Herder: The Open-Source Terminal Tool for Unified Management of Multiple AI Coding Agents

The Real Pain of Running Multiple AI Coding Agents Simultaneously

If you're the kind of power user who runs Claude Code, Codex, OpenCode, and other coding agents all at once, you know the struggle all too well: six, seven, or even eight terminal windows open on your desktop at the same time. Not only do you have to watch the progress of every task, but you also have to figure out which agents are working, which have gotten stuck, and which need your attention first. Worse still, one careless click to close a window can wipe out a task that was only halfway done.

It's worth clarifying up front what AI Coding Agents are: they're a category of development tools that have rapidly emerged over the past couple of years. They can understand natural-language instructions, autonomously read through codebases, write and modify code, and even run tests and debug. Unlike traditional code-completion tools (such as the early versions of GitHub Copilot), agents have far greater autonomy and multi-step reasoning capabilities, able to complete the entire pipeline from requirement analysis to code commit within a single task. Claude Code is a command-line coding agent released by Anthropic, Codex stems from OpenAI's code-generation model lineage, and OpenCode is an open-source community alternative. Most of these agents use the terminal (CLI) as their interface, because the terminal environment is lightweight, scriptable, and easy to integrate with development toolchains like Git and build systems. Precisely because each agent typically occupies its own terminal process, power users run into the aforementioned "window explosion" dilemma when handling multiple tasks in parallel.

To address this pain point, an open-source tool called Herder offers an elegant solution. It's a Terminal Multiplexer that lets you control multiple terminals and multiple AI coding agents from a single unified interface. It's lightweight enough, supports both macOS and Windows, and installs with just a single command.

The Three Core Values of Herder

Herder primarily brings three things: organization, observability, and persistence.

Organization: Say Goodbye to Terminals Scattered Across Your Desktop

The most immediate benefit is organization. Instead of a pile of terminal tabs scattered across your desktop, Herder can display multiple agents simultaneously within a single space. For example, two Claude Code terminals side by side at the top, OpenCode in the bottom left, and Codex in the bottom right—all at a glance.

Its organizational hierarchy is remarkably clear:

• Spaces: The top level, which you can think of as a "project" or workspace folder. You can create and rename them at any time—for instance, setting up a space called "Web Design."
• Tabs: Sub-categories within each space, similar to tabs in a regular terminal, used to organize different subtasks within a project. For example, the first tab for research, the second for running a development server.
• Panes and Agents: Within each tab, you can right-click to "split right" or "split up/down," allowing any number of agents to work simultaneously.

It's worth mentioning that Herder isn't purely keyboard-driven—many actions can be performed directly with mouse clicks, making it very beginner-friendly.

Observability: See at a Glance Who's Running and Who's Stuck

In the Agents tab on the left, Herder tells you precisely which agents are working, which have finished, and which are stuck waiting for your input. A moving "little yellow snake" indicator appears next to running agents, making their status clearly visible.

This is especially useful in scenarios where agents collaborate with each other. The author demonstrates a typical workflow: have Claude Code draft a plan, then use the Codex Review skill to send that plan to Codex for review. Codex raises questions, Claude revises the plan, and the two iterate back and forth until they converge on an agreed solution.

The "headless" execution mentioned here refers to a program running in the background without a visual interactive interface. In AI agent collaboration scenarios, one agent often invokes another in headless mode to complete a subtask—for example, Claude Code sending its generated plan to Codex for review via the Skill mechanism. This "agent reviewing agent" pattern borrows from the code review practice in software engineering: introducing a second independent model's perspective helps uncover blind spots, reduce hallucinations and logical flaws, and thereby improve the reliability of the final output. However, the natural drawback of headless collaboration is opacity: users can only see the final result and cannot observe the intermediate reasoning and back-and-forth.

But in Herder, the entire back-and-forth interaction is visible in real time—you can see all the challenges Codex raises about the plan, as well as Claude's revised, adjudicated version. This essentially turns "black-box collaboration" into "glass-box collaboration," allowing developers to trust the automation while still being able to step in and correct course when necessary.

