# Otter

> Experimental JS runtime with ability to run 1k+ threads - gi-dellav/otter

- **Website:** https://github.com/gi-dellav/otter
- **Pricing:** unknown
- **Categories:** Developer Tools, Productivity
- **Tags:** developer-tools, productivity, design
- **Platforms:** CLI
- **Last verified:** 2026-09-10
- **Canonical page:** https://linkrena.com/tools/otter

## About

worker threads — one system thread can manage thousands of engines. Each

Process = one Runtime + Context + mailbox. Never shares JS state.

Scheduler = M worker threads pulling processes off a shared run queue.

Every file on the command line starts as its own process (pids 0..n ); the

runtime exits when all processes (including spawned ones) have finished.

otter can expose a JSON-RPC 2.0 control socket over TCP, letting an external

kill , send , rename , count , and shutdown . Enable it with

Serialize value to JSON and deliver it to pid 's mailbox. Messages to dead pids are dropped silently.

Suspend until a message arrives; resolves with the parsed value. With a timeoutMs it rejects with a TimeoutError if no message arrives in time (a message that races the deadline stays in the mailbox).

Suspend the process for at least ms milliseconds; does not touch the mailbox.

Voluntarily give up the current slice and rejoin the back of the run queue. (Not named yield because that word is reserved inside async-function bodies, which is how top-level-await scripts are parsed.)

Request termination of a live process; returns true if pid is live. Best-effort: the process is reaped at its next scheduling boundary (parked/sleeping processes immediately). Killing an unknown pid returns false .

Rename the current process; visible in listProcesses() / processInfo() .

## Related tools

- [Claude](https://linkrena.com/tools/claude): Claude is a next generation AI assistant built by Anthropic and trained to be safe, accurate, and secure to help you do your best work.
- [Your Mail Mcp](https://linkrena.com/tools/your-mail-mcp): Self-hosted, read-only MCP server that serves IMAP mail from a local notmuch index over authenticated HTTP - wildsurfer/your-mail-mcp
- [What is dmx?](https://linkrena.com/tools/what-is-dmx): dmx is an open source AI-native engineering harness.
- [Saccade](https://linkrena.com/tools/saccade): Closed-loop browser control runtime for AI agents.
- [Bridle](https://linkrena.com/tools/bridle): Bridle is an open protocol that connects your coding agent to your teammate's.
- [Proqi](https://linkrena.com/tools/proqi): A terminal-native prompt composer for power users running multiple coding agents.