Dev who gave HashiCorp its name returns with a faster terminal multiplexer

DEVOPS

Persistent sessions could be just the beginning

HashiCorp cofounder Mitchell Hashimoto has launched a new startup to build a server-side terminal multiplexer that allows programmers to switch between multiple persistent work sessions.

Superlogical promises its terminal multiplexer will be faster and keep better track of user jobs. And it could be instrumental to building durable agentic layers into future systems. 

The problem with traditional multiplexers – such as tmux, Zellij and GNU Screen – is that they are all too slow, explained Superlogical cofounder Mitchell Hashimoto in a video posted on X. They duplicate everything the user types and have to constantly reconcile local and remote states. Even slapping a modern terminal such as Kitty, Alacritty or Ghostty in front of a multiplexer won’t do much to speed ops.  

“A terminal multiplexer may sound like a narrow place to start a company,” the company admits on its website. But the lowly terminal is the common denominator across today’s developers, agents, tools, and infrastructure. 

For Hashimoto, today’s computer architecture is missing a fundamental primitive: a stateful session for the work itself. With work spanning machines and users, a task needs its own space for context, data, and history.  

Turning a terminal into a business

The technology builds on a project called Ghostty, a modern terminal emulator that Hashimoto began developing while he was still at HashiCorp, the company he co-founded.

One of the oldest tools in the computer stack, a terminal emulator is simply a text-based window on the screen where developers can enter commands for the computer, either locally or remotely. Taking its name from the physical terminals of a bygone era, the terminal is where one finds the “command line interface” or CLI. 

The terminal geeks quickly and widely adopted the GPU-driven Ghostty for both its lightning-fast performance and wealth of features – two qualities other emulators rarely possessed in tandem.

Hashimoto also extracted the core Ghostty engine into its own software library, libghostty, for others to build upon. Superlogical plans to eliminate that client/server duplication by building on libghostty.

In Superlogical’s approach, the client sends terminal input to the server, much like an SSH session, while the server maintains the persistent session state. This lets users disconnect and return later, while a smart client handles rendering and scrolling locally rather than waiting for a network round trip.

“It does require that every connecting client be a very smart, high-functioning, compliant client,” such as one built on libghostty, Hashimoto said. But this approach sounds better than dispatching streams of raw ASCII hither and yon.

Beyond describing the headaches of multiplexers in his introductory video, Hashimoto didn’t divulge much more about the newly founded company’s plans, but the mission will no doubt involve expanding on the concept of managing work sessions in a standardized and scalable way. 

Gergely Orosz, author of the popular Pragmatic Engineer Substack, speculated on X that the Superlogical team would “be building an AI-native ‘agentic operating system’ that sits a level above OSes.” ®