Over the years Ethereum's co-founder Vitalik Buterin has pointed to Kleros again and again. Decentralized courts, curated lists, proof of personhood, crypto + AI, d/acc, and the talent coming out of Argentina. The richest vein is his own blog, where Kleros turns up in ten essays, with the seed idea going back to 2014. Here are the moments, with the receipts.
The most recent one. When Kleros launched Foresight (a prediction market where the crowd predicts a critic's movie scores, built on Seer + Gnosis Chain), Vitalik reposted the announcement to his followers. The tweet leans directly on his own "distilled human judgement" idea (the info-finance concept). Verified live: vitalik.eth sits at the top of the post's reposters.
Maybe the warmest one. In the thread of his "d/acc: one year later" essay, Vitalik replied to a tweet from us (@jnptzl) and @Kleros_io connecting Kleros to d/acc's "info defense (eg. anti-scams)" quadrant. He agreed, and credited Kleros directly.
Floating the idea of decentralized forums moderated by Kleros, Vitalik cited the protocol's ruling on a court case asking who won the 2020 US election (dispute #532) as proof the system reaches sane outcomes.
Listing the pieces he sees as core to the cypherpunk vision for Ethereum, Vitalik named Kleros as the example for decentralized courts, next to DAI, Uniswap, Augur and ENS.
During his visit to Buenos Aires, Vitalik praised the projects coming out of Argentina, naming Kleros alongside Proof of Humanity, OpenZeppelin and Nomic Labs, and spoke about how struck he was by the country's growing Ethereum developer community.
“He commended projects of Argentinean origin like Nomic Labs, Proof of Humanity, OpenZeppelin, and Kleros, noting the amazing talent in the country and how amazed he was by the growing Argentinian Ethereum community.
— reported from Vitalik's Buenos Aires talk, December 2021
In his ETHNewYork keynote, when the question turned to how a protocol could maintain a curated registry — deciding which entries (e.g. real humans vs. bots) belong on a list — Vitalik's answer was simply to use Kleros. The line became a small piece of Kleros lore. This is the curation / Curate-adjacent mention.
“Just use Kleros.
— Vitalik Buterin, ETHNewYork keynote, 2019
Two indirect but real ties. Kleros openly builds on Vitalik's credible neutrality framework (his 2020 essay). And in July 2021 Vitalik joined Proof of Humanity — the anti-sybil registry whose human verification runs on Kleros curation — by submitting his own profile.
On his blog · the idea, and ten essays
The seed. Four years before Kleros launched, Vitalik described a mechanism where people independently vote on an answer and are rewarded for matching everyone else, a Schelling-point game that pulls honest jurors toward the truth. It does not name Kleros (nothing did yet), but it is the direct intellectual ancestor of how Kleros jurors vote.
“Everyone wants to provide the correct answer because everyone expects that everyone else will provide the correct answer and the protocol encourages everyone to provide what everyone else provides.
— Vitalik Buterin, "SchellingCoin", Mar 2014
This is the post you were thinking of. Vitalik opens with Kleros as one of three motivating examples of decentralization, defines it as a decentralized court, and frames it as exactly the kind of subjective-oracle / human-judgement engine that prediction markets and info-finance ultimately lean on.
“Kleros is a "decentralized court": a DAO whose function is to give rulings on arbitration questions such as "is this Github commit an acceptable submission to this on-chain bounty?" Kleros is all about making unavoidably subjective judgements on any arbitrary question that is submitted to it.
— Vitalik Buterin, "DAOs are not corporations", Sep 2022
“The "decentralized court" system Kleros is a really valuable and important piece of infrastructure for the Ethereum ecosystem: Proof of Humanity uses it, various "smart contract bug insurance" products use it, and many other projects plug into it.
— same essay, "Fairness in Kleros" section
Reviewing crypto's hardest open problems, Vitalik points to the Kleros token-curated registry twice: as the best example of progress on reputation systems, and as an instance of a working decentralized oracle, alongside Augur. The curation angle you remembered lives here.
“The best is the use of token curated registries to create curated lists of trustable entities/objects; the Kleros ERC20 TCR (yes, that's a token-curated registry of legitimate ERC20 tokens) is one example, and there is even an alternative interface to Uniswap that uses it as the backend.
— Vitalik Buterin, on reputation systems
“The largest known instance of a decentralized oracle running is Augur... Token curated registries such as the Kleros TCR for tokens are another example.
— same essay, on the oracle problem
Arguing which systems most need to be robustly decentralized, Vitalik lists Kleros among the "meta-DAOs" that provide services to other DAOs and that people increasingly rely on day to day.
“...for "meta-DAOs" that provide services to other DAOs: Proof of Humanity, Kleros, Chainlink, Stablecoins, Blockchain layer 2 protocol governance.
— Vitalik Buterin, Dec 2022
His deepest write-up on how Kleros actually works. A whole section, "The central role of collusion in understanding the difference between Kleros and regular courts," walks through the conformity incentive and the fork-as-final-backstop, using the same Biden/Trump example he'd tweeted about.
“The theoretical answer to this is the right to exit: if the majority of Kleros jurors vote to proclaim that Trump won the election, a minority can spin off a fork of Kleros where Biden is considered to have won.
— Vitalik Buterin, Sep 2021
Sketching how crypto and AI combine, Vitalik reaches for Kleros's multi-round escalation design as the template, with AIs handling the early rounds.
“You don't even need the humans to adjudicate most questions: you can use a multi-round dispute system similar to Augur or Kleros, where AIs would also be the ones participating in earlier rounds.
— Vitalik Buterin, Jan 2024
Discussing how proof-of-personhood systems handle challenges, Vitalik puts a Kleros court at the center of the dispute path.
“If there is a challenge, a Kleros decentralized court determines whether or not your video was genuine; if it is not, you lose your deposit and the challenger gets a reward.
— Vitalik Buterin, Jul 2023
Shorter mentions where Kleros shows up as the go-to example for arbitration, escalation, or Argentine builders.
"Argentinians punch above their weight in projects like Proof of Humanity, Kleros and Nomic Labs." ↗ source
On Proof of Humanity revocation: "a Kleros court decides whether or not the video was from the same person as the original creator." ↗ source
Listed under decentralized-governance primitives: "Escalation games: see Augur and Kleros." ↗ source
On fighting impersonation: "if one wishes for a more decentralized solution one could try using Kleros or some similar system." ↗ source
Vitalik's "From prediction markets to info finance" (Nov 2024) does not name Kleros directly. But the idea you're remembering is real and runs right through his thinking: info finance is "distilled human judgement," and he has repeatedly warned that a prediction market is only as good as its oracle, pushing for decentralized oracles with private voting. Kleros is precisely that subjective oracle (the "unavoidably subjective judgements" engine from the 2022 post above) and now powers prediction-market arbitration via Kleros Foresight (Seer → Reality.eth → Kleros Court). Worth noting: in the 2025-2026 oracle debate he actually cites UMA's token-voting model as the thing to improve on, not Kleros, even though his "decentralized oracle + private voting" ask describes Kleros's sortition + commit-reveal almost exactly. If you find a post where he names Kleros in the InfoFi context, send it and I'll add it.