Jujutsu's Creator Left Google for a Startup. Its Tools Got a Conference.

The Git alternative Jujutsu, usually shortened to jj, spent 2026 gaining a commercial backer and a fan-built tool ecosystem large enough to fill its own conference talk. On Sept. 1, the startup East River Source Control announced that jj's creator, Martin von Zweigbergk, had joined as chief technology officer after 15 years at Google, where he started jj as a side project in late 2019 before it became his full-time work. Fifteen days later, at JJ Con 2026 on Sept. 16, developer André Arko catalogued dozens of tools built around jj by people who don't work for either organization.

What jj actually is

Jj is a version control system, meaning it tracks changes to a codebase the way Git does, but it is designed to interoperate with Git repositories rather than replace them outright: a team can keep pushing to and pulling from an ordinary Git remote while individual developers use jj locally. The project lives at github.com/jj-vcs/jj, moved to that independent GitHub organization in December 2024, carries an Apache 2.0 license, and has 31,676 stars as of Sept. 21, 2026.

Why a startup wants to sit on top of it

Von Zweigbergk's new employer is explicit that jj alone doesn't solve the problem it's building for. "Jujutsu improves the part of version control that sits on your laptop," he said in ERSC's announcement. "But the remote server is still Git, which has a ceiling that comes fast for products at scale." ERSC, backed by Amplify Partners, is building server-side version control infrastructure aimed at organizations it says have outgrown a plain Git remote, and its first product, ERSC Storage, enters private beta later in September 2026. Chief executive Benjamin Brittain framed the hire in similarly practical terms: "The hard problems many engineering teams are just beginning to face are ones he's already been working on for over a decade." Von Zweigbergk remains a core maintainer of jj as an open-source project, so the arrangement pairs a commercial server product with a client that stays free and independently governed.

What Arko's talk found already built

Arko's JJ Con 2026 survey, delivered under the title "beyond jj: config & tools ecosystem," split the landscape into jj's own newer built-in commands, among them jj bisect run for finding a regression without an external script and jj absorb-adjacent features like jj arrange for interactive graph reordering, and a much larger layer of independently maintained software. That outside layer includes desktop GUIs such as gg, a Rust and Tauri app, and jjewel, a native macOS client with drag-and-drop graph editing; terminal interfaces including lazyjj and jjui; and editor plugins reaching VS Code, JetBrains IDEs, Vim, Emacs and Helix. On the hosting side, Arko pointed to GitHub's stacked-PR support, the peer-to-peer forge Radicle, and Tangled, an ATProto-based forge he said offers "full support for jj" including change-ID tracking, as the three forges that already build jj-aware review flows on top of a system whose canonical home is still a Git server.

What the talk didn't include

Arko's post catalogs tool names and what each does, but it does not publish a total tool count, a timeline of when the ecosystem started forming, or any download or install-base figures for jj itself, so how many working developers this actually reaches, rather than how many projects have been started, is not something either JJ Con or von Zweigbergk's new employer has put a number on. The 31,676 GitHub stars measure attention to the core project, not the size of the plugin economy built around it.

Layer (per Arko's JJ Con 2026 talk)	Examples named
Built-in jj commands	bisect run, run, fix, tag, arrange, converge
Desktop GUIs	gg, jayjay, lightjj, jjewel, weiff
Terminal UIs	lazyjj, jj_tui, jj-fzf, jjui, majjit
Forge integrations	GitHub stacked PRs, Radicle, Tangled, JJHub

Source: andre.arko.net, accessed Sept. 21, 2026.

A commercial bet on a Rust-based tool stack is not unique to version control in 2026. Microsoft made Rust a tier-1 language alongside C++ and C# in a move covering more than 100 of its own repositories, and the browser engine Servo, also written largely in Rust, has been sustaining itself through a year of donor-funded maintainer work rather than a corporate backer. Jj's path, an open client plus a for-profit server company built by the same person, is a third funding model that neither of those two examples quite matches, and it carries its own risk: if ERSC's paid product becomes the main reason to keep funding jj's maintenance, the client's development pace could end up tied to a single startup's fortunes despite the Apache 2.0 license technically permitting anyone else to pick up the work.

What happens if ERSC's bet doesn't pay off

Nothing in either announcement addresses that scenario directly. Von Zweigbergk's title change came with no announced commitment on how many hours a week he'll spend on jj's open-source maintenance versus ERSC's paid server product, and the company's own post frames his jj work as continuing rather than winding down. The clearest test will be the cadence of jj's own releases over the months after ERSC Storage leaves private beta: a slowdown would suggest the open client is now secondary to the company built on top of it, while an unchanged pace would support von Zweigbergk's framing that the two efforts are complementary rather than competing for his time.