How simstim compares

There are many ways to keep a coding agent working while your laptop is closed. This page says where simstim fits among them, and when another tool is the better choice. The facts come from the competitor research, read on 15 October 2026, which has a source for each one. Products change fast: in 2025 and 2026 several shut down, changed their licence or changed hands.

What simstim is for

simstim runs any terminal agent in a session on a Linux host you own, and passes the agent’s own screen to your terminal byte for byte. Four things together make it different:

1. Any agent. Claude Code, Codex, opencode, Antigravity CLI or any other terminal program. Agents are rows in a table, not code paths.
2. The real terminal UI. No multiplexer or web page re-draws the screen, so the kitty keyboard protocol, truecolour, OSC 8 links, OSC 52 clipboard and desktop notifications work as they do locally.
3. Sessions that last. They survive sleep, a change of network and a host reboot, and you get back exactly the output you missed.
4. Your own machines. Any host you can reach with ssh. No account, no relay, and no new open port.

The research found no other tool with all four.

Terminal multiplexers: tmux, Zellij, screen

The classic way: start the agent inside tmux on a server, and reattach over SSH.

• They re-draw the screen. A multiplexer keeps its own model of the terminal and draws that, not the agent’s bytes. Its scrollback replaces your terminal’s, so Cmd+F finds nothing. tmux 3.8 has no kitty keyboard protocol, so Shift+Enter arrives as Enter.
• Their prefix keys clash with the agents’ own keys.
• They know nothing about agents. No status, no “needs input”, no resume after a reboot.

Choose a multiplexer if you want split panes on the host, or already live in tmux and do not miss the things above. simstim does not split panes; your terminal can.

Pass-through session tools: zmx, Eternal Terminal, mosh

zmx and Eternal Terminal pass the bytes through and survive a dropped connection, much like simstim does. mosh predicts your typing on slow links.

• zmx and Eternal Terminal lose their sessions when the host reboots, and they do not manage agents.
• mosh has no kitty keyboard protocol, no scrollback and no OSC 9 or 777 notifications.

Choose mosh for a very slow or lossy link, where its local echo matters more than fidelity.

Hosted agents

Amp, Claude Code cloud sessions, Codex cloud, Cursor cloud agents, Jules, Devin, Factory and Warp run an agent for you on the vendor’s machines, in a web or app UI.

• One vendor’s agent in each, in the vendor’s own interface rather than the agent’s terminal UI.
• Limits and plans. Several cap session length or parallel tasks, or need a paid plan for background work.
• They give you more out of the box: a phone or web client, sharing with a team, and a fresh sandbox for each task.

Choose a hosted agent if you want to start tasks from your phone or browser, share them with others, or never run a machine yourself.

Vendor agents on your own machine

Several vendors now run their agent on a machine you own, with their control plane: Amp runners, Claude Desktop’s SSH sessions, Codex’s SSH hosts, Cursor’s My Machines, Devin Outposts, and Factory’s and Warp’s Remote Control.

• The machine is yours, but the account, the agent and the interface are the vendor’s.
• Each works with one agent.

Choose one of these if you use a single vendor’s agent and want its app on every device.

Cloud development environments: Coder, Codespaces, Daytona, DevPod

These give each developer a workspace on a server, and you reach it with SSH or an editor.

• Workspaces stop when idle, and a session needs tmux to survive a disconnect, which brings the multiplexer’s limits back.
• Coder’s agent features now need its own agent and API keys. DevPod has stalled. Daytona went closed source in June 2026.

Choose a cloud development environment if a team needs the same workspace templates, access control and audit across many people.

Where simstim is behind

simstim is young, and some things are missing on purpose or not yet built:

• No phone or web client. You need a terminal. An alert can reach your phone (alerts), but you answer from a terminal.
• No sharing. A session belongs to one user’s account on the host.
• You bring the host. host create can make a local VM, a test container or an E2B sandbox (create a host); for anything else you need a Linux host with SSH.
• Isolation is per worktree, not per machine. Each task can have its own branch and folder (worktrees), but tasks on one host share it.
• Not released yet.

Summary