SNARK-powered DeFi: Teller builds decentralized lending dapp using Mina

Mina Protocol
Published in
3 min readApr 10, 2021


Teller Finance, an algorithmic credit risk platform, is building a decentralized lending market using Mina Protocol technology, to pioneer a new generation of DeFi dapps that will allow users to access critical on-chain services without sharing their personal data.

Teller’s new DeFi platform, built using Mina’s Snapps, means you can prove that your credit score is above a certain threshold, according to a trusted source such as Credit Karma. Your actual score is not visible to Teller (or anyone else), and there’s no need for you to share private information, such as your social security number.

Not only does this breakthrough eliminate the risk of personal data vulnerabilities, it also opens up the possibilities of unsecured lending — a fundamental part of traditional finance — in the DeFi space. Mina’s technology enables DeFi users to take out loans without supplying collateral, and remain in control of their private data, helping to create a fairer and more secure financial ecosystem. This unlocks the potential for a huge new wave of lending on DeFi protocols.

Mina’s SNARKs offer a new dimension to DeFi

On other blockchains, counterparties receive actual user data, and blockchains that tout privacy features often require users to share their data with a trusted enclave (a blackbox hardware solution) — but these are known to have vulnerabilities and can leak data when they fail.

On Mina, counterparties receive proofs — not the data itself, thanks to Mina’s use of zk-SNARKs (zero knowledge proofs). Users never have to share their data with anyone or any entity. Instead, only the user’s local machine can access their data to create a proof.

The Teller partnership is a great example of the unique power of Snapps built on Mina. No other blockchain can trustlessly and privately bring data on-chain like Mina.

SNARK-powered dapps: How do they work?

A SNARK-powered dapp (Snapp) connects to a source website and produces a zero knowledge proof related to data on that website. The proof reveals only the fact (i.e. the user’s credit score passes the threshold), not the data itself.

The Snapp shares the proof with the Mina network and can then sends the verified proof to Teller via an encrypted transaction. Watch our demo below to see Teller’s credit score Snapp in action:

Mina’s partnership with Teller is the first proof point for a viable credit score dapp that protects its users’ personal data, and soon users will be able to connect to other websites to prove their score, and much more.

Any users who wish to test out the flow should visit, click on Borrow, then Unsecured Loans and follow the demo instructions. (Here is the instructional video which walks you through the steps.)

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