Chainlink (blockchain)

Chainlink is a decentralized blockchain oracle network like Tellor built on 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. Its creators claim it can be used to verify whether the parameters of a smart contract are met in a manner independent from any of the contract's stakeholders by "connecting the contract directly to real-world data, events, payments, and other inputs".[5][self-published source?]

Chainlink Logo Blue.svg
Original author(s)Sergey Nazarov, Steve Ellis, Dr. Ari Juels [1][2]
Written inSolidity, GoLang
Operating systemBlockchain-agnostic
Source modelOpen source
LicenseMIT License
Circulating supply453,509,553[citation needed]
Supply limit1,000,000,000
Market capUS$10.96 billion (2021-09-23)[citation needed]

Chainlink TokenEdit

Chainlink's LINK token is an ERC677 token, an extension of ERC20. Tokens act as data payloads, feeding the required data from off-chain sources to smart contracts, which then act accordingly in response to the data provided by the token.[6][better source needed] According to 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 ERC20 wallet, as the ERC677 token retains all the functionality of an ERC20 token.[7][self-published source?]


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

Chainlink was created in 2017 by Sergey Nazarov and Steve Ellis,[8] who co-authored a white paper introducing the Chainlink protocol and network with Cornell University professor Ari Juels the same year.[9] Chainlink acts as a "bridge" between a blockchain and off-chain environments.[10] The network is used by smart contracts and was formally launched in 2019.[8]

In 2018, Chainlink integrated Town Crier, a trusted execution environment-based blockchain oracle that Juels also worked on. Town Crier connects the Ethereum blockchain with web sources that use HTTPS.[11] In 2020, Chainlink integrated DECO, a Cornell project co-created by Juels. DECO is described by its authors as a protocol that uses zero-knowledge proofs to allow users to prove information is true to a blockchain oracle without revealing sensitive information, such as birth dates.[12]

Chainlink published a second white paper in April 2021. That paper, Chainlink 2.0: Next Steps in the Evolution of Decentralized Oracle Networks, detailed a vision for expanding the role and capabilities of decentralized oracle networks to include hybrid smart contracts, which utilize on-chain code and off-chain services provided by oracle networks.[13] More than 650 entities have integrated with Chainlink as of July 2021,[14] including the Associated Press,[15] Google, and Deutsche Telekom.[16]


  1. ^ Ellis, Steven; Juels, Ari; Nazarov, Sergey (4 September 2017). "ChainLink A Decentralized Oracle Network" (paper). Retrieved 5 July 2021 – via Microsoft Bing.
  2. ^ Caldarelli, Giulio (November 2020). "Understanding the Blockchain Oracle Problem: A Call for Action". Information. (University of Verona, 37129 Verona, Italy). 11 (11): 509. doi:10.3390/info11110509.CS1 maint: location (link)
  3. ^ Breidenbach, Lorenz; Chacin, Christian; Chan, Benedict; Coventry, Alex; Ellis, Steven; Juels, Ari; Koushanfar, Farinaz; 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" (paper). University of Bern, Cornell Tech, University of California, University of Illinois Urbana-Champaign, Duke University. pp. 2, 78. Retrieved 4 July 2021 – via Microsoft Bing
  4. ^ Anadiotis, George. "Chainlink launches Mainnet to get data in and out of Ethereum smart contracts". ZDNet. Retrieved 2021-08-29.
  5. ^ "Decentralized Oracles for Blockchain Use Cases | Chainlink". Retrieved 2021-07-24.
  6. ^ "ERC: transferAndCall Token Standard · Issue #677 · ethereum/EIPs". GitHub. Retrieved 2021-07-24.
  7. ^ "FAQ | Chainlink Documentation". Retrieved 2021-07-24.
  8. ^ a b Anadiotis, George (May 30, 2019). "Chainlink launches Mainnet to get data in and out of Ethereum smart contracts". ZDNet. Retrieved August 3, 2021.
  9. ^ Ellis, Steve; Juels, Ari; Nazarov, Sergey (September 4, 2017). "Chainlink: A Decentralized Oracle Network" (PDF). Chainlink. Retrieved August 3, 2021.
  10. ^ 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 (34). p. 30.
  11. ^ Orcutt, Mike (November 19, 2018). "Blockchain smart contracts are finally good for something in the real world". MIT Technology Review. Retrieved August 3, 2021.
  12. ^ Brett, Charles (September 4, 2020). "Chainlink acquires DECO from Cornell". Enterprise Times. Retrieved August 3, 2021.
  13. ^ Anadiotis, George (April 15, 2021). "Chainlink 2.0 brings off-chain compute to blockchain oracles, promotes adoption of hybrid smart contracts". ZDNet. Retrieved July 27, 2021.
  14. ^ Hatze, Vlad (July 25, 2021). "Chainlink Onboarding Partners at the Speed of Light — DailyCoin". DailyCoin. Retrieved August 3, 2021.
  15. ^ Castillo, Michael del (November 3, 2020). "How To Track Official Election Results On Ethereum And EOS". Forbes. Retrieved July 26, 2021.
  16. ^ Brown, Eileen (November 10, 2020). "Chainlink VRF makes blockchain games more trustworthy by using verifiable on-chain source of randomness". ZDNet. Retrieved August 3, 2021.