The origin story of Ethereum’s most important crypto wallet – MetaMask – may be headed to court.

In a lawsuit filed in state court in San Francisco on Tuesday, Joel Dietz, an entrepreneur who says he spearheaded early efforts to build a browser-based digital wallet, accused the Ethereum-focused developer firm Consensys of writing him out of its history and stealing his share of its treasure.

MetaMask is the world’s most widely used crypto wallet and the powerhouse asset of Ethereum co-founder Joseph Lubin’s Consensys, a company last valued at $7 billion in early 2022. MetaMask was created in 2016 by Consensys employees Aaron Davis and Dan Finlay, according to the company.

But, according to Dietz, he created the intellectual property that he says became MetaMask in late 2014, when he founded a project called Vapor. In his lawsuit, he accuses Davis, whom he says he hired in 2015 to help code Vapor, of betraying him and conspiring instead with Consensys.

A Consensys spokesperson said: “Joel Dietz is an individual we understand to have been falsely marketing himself as the founder of MetaMask in an attempt to sell tokens or gain investment from unsuspecting investors globally. Joel Dietz is not a founder of MetaMask, has no relation to MetaMask or any of its technology and we look forward to the court promptly disposing of these frivolous claims. MetaMask was founded by Aaron Davis and Dan Finlay in 2016. The origin story of how MetaMask came to life is publicly available here.”

The history of Dietz’s Vapor is entangled in Ethereum’s earliest days. In an interview with CoinDesk, Dietz said he came up with the vision for an in-browser crypto wallet more than half a year before the blockchain went live in July 2015.

Even then, Dietz said he was a fan of Ethereum’s potential to host software programs that anyone could use on a decentralized platform that no one could stop. But he thought it needed a wallet through which people might navigate this universe right from their browser, instead of first downloading a clunky, separate app.

Dietz said he pitched Vapor to key Ethereum figures Vitalik Buterin and Gavin Wood in November 2014 “and got an initial sign-off from them” to build it, plus encouragement from Buterin to seek a grant from their Ethereum Foundation. He said he did so in March 2015, having brought on two partners, Martin Becze and Aaron Davis.

Within this group, Dietz fashioned himself as the product’s visionary, spokesperson and fundraiser, while Becze and Davis were its primary coders, according to the lawsuit. He said they planned to build it as an open-source project but had a road map to eventually monetize it by imposing fees on users who swap between different cryptocurrencies within the app.

(Under Consensys, MetaMask has generated over $220 million in swap fees, according to one estimate of its lifetime revenue.)

But the $30,000 they received from the Ethereum Foundation in early 2015 barely funded two months of work on Vapor; other fundraising efforts, including an application to join the storied accelerator program Y Combinator, didn’t pan out.

By May, Dietz seemed to think Vapor was losing momentum and, not hearing anything to prove otherwise from Davis, the developer, he shifted his focus to other ventures. Dietz didn’t think much of it when Davis nixed his access to their shared Slack server and GitHub repositories; as far as he was concerned, Vapor and its vision to build an in-browser crypto wallet was dead.

One year later, Consensys debuted MetaMask, the Chrome browser extension that made it easy for anyone to send, spend and swap cryptocurrencies on the Ethereum blockchain. It credits Davis as one of the app’s founders, but has never mentioned Dietz.

According to Dietz, Consensys has gone to great lengths to suppress his involvement in MetaMask’s creation. He alleges the company threatened a journalist whose article described Dietz as the founder of MetaMask in November 2021.

At this point, Dietz said he pieced together “the exact relationship” linking his Vapor and Consensys’ MetaMask, and became convinced that he had been wronged. The way he saw it, Ethereum’s insiders had pulled “an elaborate internal rug pull” on him.

“These were things that Vitalik specifically asked me to do – and then they just never compensated me at all for anything,” he said. “So, it feels kind of like a rigged insider game.”

He added: “I’m confident that the case will show the substantial evidence that proves my role as a founding partner of MetaMask, and I know several colleagues in our community will verify that.”

UPDATE (Aug. 2, 2023, 18:13 UTC): Adds an additional comment from Dietz in the final paragraph.