KrillClaw

~450KB binary. 0 dependencies. 19 source files. 50+ validated device targets. Runs on a $3 microcontroller or a cloud server.

KrillClaw is an autonomous AI agent runtime written in Zig. It connects to 20+ LLM providers (Claude, OpenAI, Ollama + 17 via --base-url), executes tools, and loops until the task is done. Includes cron scheduling, persistent KV store, MCP support, 7 messaging channels, GPIO/hardware control, and BLE/Serial transports for edge devices.

 ┌──────────────────────────────────────────────────────┐
 │                                                      │
 │   ~450 KB.  Zero deps.  Boots in <10ms.              │
 │   The entire agent runtime — LLM client, tool        │
 │   executor, JSON parser, SSE streaming, cron,        │
 │   KV store, context mgmt — in 4,576 lines of Zig.   │
 │                                                      │
 └──────────────────────────────────────────────────────┘

Quick Start

# 1. Install Zig 0.15+ → https://ziglang.org/download/
# 2. Clone and build (takes ~1 second)
git clone https://github.com/krillclaw/KrillClaw.git
cd KrillClaw
zig build -Doptimize=ReleaseSmall

# 3. Set your API key and go
export ANTHROPIC_API_KEY=sk-ant-...
./zig-out/bin/krillclaw "create a REST API in Go with user auth"

That's it. No npm install. No pip. No Docker. Just Zig and a binary.

Why KrillClaw?

Every AI agent runtime is massive. Desktop coding agents ship as 50–500MB bundles with hundreds of dependencies. The actual logic — "call LLM, parse response, execute tools, repeat" — shouldn't need any of that.

KrillClaw proves it doesn't. The same agentic loop that powers desktop tools, compiled to a binary smaller than a JPEG, running on hardware that costs less than a coffee.

KrillClaw exists because AI agents should run everywhere — not just on machines with Node.js and 8GB of RAM.

The Numbers

vs Embedded/Edge Runtimes

Competitor data as of Feb 2026. Check their repos for current numbers.

Architecture

┌─────────────────────────────────────────────────────────────┐
│                        KrillClaw                             │
│                                                              │
│  ┌─────────┐    ┌──────────┐    ┌────────────┐              │
│  │  main    │───▶│  agent   │───▶│  tools     │              │
│  │  (CLI)   │    │  (loop)  │    │  (dispatch)│              │
│  └─────────┘    └────┬─────┘    └─────┬──────┘              │
│                      │                │                      │
│                 ┌────▼─────┐    ┌─────▼──────────────┐      │
│                 │   api    │    │  tools_coding.zig   │      │
│                 │ (client) │    │  tools_iot.zig      │      │
│                 └────┬─────┘    │  tools_robotics.zig │      │
│                      │          └────────────────────┘      │
│               ┌──────▼──────┐                                │
│               │  transport  │  ◀── vtable dispatch           │
│               └──┬────┬──┬──┘                                │
│                  │    │  │                                    │
│              ┌───▼┐ ┌▼──▼┐                                   │
│              │HTTP│ │BLE │ │Serial│                           │
│              └────┘ └────┘ └──────┘                           │
│                                                              │
│  Support: json.zig │ stream.zig │ context.zig │ config.zig  │
│           types.zig │ arena.zig                              │
└─────────────────────────────────────────────────────────────┘

19 files. 4,576 lines. Zero dependencies.

Source Map

Profiles

Compile-time profiles select different tool sets. Only the selected profile's code ships in the binary — zero runtime overhead.

# Coding agent (default)
zig build -Dprofile=coding -Doptimize=ReleaseSmall

# IoT agent — MQTT, HTTP, KV store, device info
zig build -Dprofile=iot -Doptimize=ReleaseSmall

# Robotics agent — motion commands, e-stop, telemetry
zig build -Dprofile=robotics -Doptimize=ReleaseSmall

All profiles include shared tools available across every profile:

• get_current_time — ISO-8601 timestamp
• kv_get / kv_set / kv_list / kv_delete — persistent key-value store

All profiles support sandbox mode: zig build -Dsandbox=true

Cron / Heartbeat (Daemon Mode)

Run KrillClaw as a scheduled agent on edge devices:

# Run agent every 5 minutes with a custom prompt
krillclaw --cron-interval 300 --cron-prompt "check sensors and report anomalies"

# Heartbeat every 60 seconds + agent every 10 minutes
krillclaw --heartbeat 60 --cron-interval 600

# Run 10 times then exit
krillclaw --cron-interval 120 --cron-max-runs 10 --cron-prompt "collect data"

Designed for edge devices running data collection cycles between connectivity windows (BLE, Serial). The scheduler has minimal binary cost (~2KB) and uses no threads.

Providers

KrillClaw supports 20+ LLM providers through three protocol backends. Any provider with an OpenAI-compatible API works via --base-url.

# Claude (default)
./zig-out/bin/krillclaw "fix the tests"

# OpenAI
export OPENAI_API_KEY=sk-...
./zig-out/bin/krillclaw --provider openai -m gpt-4o "fix the tests"

# Local Ollama
./zig-out/bin/krillclaw --provider ollama