Amaury Séchet

Little verified information is public about the childhood of Amaury Séchet, and he has generally kept personal details out of view even while maintaining a loud presence in technical debates. He is French, and before entering the cryptocurrency world he built a reputation as a systems programmer with a strong interest in language design and compiler engineering ^[1].

Within the D programming language community he became known under the handle deadalnix, contributing to discussions on language semantics and starting his own compiler project, the Snazzy D Compiler, usually shortened to SDC ^[1]. That work gave him credibility among low level programmers well before Bitcoin made him a public figure, and it shaped the blunt, engineering first style he later brought to cryptocurrency development.

Anyone researching an Amaury Séchet biography quickly notices this gap between his private and public lives: his birth date, family background, and education are not reliably documented in mainstream sources, while his software output and public statements from 2017 onward are extensively recorded ^[2].

Séchet worked as a software engineer at Facebook, where he was involved in infrastructure level engineering during the period when the company invested heavily in high performance PHP tooling ^[2]. He has said in interviews and public talks that he left the company to work on Bitcoin full time as the block size debate intensified ^[2].

That debate defined the era he entered. Between roughly 2015 and 2017, the Bitcoin community argued bitterly over whether the network should raise its one megabyte block size limit to allow more transactions per block, or keep blocks small and scale through second layer systems. Séchet sided firmly with the large block camp, arguing that Bitcoin should function as inexpensive peer to peer electronic cash rather than primarily as a settlement layer ^[3].

For readers asking who was Amaury Séchet in this period, the answer is a relatively unknown engineer who chose an unusually direct route into the argument: instead of lobbying existing developers, he wrote his own full node implementation. In June 2017 he presented Bitcoin ABC (Adjustable Blocksize Cap) at the Future of Bitcoin conference in Arnhem, in the Netherlands, announcing software that would reject the SegWit upgrade and accept larger blocks ^[3].

On 1 August 2017, nodes running Bitcoin ABC split from the Bitcoin network, creating a new chain with an eight megabyte block size limit. The result was Bitcoin Cash (BCH), which instantly became one of the largest cryptocurrencies by market value because every holder of Bitcoin received an equal balance on the new chain ^[4]. The event was covered by major financial press as the most significant fork in Bitcoin's history to that point ^[4].

Séchet served as the lead developer of Bitcoin ABC, which functioned as the reference implementation for Bitcoin Cash. In that role he coordinated the network's scheduled protocol upgrades, which the project ran twice a year, and he pushed through technical changes including a new difficulty adjustment algorithm and the reintroduction of expanded script capabilities ^[5].

Among Amaury Séchet achievements, the launch itself remains the most consequential: few individual engineers have initiated a chain split of that scale. Supporters credited him with giving the large block movement working software rather than endless argument. Critics, including many Bitcoin Core supporters, viewed the fork as an unnecessary fracture of the network. Séchet never showed much interest in softening either reaction, and his combative posts became a fixture of cryptocurrency social media ^[2].

In November 2018 Bitcoin Cash itself split. A faction led by Craig Wright and the mining firm CoinGeek backed a rival client called Bitcoin SV, opposing changes that Bitcoin ABC had scheduled, including canonical transaction ordering. The confrontation became known as the hash war, as each side directed mining power at its preferred chain ^[6]. The ABC side, supported by figures such as Roger Ver and the mining company Bitmain, retained the Bitcoin Cash name and ticker, while Bitcoin SV continued separately ^[6].

The episode confirmed Séchet's position at the center of Bitcoin Cash decision making, and that centrality soon became its own controversy. In 2020 he backed a proposal known as the Infrastructure Funding Plan, which would have redirected eight percent of newly mined coins to fund protocol development, primarily Bitcoin ABC ^[7]. Much of the Bitcoin Cash community rejected the idea as a developer tax that contradicted the currency's ideals.

The disagreement produced a second split on 15 November 2020. The majority of the ecosystem followed a new client, Bitcoin Cash Node, and kept the BCH name. The minority chain running Séchet's software continued under the ticker BCHA ^[7]. It was a costly outcome for him in influence and reputation, yet he kept building on the smaller chain rather than conceding.

In July 2021 Séchet rebranded the BCHA chain as eCash, with the ticker XEC, redenominating the currency so that one old coin became one million new units ^[8]. He framed the project as a return to the original goal of electronic cash, borrowing its name from the digital money concept associated with cryptographer David Chaum decades earlier ^[8].

Technically, eCash under Séchet's direction pursued an unusual hybrid design: it kept Bitcoin style proof of work while layering Avalanche consensus on top for fast finality and improved coordination between nodes. The Avalanche post consensus system went live on the eCash network in 2022 ^[9]. The roadmap he published also included staking rewards for Avalanche participants, which were activated in a later upgrade ^[9].

Séchet remains a working programmer rather than a figurehead. His commits, technical writing, and long form posts continue to appear under the deadalnix name, and he still argues publicly, often abrasively, with critics of his design choices ^[2]. As a living person whose main record is code and public commentary, the basic Amaury Séchet facts are best checked against the project's own documentation and contemporaneous press coverage rather than secondhand summaries.

Séchet's place in cryptocurrency history is secure even though its interpretation is contested. He demonstrated that a determined engineer with a working client could split the largest blockchain in the world, a precedent that reshaped how the industry thinks about protocol governance, miner signaling, and the power of reference implementations ^[4]. Bitcoin Cash, whatever its later fortunes, forced exchanges, wallets, and businesses worldwide to build processes for handling chain splits.

His career also illustrates the limits of that power. Twice, communities he helped build moved against him: first the Bitcoin SV faction in 2018, then the Bitcoin Cash majority in 2020. Each rupture shrank the network he led while leaving him free to pursue his own technical vision with fewer constraints ^[7].

Among developers he is respected for genuine engineering depth, from compiler internals to consensus design, and criticized for a governance style that concentrated decisions in his own hands. Journalists covering the scaling wars regularly described him as one of the era's most consequential and most polarizing figures ^[2]. Whether eCash ultimately succeeds or not, any honest account of how Bitcoin fractured and evolved between 2017 and the early 2020s has to reckon with his work.