium data aggregators, these purpose-built price feeds provide broad market coverage on a wide array of assets and enable developers to rapidly create innovative smart contract applications that require a secure source of external market data. 

Chainlink Price Feeds are a community resource sponsored by a large collection of users and Chainlink, creating highly secure and decentralized oracle networks through the aggregation of user fees. With each additional user, existing and future users gain the benefits of a more cost-efficient and secure oracle network than they could afford on their own. As the DeFi ecosystem has grown, Chainlink Price Feeds have become a widely adopted solution that is lowering the barrier to creating highly secure financial smart contract applications.

Chainlink VRF brings secure random number generation to the blockchain. Chainlink VRF solves the difficult problem of providing an on-chain source of randomness that is publicly verifiable to be authentic and tamper-proof. Many smart contracts are augmenting the value they can create by utilizing Chainlink VRF, specifically applications such as gaming dApps that must prove to their users that their source of randomness is provably fair and resistant to manipulation from any external entity. Chainlink VRF enables and accelerates the development of smart contracts focused on blockchain gaming, security, layer-two protocols, and various other use cases.

Chainlink Proof of Reserve provides smart contracts with the data required to calculate the true collateralization of any on-chain asset backed by off-chain reserves such as stablecoins and cross-chain assets. Operated by a decentralized network of oracles, Chainlink Proof of Reserve enables the autonomous auditing of collateral used within DeFi in real-time, ensuring users’ funds are protected from unforeseen fractional reserve practices and other fraudulent activity from off-chain custodians. This provides both the growing DeFi ecosystem and the traditional financial system a way to increase transparency of operations with definitive on-chain proof of any asset’s true collateralization.

Chainlink Keepers is a decentralized transaction automation solution that enables smart contracts to automate key functions and DevOps tasks in a highly reliable, trust-minimized, and cost-efficient manner. Individual developers, teams, and DAOs can utilize Chainlink Keepers as an off-chain computation layer to reliably automate key functions and unlock advanced utility.

DECO is a novel privacy-preserving oracle protocol that allows users to prove facts about their web (TLS) sessions to oracles without unveiling any confidential information on-chain. Developed by researchers at Cornell University and acquired by Chainlink, this technology extends the data security capabilities of HTTPS and TLS, guaranteeing that data remains private and tamper-proof during its delivery from various private and premium data sources. It does so by employing advanced cryptography and zero-knowledge proofs from any server using HTTPS/TLS, without revealing that data to the outside world or even to the final computation using the data. DECO creates a new method of providing private and premium data across the internet while maintaining its confidentiality and security at previously unachievable levels.

This additional level of data security enables previously inaccessible data to be made accessible to both existing web systems and various blockchains and smart contracts through Chainlink oracles. Using DECO-enabled Chainlink nodes:

• Premium data sources that have so far been unable to place high-quality data on public blockchains due to confidentiality concerns will be able to provide data to various blockchains and DeFi protocols. 
• Enterprises will be able to prove the state of private data to other enterprises and blockchain records without revealing internal data on-chain.
• Consumers will be able to prove personal data like identity or bank balances to smart contracts without giving applications full access to their personal accounts, maintaining their privacy.

Any individual or group that needs real-world data to power and secure the execution of their smart contracts can benefit from Chainlink’s robust and customizable framework for creating decentralized oracle networks. Today, hundreds of teams working on dApps, blockchains, industry consortiums, enterprise projects, and more rely on Chainlink to provide tamper-proof inputs and outputs for their smart contracts. Chainlink has become the de facto oracle solution for the DeFi space, supporting top projects like Aave, Synthetix, and yearn.finance, and securing billions in value across the sector.

If you’d like more information on how Chainlink could provide solutions for your project, join us in the Official Discord Channel and reach out through the integrations submission form.

Secure oracles that provide tamper-proof inputs and outputs for smart contracts are required for the vast majority of valuable smart contract use cases. Robust and decentralized Price Feeds for powering DeFi, verifiable randomness for on-chain gaming, additional security and transparency with Proof of Reserve, scalable and low-cost computation of Solidity smart contracts, premium weather data for parametric insurance, and a broad variety of real-world data for enterprise frameworks like the Baseline Protocol are just a small handful of applications powered by Chainlink’s network of decentralized oracles.

Additionally, Chainlink oracle networks not only benefit on-chain smart contracts but also benefit off-chain systems, providing them with a reliable source of censorship-resistant and tamper-proof data that is crypto-economically secured. High-value enterprise backend systems can use Chainlink’s data as inputs to ensure only the highest quality data is being utilized to trigger mission-critical business functions. This greatly broadens the use case of oracles and can provide the global economy with even more verifiable data sources around the definitive state of the world. 

Explore the blog post 77 Smart Contract Use Cases Enabled by Chainlink and the categories below for a deeper dive into applications of decentralized oracles:  

• Decentralized finance
• External payments
• Gaming and randomness
• Insurance
• Enterprise systems
• Supply chain
• Utilities
• Authorization and identity
• Government

Decentralized finance (often referred to as DeFi) is a growing movement around recreating common financial instruments from traditional finance using decentralized infrastructure. Rather than needing centralized entities to facilitate the movement of financial markets, users can access, trade, and lend assets using open-source software running on decentralized networks. The result is self-running, peer-to-peer financial markets based on transparency, open access, and data-driven automation.

Chainlink oracle networks enable tamper-resistant and sustainable price feeds that are currently in use by several top DeFi applications to secure billions of dollars worth of locked value. By enabling smart contracts to access new forms of data as inputs, while retaining the underlying security and reliability guarantees of the smart contract, Chainlink plays a crucial role in the DeFi industry’s growth.

In the current price reference feed model, independent nodes in the Chainlink Network monitor for price changes off-chain, trigger an update when the price change hits a defined threshold (e.g. 1%), fetch aggregated market prices from high-quality data providers, and then aggregate node responses to generate a highly available and manipulation-resistant price update on-chain. Smart contracts can then access an extremely accurate price using a simple function call.

Some examples of price feed users include:

• Synthetic asset platforms that require the price of real-world assets in order to mint their representation on-chain. These platforms use Chainlink reference contracts to create tokens tied to real-world assets, such as gold, indices, or even car loans.
• Lending and borrowing platforms that require a price feed to ensure the total value of the collateral. These platforms use Chainlink to issue and settle loans, liquidate collateral, and calculate interest payments.
• Stablecoins that require a price feed to assert the value of the underlying collateral backing the asset. These platforms use Chainlink to create stablecoins pegged to fiat currency, currency baskets, or commodities.
• Asset management platforms that require a reliable price feed for the critical rebalancing of asset ratios. These platforms use Chainlink to power a decentralized exchange (DEX), adjust capital pools, or facilitate multiple forms of payment.

You can find a full list of live Chainlink Price Feeds here.

Stay up-to-date with all official Chainlink announcements by following the Chainlink Twitter and subscribing to the Chainlink newsletter. The Chainlink blog provides in-depth articles for those looking for more information about announcements and Chainlink technology. For events and meetups in your local area, visit the Chainlink Events page. If you are a developer, please join our highly active community on Discord.

The Chainlink development team is continuously building the network and protocol. To keep up to date with current progress you can follow the Chainlink Github and Pivotal Tracker. You can find a full list of open roles on the Chainlink Labs careers page.

There are numerous projects working on the development of the Chainlink ecosystem, including Chainlink Labs. You can find a full list of open roles on the Chainlink Labs careers page.