killi

killi is a fast, tiny, free and open-source AI coding agent for your terminal, written in Rust. It ships as one ~7 MB native binary for Apple silicon Macs and Linux (x64 and arm64) — no runtime to install, starts in under 10 ms, and uses about 18 MB of memory while running a prompt. Like Claude Code, Codex CLI, opencode or Kimi Code, it reads your code, runs commands and edits files, but it works with any OpenAI-compatible, Anthropic-compatible or OpenAI Responses LLM, including ChatGPT subscriptions, and it supports MCP servers, subagents, plan mode, skills, hooks and AGENTS.md. It is built around one idea: send the model as little as possible, and send it the same way every time, so the provider's prompt cache keeps hitting (70–90% of input tokens come from the cache). It is the sibling of the Kil terminal and the Kiled editor.

killi at a glance

How these were measured: Size and memory · Capability tests.

Status: early but actively developed. macOS (arm64) and Linux (x64/arm64). Used daily by its author; see Known limitations.

Why killi

• Long sessions stay cheap. The prompt and tool list never change mid-session, and history is only appended to, so 70–90% of input tokens come from the provider's prompt cache.
• The same work, far fewer tokens. About 2,600 tokens for the whole prompt and every tool; every capability task Kimi Code passes, with 5.6× fewer input tokens.
• Almost invisible on your machine. One ~7 MB binary with no runtime to install, starting in under 10 ms and using about 18 MB of memory running a prompt.
• No model lock-in. Any OpenAI-compatible, Anthropic-compatible or OpenAI Responses LLM, on an API key or a ChatGPT subscription.
• The full agent kit. Subagents and swarms, plan mode, MCP servers, skills, hooks, AGENTS.md and undo — free and open source under MIT.

Install

curl -fsSL https://raw.githubusercontent.com/timwuhaotian/killi/main/install.sh | sh

This puts killi in ~/.local/bin after checking its SHA-256 against releases/latest.toml. Later, killi update does the same in place. It installs releases/killi-arm64 on macOS, releases/killi-linux-x64 or releases/killi-linux-arm64 on Linux. On Linux, four optional tools complete the picture: wl-copy/wl-paste (Wayland) or xclip/xsel (X11) for clipboard copy and image paste, notify-send for desktop notifications, ImageMagick (convert/magick) or ffmpeg for shrinking large images before they are sent, and a Chrome-family browser on PATH for pages that need JavaScript. Without them killi still works: copying falls back to the terminal's OSC 52, notifications to OSC 9 terminals, and large images are sent as-is.

Build from source

cargo install --path crates/killi

Rust 1.94 or later, on macOS (arm64) or Linux (x64/arm64).

Features

• Small and quick. One 7 MB binary with no runtime to install. It starts in under 10 ms and uses about 18 MB of memory running a prompt, where Kimi Code uses 408 MB, Claude Code 318 MB and opencode 2 332 MB.
• Few tokens. The system prompt and every tool together come to about 2,600 tokens, plus your AGENTS.md files and about 4 tokens per installed skill. In the capability tests killi passed every task Kimi Code passed, on the same model, with 5.6× fewer input tokens.
• Cache-friendly by design. The system prompt and the tool list are fixed for the whole session, and history is only appended to, never rewritten. Even plan mode, subagents and resumed sessions reuse the same cached prefix; 70–90% of input tokens come from the cache.
• An interactive mode that stays out of the way. The conversation prints into your terminal's own scrollback; only a small area at the bottom redraws: what's running, your task list, the prompt and a status line. Type / for a menu of commands and skills that narrows as you type. Type while the agent works and your message reaches it at its next step. Esc interrupts, and nothing it started keeps running.
• Plan mode (Shift+Tab): the agent researches and writes a plan; edits are blocked and bash runs only read-only commands until you approve it.
• Tools that forgive small mistakes. edit takes several changes in one call and still matches when only trailing spaces, smart quotes or dashes differ. Long output keeps its useful end and saves the rest to a file. Slightly broken tool-call JSON is repaired, not dropped.
• Subagents run in parallel on the same model and cached prompt. Swarms run one subagent per item of a prompt template, up to 128, several at a time, shown as one live panel (how many, which are working on what, how long each has run); swarm mode, on by default and set with [agent] swarm or /swarm, tells the agent to split its work that way. Background tasks keep servers and slow builds running. Undo puts your files back as they were before a turn, including what commands changed.
• Sessions that know about each other. Run several killi at once and each knows where the others work and what they are doing. killi card <pid> says what a session can be asked to do, as text or JSON; killi send <pid> <task> hands one a task, which it runs on an agent of its own and answers with a report (--async only takes its id back), killi tasks and killi task <id> [--follow] show where the tasks stand, and killi cancel <id> stops one. The agent is told when another session works in its repository, to leave that session's changes alone, and how to ask it about its work or leave it a message. Nothing is added to the system prompt or the tool list.
• Your setup, carried over. Kimi Code's config layout (killi import copies another agent's), skills from ~/.agents/skills, MCP servers from mcp.json, Claude Code-style hooks, and AGENTS.md (or CLAUDE.md) files, including ones in subfolders.
• Every session on disk, exactly as sent, so killi -c continues where you left off with the cache still warm.
• Updates itself. killi update installs the latest release after checking its checksum, and a session that finds a newer release (at start and every six hours) prints what changed since your version and asks whether to install it now. KILLI_NO_UPDATE_CHECK=1 turns the check off.

FAQ

What is killi? killi is a fast, tiny, open-source AI coding agent for the terminal, written in Rust. It ships as one ~7 MB native binary for Apple silicon Macs and Linux (x64 and arm64) with no runtime to install, starts in under 10 ms, and uses about 18 MB of memory while running a prompt. Like Claude Code, Codex CLI, opencode or Kimi Code, it reads your code, runs commands and edits files, but it is free (MIT), works with any OpenAI-compatible, Anthropic-compatible or OpenAI Responses LLM, and is built so the provider's prompt cache keeps hitting.

Is killi open source? Yes. killi is open source under the MIT license, and the full source is on GitHub at github.com/timwuhaotian/killi. It is free to use and installs as a single ~7 MB binary.

How is killi different from Claude Code? Claude Code is Anthropic's closed-source agent tied to Anthropic models. killi is open source, model-agnostic, and much lighter: in the same benchmark, killi used about 18 MB of memory while Claude Code used 318 MB, Kimi Code 408 MB and opencode 2 332 MB. In killi's capability tests, killi passed every task Kimi Code passed on the same model with 5.6× fewer input tokens. Because killi never changes the system prompt or the tool list during a session, 70–90% of its input tokens are served from the provider's prompt cache.

How much memory does killi use? About 18 MB of peak memory while running a prompt, measured on 2026-11-07 on an M4 Pro with scripts/bench.py (hooks disabled). For comparison, the same benchmark measured Kimi Code at 408 MB, Claude Code at 318 MB and opencode 2 at 33