Crab Code

Open-source alternative to Claude Code, built from scratch in Rust.

[](https://www.rust-lang.org/) [](LICENSE) [](https://github.com/lingcoder/crab-code/actions/workflows/ci.yml) [](#contributing)

English | [中文](README.zh-CN.md)

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> Active Development — 4970 tests · 26 crates · ~161k LOC

Crab Code is a Rust-native agentic coding CLI. It aligns with Claude Code's toolset, permission model, and interaction patterns while supporting any LLM provider (Anthropic / OpenAI / DeepSeek / Bedrock / Vertex).

Quick Start

git clone https://github.com/lingcoder/crab-code.git && cd crab-code
cargo build --release
export ANTHROPIC_API_KEY=sk-ant-...

./target/release/crab                   # Interactive TUI
./target/release/crab "explain this codebase"   # Single-shot
./target/release/crab -p "fix the bug"  # Non-interactive

See crab --help for more. Config lives at ~/.crab/config.toml (snake_case TOML); the full loading & merge spec is in [docs/config-design.md](docs/config-design.md).

Configuration

Config sources, low → high priority:

defaults       (file layer)
                                                            `**: CLI-injected file
- **`-c key.path=value`**: dotted runtime override (TOML grammar; repeatable)

Example `config.toml`:

```toml
api_provider = "deepseek"
base_url = "https://api.deepseek.com/v1"
model = "deepseek-chat"
api_key = "sk-..."           # optional; env wins if both set

[permissions]
allow = ["Bash(git:*)", "Read", "Edit"]
deny  = ["Bash(rm:*)"]       # deny always wins over allow

Environment Variables

Env (runtime layer) always wins over file. Mutually-exclusive variants apply highest-first.

| Category | Variable | Purpose | |----------|----------|---------| | Provider | CRAB_API_PROVIDER | Override provider: anthropic, openai, deepseek, bedrock, vertex, custom | | Provider | CRAB_API_KEY | Universal API key (any provider; highest priority) | | Provider | CRAB_MODEL | Override model name | | Provider | CRAB_BASE_URL | Universal base URL override | | Provider | CRAB_CONFIG_DIR | Relocate config root (default ~/.crab/) | | Provider | ANTHROPIC_API_KEY / ANTHROPIC_AUTH_TOKEN | Anthropic provider only | | Provider | ANTHROPIC_BASE_URL | Anthropic base URL (only when CRAB_API_PROVIDER=anthropic) | | Provider | OPENAI_API_KEY | OpenAI provider | | Provider | OPENAI_BASE_URL | OpenAI base URL (only when CRAB_API_PROVIDER=openai) | | Provider | DEEPSEEK_API_KEY | DeepSeek provider | | Provider | DEEPSEEK_BASE_URL | DeepSeek base URL (only when CRAB_API_PROVIDER=deepseek) | | Bedrock | AWS_ACCESS_KEY_ID / AWS_SECRET_ACCESS_KEY | Static credentials | | Bedrock | AWS_SESSION_TOKEN | Optional session token (temporary credentials) | | Bedrock | AWS_REGION / AWS_DEFAULT_REGION | AWS region | | Bedrock | AWS_ROLE_ARN | IAM role ARN to assume | | Bedrock | AWS_WEB_IDENTITY_TOKEN_FILE | OIDC token file (web-identity role assumption) | | Bedrock | AWS_EXTERNAL_ID | External ID for cross-account role assumption | | Bedrock | AWS_ROLE_SESSION_NAME | Session name for assumed role | | Vertex | GOOGLE_CLOUD_PROJECT / GCLOUD_PROJECT | GCP project ID | | Vertex | GOOGLE_CLOUD_REGION | GCP region (default: us-central1) | | Vertex | GOOGLE_APPLICATION_CREDENTIALS | Path to service account key JSON | | Shell | CRAB_SHELL | Path to bash/zsh binary (overrides auto-detection for the Bash tool) | | Shell | SHELL | POSIX fallback when CRAB_SHELL is unset | | Shell | CRAB_USE_POWERSHELL_TOOL | Truthy value exposes the PowerShell tool on Windows (default off) | | Agent | CRAB_COORDINATOR_MODE | 1 enables Agent Teams coordinator mode | | Agent | CRAB_AUTO_DREAM | 1 enables background memory consolidation between sessions | | Agent | CRAB_AUTO_DREAM_MIN_HOURS | Minimum hours between consolidations (default: 6) | | Agent | CRAB_AUTO_DREAM_MIN_SESSIONS | Minimum sessions before consolidation triggers (default: 2) | | TLS | CRAB_CA_BUNDLE | Path to custom CA certificate bundle (PEM) | | TLS | SSL_CERT_FILE / SSL_CERT_DIR | Standard OpenSSL CA overrides |

Comparison

| | Crab Code | Claude Code | OpenCode| Codex CLI | |--|-----------|-------------|---------|-----------| | Open Source | Apache 2.0 | Proprietary | MIT | Apache 2.0 | | Language | Rust | TypeScript | TypeScript | Rust | | Models | Any provider | Anthropic | Any provider | OpenAI only | | MCP | 3 transports | 6 transports | LSP | 2 transports |

Architecture

26 Rust crates in 4 layers. See [docs/architecture.md](docs/architecture.md) for details.

Entry     cli
Engine    agents · engine · session · tui · remote
Service   api · tools · commands · hooks · mcp · acp · skills · plugin · telemetry · ide · sandbox · swarm · cron · fs · memory · process
Foundation core · utils · config · auth

Build & Test

cargo build --workspace
cargo nextest run --workspace          # or: cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings

Contributing

PRs welcome.

License

[Apache License 2.0](LICENSE)

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: lingcoder
• Source: lingcoder/crab-code
• License: Apache-2.0
• Homepage: https://github.com/lingcoder/crab-code

Install and usage instructions live in the source repository linked above.