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

| | KrillClaw | Typical Edge Runtime | Desktop Agent | |---|:---:|:---:|:---:| | Binary | ~450 KB | 2–8 MB | 50–500 MB | | RAM | ~2 MB | 10–512 MB | 150 MB – 1 GB | | Source | 4,576 LOC | 5–30K LOC | 30–100K+ LOC | | Dependencies | 0 | 10–100+ | 100–1000+ | | Boot time | <10 ms | <1s | 2–5s | | Embedded/BLE | Yes | Sometimes | No | | Cron/Daemon | Yes | Sometimes | No |

vs Embedded/Edge Runtimes

| Feature | KrillClaw | MimiClaw | PicoClaw | |---------|:---------:|:--------:|:--------:| | Language | Zig | Python | Go | | Binary size | ~450 KB | ~2 MB | ~8 MB | | RAM usage | ~2 MB | ~512 KB* | ~10 MB | | Dependencies | 0 | pip | Go modules | | BLE transport | ✅ | ❌ | ❌ | | Serial transport | ✅ | ❌ | ❌ | | Multi-provider | 20+ (Claude, OpenAI, Ollama + 17 via --base-url) | 2 | 1 | | SSE streaming | ✅ | ❌ | ❌ | | Inline tests | 60 | 0 | Limited | | Sandbox mode | ✅ | ❌ | ❌ | | MCP support | ✅ | ❌ | ❌ | | Channels | 7 (Telegram, Discord, Slack, WhatsApp, MQTT, WebSocket, Webhook) | 2 | N/A | | GPIO / hardware | ✅ (GPIO, I2C, SPI) | ✅ (GPIO) | ❌ | | License | BSL 1.1 | MIT | MIT |

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

| File | Lines | Role | |------|------:|------| | main.zig | 198 | CLI, REPL, cron daemon entry point | | agent.zig | 215 | Agent loop + FNV-1a stuck-loop detection | | api.zig | 341 | Multi-provider HTTP client (Claude/OpenAI/Ollama) | | stream.zig | 362 | SSE streaming parser | | json.zig | 519 | Hand-rolled JSON parser/builder — zero deps | | tools.zig | 191 | Tool dispatcher — comptime profile + shared tools | | tools_shared.zig | 362 | Shared tools: time, KV, web search, sessions, OTA (all profiles) | | tools_coding.zig | 484 | Coding profile: bash, read/write/edit, search, list, patch | | tools_iot.zig | 176 | IoT profile: MQTT, HTTP, device info | | tools_robotics.zig | 153 | Robotics profile: commands, e-stop, telemetry | | context.zig | 226 | Token estimation + priority-based truncation | | config.zig | 202 | Config: file → env → CLI precedence | | cron.zig | 206 | Cron/heartbeat scheduler for daemon mode | | transport.zig | 179 | Abstract vtable transport + RPC protocol | | types.zig | 157 | Core types: Provider, Message, Config, ToolDef | | ble.zig | 159 | BLE GATT transport (protocol + simulation) | | serial.zig | 142 | UART/serial transport (Linux/macOS) | | arena.zig | 200 | Fixed arena allocator for embedded targets | | react.zig | 104 | ReAct reasoning loop |

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

| Profile | Tools | Binary Size | Security Policy | |---------|-------|:-----------:|-----------------| | coding | bash, read/write/edit, search, list, patch + shared | ~459 KB | bash behind approval gate, writes restricted to cwd | | iot | MQTT pub/sub, HTTP, GPIO, I2C, SPI, device info + shared | ~463 KB | no bash, no file writes, 30 req/min rate limit | | robotics | robot_cmd, estop, telemetry + shared | ~473 KB | no bash, bounds checking, 10 cmd/s, e-stop |

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.

| Provider | Models | Auth | |----------|--------|------| | Claude | claude-sonnet-4-5, claude-opus-4, etc. | ANTHROPIC_API_KEY | | OpenAI | gpt-4o, gpt-4-turbo, etc. | OPENAI_API_KEY | | Ollama | llama3, codellama, mistral, etc. | None (local) | | + 17 more | via --base-url | Provider-specific |

# 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