# Chainlink (blockchain oracle)

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Cryptocurrency and Ethereum token

Chainlink Denominations Plural Chainlink Code LINK Development Original authors Sergey Nazarov Steve Ellis Ari Juels[1][2] White paper chain.link/whitepaper Code repository github.com/smartcontractkit/chainlink Written in Solidity, Go Operating system Blockchain-agnostic Source model Open source License MIT License Ledger Supply limit 1,000,000,000 Website Website chainlinklabs.com

**Chainlink** is a decentralized [blockchain oracle](/source/Blockchain_oracle) network. Chainlink's token is on [Ethereum](/source/Ethereum).[3][4] The network is intended to be used to facilitate the transfer of tamper-proof data from off-chain sources to on-chain [smart contracts](/source/Smart_contract).[5]

## History

Chainlink was created in 2017 by [Sergey Nazarov](/source/Sergey_Nazarov_(businessman)) and Steve Ellis,[4] who co-authored a [white paper](/source/White_paper) introducing the Chainlink [protocol](/source/Protocol_(network)) and network with [Cornell University](/source/Cornell_University) professor [Ari Juels](/source/Ari_Juels) the same year.[1] Chainlink acts as a "bridge" between a [blockchain](/source/Blockchain) and off-chain environments.[6] The network, which services [smart contracts](/source/Smart_contracts), was formally launched in 2019.[4]

In 2018, Chainlink integrated Town Crier, a [trusted execution environment](/source/Trusted_execution_environment)-based blockchain oracle that Juels also worked on. Town Crier connects the [Ethereum](/source/Ethereum) blockchain with web sources that use [HTTPS](/source/HTTPS).[7]

In 2020, Chainlink integrated DECO, a Cornell project co-created by Juels. DECO is described by its authors as a [protocol](/source/Cryptographic_protocol) that uses [zero-knowledge proofs](/source/Zero-knowledge_proofs) to allow users to prove information is true to a blockchain oracle without revealing [sensitive information](/source/Sensitive_information), such as birth dates.[8]

In 2020, Chainlink launched a proof-of-reserve (PoR) system intended to help cryptocurrency projects and tokenized-asset issuers verify asset backing.[9]

In 2022, Chainlink announced and launched BUILD, a program under Chainlink Economics 2.0 for projects that commit a portion of their fees and incentives to support the Chainlink ecosystem.[10]

In 2023, Chainlink introduced the Cross-Chain Interoperability Protocol (CCIP), designed to enable communication between applications across blockchains and traditional financial systems.[11] In August 2023, SWIFT reported results from experiments using CCIP with SWIFT messaging to transfer tokenized assets across multiple public and private blockchains.[12] In November 2024, a SWIFT, UBS Asset Management, Chainlink working under the [Monetary Authority of Singapore](/source/Monetary_Authority_of_Singapore) demonstrated settlement of tokenized fund subscriptions and redemptions over the SWIFT network using Chainlink.[13]

In 2025, the [United States Department of Commerce](/source/United_States_Department_of_Commerce) used Chainlink to publish U.S. government macroeconomic data on blockchains.[14] In the same year, Chainlink, J.P. Morgan's Kinexys, and Ondo Finance executed a cross-chain Delivery vs. Payment (DvP) transaction using the Chainlink Runtime Environment.[15] On October 31, 2025, the [Hong Kong Monetary Authority](/source/Hong_Kong_Monetary_Authority) and the [Central Bank of Brazil](/source/Central_Bank_of_Brazil) carried out a cross-border trade finance pilot using CBDCs and smart contracts. The test connected Brazil's Drex wholesale CBDC system with HKMA's Ensemble platform through Chainlink.[16]

## Technology

A visual representation of Chainlink's "smart bond architecture"

Chainlink's oracle network allows blockchains to connect to off-chain data and computation resources.[17][18]

## LINK token

LINK is a utility and governance token of Chainlink. The trade value derived from these tokens is used to pay node operators for retrieving data from smart contracts, and also for deposits placed by node operators as required by contract creators. Tokens can be stored in any ERC-20 wallet, as the ERC677 token retains all the functionality of an ERC-20 token.[19] Community participants can stake LINK to support the network's cryptoeconomic security.[20]

## References

1. ^ [***a***](#cite_ref-Whitepaper1_1-0) [***b***](#cite_ref-Whitepaper1_1-1) Ellis, Steven; Juels, Ari; Nazarov, Sergey (4 September 2017). ["ChainLink A Decentralized Oracle Network"](https://web.archive.org/web/20171006080308/https://link.smartcontract.com/whitepaper). *chain.link*. Archived from [the original](https://link.smartcontract.com/whitepaper) (paper) on 6 October 2017. Retrieved 8 October 2022.