Persistence: Tasks Keep Running Even After You Close the Window

The third point—and the author's favorite feature—is persistence. Herder essentially acts as a background server, so even if you completely exit the terminal window, your running tasks won't be interrupted.

This capability actually stems from the classic technical principle of terminal multiplexers. A terminal multiplexer is a type of tool that lets you run and manage multiple terminal sessions within a single terminal interface, a concept dating back to GNU Screen and later the more popular Tmux. Their core technique lies in the "separation of session and client": the multiplexer maintains a persistent server process in the background that hosts all terminal sessions (pseudo-terminals, or PTYs), while the front-end client is merely a display layer connected to that server. This architecture brings two key advantages—first, you can split the screen into multiple panes displaying different sessions simultaneously; second, even if the client disconnects (e.g., an SSH connection drops or the window closes), the background sessions keep running and can be seamlessly restored upon reconnection. Herder follows exactly this classic architecture and layers an AI-agent state-tracking system on top of it.

In the demo, the author exits the entire terminal while two agents are working, then reopens PowerShell and types herder—and the previous tasks are still running, exactly as they were. This means as long as your computer stays on (closing the laptop lid without going to sleep works too), your agents can keep running for any length of time. Better yet, you can even reconnect via your phone or SSH to sessions running in the background.

How Does Herder Differ from Tmux and Cmux?

Readers familiar with terminal tools might ask: how is this different from the long-established Tmux, or from Cmux?

Compared to Tmux: Tmux also essentially lets you control all your terminals from one place, but it lacks out-of-the-box Agent Forwarding capabilities. Herder's Agents tab on the left is dedicated to tracking the running status of each agent, letting you easily manage five, six, seven, or even more agents than the eye can track—something Tmux can't do.

Compared to Cmux: The biggest differences come down to two points—first, Herder's persistence philosophy (keeps running in the background after exit, with remote reconnection), and second, Herder can be used very easily on Windows, making it cross-platform-friendly.

Herder Installation and Usage Guide

Installing Herder is extremely simple, requiring just a single command. Visit the official website at herder.dev or Herder's GitHub page, copy the installation command shown, and paste it into your terminal to run.

Once installed, simply type herder in your terminal to launch it. The interface presents three sections: Spaces, Agents, and the actual terminal. It works just like a regular terminal—type claude to fire up Claude Code, or type other commands to launch the corresponding agents.

Agent Skills and the Plugin Marketplace

An advanced highlight of Herder is Agent Skills. Through Herder skills, you can teach agents how to use Herder themselves—meaning an agent can automatically create new panes and new spaces within Herder, so you don't have to do all the organizational work manually. Let the AI manage its own workspace.

In addition, Herder has a complete plugin marketplace. The community has already begun developing various add-ons for it, and the ecosystem is growing rapidly.

Keyboard Shortcuts and Personalization Settings

In the settings menu, you can change the theme, sounds, toast notifications, tab integrations, and experimental features. As for keybindings, Herder's logic is similar to Tmux, using a "prefix mode": first press Ctrl + B as the prefix, release it, then press a specific key to execute the action (e.g., V for a vertical split). Of course, the vast majority of operations can also be done through the right-click menu.

Conclusion: A Terminal Workbench for the Multi-Agent Era

Herder's true value lies in its unified management capabilities when you need to run multiple agents simultaneously across different programming frameworks. As the author notes, the agent view inside Claude Code is excellent, but it only works within Claude Code. In real-world development, we often mix Codex, open-source agents, and various other tools—and Herder's observability and organization capabilities fill exactly this gap.

Add to that the reassuring persistence feature—finally putting an end to the awful experience of "exiting the terminal and losing your task"—along with its open-source, free, cross-platform (Windows/macOS) nature, and Herder is well worth a try for every multi-agent power user.

Note: This article is compiled based on related Bilibili video content, presented as a single-source introduction. Refer to the official documentation for specific features.

Key Takeaways