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Q&A with Tezos developers Keefer Taylor and Luke Youngblood


What is Harbinger?

Harbinger is a decentralized price oracle for Tezos that is both cryptographically secure and self-sustaining. Harbinger enables data providers to cryptographically sign price data, which can then be posted by anyone on the Tezos network to an oracle contract. Regardless of who posts the data, you can verify that the data has not been modified because the oracle contract will only accept price updates where the signature was generated by the data provider. It is self-sustaining because the fees to perform regular price updates can be paid by the staking rewards received on the Tezos network. A single roll of 8,000 tez, delegated to a baker on the Tezos network, will earn enough staking rewards to pay for price updates every 15 minutes, perpetually. Today, Harbinger supports price data from Coinbase Pro, Binance, OKEx, and Gemini cryptocurrency exchanges.

What are some of the potential applications of Harbinger? What can a price oracle enable on Tezos?

Trusted and accurate price oracles like Harbinger can be used to secure collateralized debt positions on lending platforms. They can also be used to price options and futures contracts, as well as provide insurance and downside risk protection. Any financial decision that requires accurate price data can benefit from using Harbinger. For example, a lending platform where you can borrow USDtz against your tez holdings will need to know what the price of tez is, so that it can make sure you have enough collateral to fully back your loan.

What is Kolibri?

Kolibri is an upcoming decentralized finance (Defi) application that will enable any tez holder on the Tezos network to mint a stablecoin, kUSD, that is backed by the tez they hold. kUSD is a new stablecoin that is pegged 1:1 to the US dollar, is backed by tez and secured by the Harbinger price oracle. Kolibri uses Harbinger to ensure that the value of the tez backing kUSD always remains greater than the kUSD that has been minted. As a tez holder, when you mint kUSD, you can continue to delegate to the baker of your choice and receive staking rewards on the tez you hold, even while it is used to secure your kUSD. Every cycle, when you earn more te, you’ll have more collateral, which will allow you to mint more kUSD.

Did you always have a project like Kolibri in mind when you created Harbinger?

Yes. We knew that in order to create an algorithmic stablecoin like kUSD, we would need a trusted and accurate source of price data for the collateral that would secure it. Because it didn’t yet exist on Tezos, we decided to create it.

What’s next? Where do Kolibri and Harbinger go from here? Anything else that you would like to share?

We are almost code complete on the Kolibri smart contracts, but we need to perform a security audit and finish the web frontend that will make it easy for anyone to mint kUSD. We plan on launching on testnet before the end of the year, and after the security audits are complete, launch on mainnet soon afterwards. After launch, we’d also like to explore support for more types of collateral than just tez, such as wrapped Ethereum and Bitcoin, and eventually build a decentralized lending platform where participants can supply or borrow all types of assets.

What led you to build on Tezos? Why not create these projects on a different blockchain?

Tezos has a strong ecosystem of over 400 proof of stake validators that help secure the network, and the network is able to upgrade itself through on-chain governance to support new features. In addition, Tezos’ liquid proof of stake architecture enables tez holders to stake and earn rewards for helping to secure the network, while remaining fully liquid and having the ability to send their tez to another address or contract even while it is staking. This enables staked tez to have more utility than staked assets on other blockchains, where those assets are unusable while staking. In addition, we’d like to thank the SmartPy team for making an excellent smart contract language that enabled us to write unit tests and debug smart contracts in a browser. Without SmartPy, creating Harbinger and Kolibri would have been much more challenging.

What three things are you most excited to see built on Tezos?

We’d love to see lending platforms evolve and flourish. We’d also like to see on-chain DAOs (decentralized autonomous organizations) implemented on Tezos and be used to fund new protocol feature development for the broader Tezos ecosystem. In addition, We’d like to see new types of decentralized exchanges that provide pricing functions that are more preferable for stablecoins.


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