1. **[^](#cite_ref-Caldarelli_2-0)** Caldarelli, Giulio (November 2020). ["Understanding the Blockchain Oracle Problem: A Call for Action"](https://doi.org/10.3390%2Finfo11110509). *[Information](/source/Information_(journal))*. **11** (11). Verona, Italy: [MDPI](/source/MDPI): 509. [doi](/source/Doi_(identifier)):[10.3390/info11110509](https://doi.org/10.3390%2Finfo11110509).

1. **[^](#cite_ref-whitepaper2_3-0)** Breidenbach, Lorenz; Chacin, Christian; Chan, Benedict; Coventry, Alex; Ellis, Steven; Juels, Ari; [Koushanfar, Farinaz](/source/Farinaz_Koushanfar); Miller, Andrew; Magauran, Brendan; Moroz, Daniel; Nazarov, Sergey; Topliceanu, Alexandru; Tramèr, Florian; Zhang, Fan (15 April 2021) [2017]. ["Chainlink 2.0. The Next Steps in the Evolution of Decentralized Oracle Networks 9 Economics and Cryptoeconomics Staking"](https://research.chain.link/whitepaper-v2.pdf) (paper). *chain.link*. [University of Bern](/source/University_of_Bern), [Cornell Tech](/source/Cornell_Tech), [University of California](/source/University_of_California), [University of Illinois Urbana-Champaign](/source/University_of_Illinois_Urbana-Champaign), [Duke University](/source/Duke_University). research.chain.link. pp. 2, 78. [Archived](https://web.archive.org/web/20210415141430/https://research.chain.link/whitepaper-v2.pdf) (PDF) from the original on 2021-04-15. Retrieved 4 July 2021.

1. ^ [***a***](#cite_ref-Anadiotis-2019_4-0) [***b***](#cite_ref-Anadiotis-2019_4-1) [***c***](#cite_ref-Anadiotis-2019_4-2) Anadiotis, George (May 30, 2019). ["Chainlink launches Mainnet to get data in and out of Ethereum smart contracts"](https://www.zdnet.com/finance/blockchain/chainlink-launches-mainnet-to-get-data-in-and-out-of-ethereum-smart-contracts/). *[ZDNet](/source/ZDNet)*. Retrieved August 3, 2021.

1. **[^](#cite_ref-Handbook_5-0)** Nikbakht, Ehsan; Baker, H Kent; Smith, Sean Stein (9 March 2021). [*The Emerald Handbook of Blockchain for Business*](https://books.google.com/books?id=jKYgEAAAQBAJ&dq=chainlink+blockchain&pg=PA182). Emerald Publishing Limited. [ISBN](/source/ISBN_(identifier)) [9781839821981](https://en.wikipedia.org/wiki/Special:BookSources/9781839821981). Retrieved 8 March 2022.

1. **[^](#cite_ref-Ranica1_6-0)** Arrowsmith, Ranica (December 1, 2020). "Tech, accelerated; 2020 was a hothouse for technology, speeding up the already rapid pace of development and adoption". *[Accounting Today](/source/Accounting_Today)*. No. 34. p. 30.

1. **[^](#cite_ref-MIT1_7-0)** Orcutt, Mike (November 19, 2018). ["Blockchain smart contracts are finally good for something in the real world"](https://www.technologyreview.com/2018/11/19/139032/blockchain-smart-contracts-can-finally-have-a-real-world-impact/). *[MIT Technology Review](/source/MIT_Technology_Review)*. Retrieved August 3, 2021.

1. **[^](#cite_ref-Enterprise1_8-0)** Brett, Charles (September 4, 2020). ["Chainlink acquires DECO from Cornell"](https://www.enterprisetimes.co.uk/2020/09/04/chainlink-acquires-deco-from-cornell/). *Enterprise Times*. Retrieved August 3, 2021.

1. **[^](#cite_ref-9)** Cai, Gangshu (2024). [*Supply Chain Finance: Mechanisms, Risk Analytics, and Technology*](https://www.google.com/books/edition/Supply_Chain_Finance/lM4gEQAAQBAJ?hl=en&gbpv=1&dq=%22Proof+of+Reserve%22+AND+%22Chainlink%22&pg=PA479&printsec=frontcover). Switzerland: Springer Nature. p. 479. [ISBN](/source/ISBN_(identifier)) [9783031561252](https://en.wikipedia.org/wiki/Special:BookSources/9783031561252).

1. **[^](#cite_ref-10)** ["Chainlink BUILD Program"](https://chain.link/build-program). *Chain.link*. Chainlink. Retrieved 13 January 2026.

1. **[^](#cite_ref-11)** Ba, Shusong; Wang, Yang; Bai, Haifeng; Zhu, Haokang Thomas (2025). [*RWA Tokenisation in Web 3.0 Era*](https://books.google.com/books?id=Oyh2EQAAQBAJ&pg=PA100&dq=%22Cross-Chain+Interoperability+Protocol%22+AND+%22Chainlink%22&hl=en&newbks=1&newbks_redir=1&sa=X&ved=2ahUKEwj295Tfsb6SAxXjRv4FHf6bMrAQ6AF6BAgJEAM). Singapore: Springer Nature. p. 100. [ISBN](/source/ISBN_(identifier)) [9789819676637](https://en.wikipedia.org/wiki/Special:BookSources/9789819676637).

1. **[^](#cite_ref-12)** ["Connecting blockchains: Overcoming fragmentation in tokenised assets"](https://www.swift.com/sites/default/files/files/results_report_swift_interoperability_experiments_final_310823.pdf) (PDF). *www.swift.com*.

1. **[^](#cite_ref-13)** ["Swift, UBS Asset Management, and Chainlink successfully complete innovative pilot to bridge tokenized assets with existing payment systems"](https://www.swift.com/news-events/press-releases/swift-ubs-asset-management-and-chainlink-successfully-complete-innovative-pilot-bridge-tokenized-assets-existing-payment-systems). *www.swift.com*.

1. **[^](#cite_ref-14)** Hall, Ian (August 30, 2025). ["US Department of Commerce starts posting GDP data on public blockchains"](https://www.globalgovernmentfinance.com/department-of-commerce-usa-gdp-data-public-blockchains/).

1. **[^](#cite_ref-15)** ["The LINK Between Worlds"](https://research.grayscale.com/reports/the-link-between-worlds). 19 November 2025.

1. **[^](#cite_ref-16)** Popowicz, Joasia E. (5 November 2025). ["HKMA-BCB trade finance link could be gamechanger, says expert"](https://www.centralbanking.com/fintech/7974010/hkma-bcb-trade-finance-link-could-be-gamechanger-says-expert).

1. **[^](#cite_ref-17)** Zhao, Yinjie; Kang, Xin; Li, Tieyan; Chu, Cheng-kang; Wang, Haiguang. ["Towards Trustworthy DeFi Oracles: Past, Present and Future"](https://arxiv.org/pdf/2201.02358.pdf) (PDF). *arxiv.org*.

1. **[^](#cite_ref-18)** Gansäuer, Robin; Ben Aoun, Hichem; Droll, Jan; Hartenstein, Hannes. ["Price Oracle Accuracy Across Blockchains: A Measurement and Analysis"](https://caaw.io/2025/papers/CAAW25_paper_22.pdf) (PDF). *caaw.io*.

1. **[^](#cite_ref-19)** ["FAQ | Chainlink Documentation"](https://docs.chain.link/docs/faq/#:~:text=The%20LINK%20token%20is%20an,as%20required%20by%20contract%20creators.). *docs.chain.link*. Retrieved 2021-07-24.

1. **[^](#cite_ref-20)** [*Financial Cryptography and Data Security. FC 2021 International Workshops*](https://books.google.com/books?id=nI5DEAAAQBAJ&dq=chainlink+token+ERC677&pg=PA116). Springer Berlin Heidelberg. 16 September 2021. [ISBN](/source/ISBN_(identifier)) [9783662639580](https://en.wikipedia.org/wiki/Special:BookSources/9783662639580).

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Adapted from the Wikipedia article [Chainlink (blockchain oracle)](https://en.wikipedia.org/wiki/Chainlink_(blockchain_oracle)) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Chainlink_(blockchain_oracle)?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.