# How to Set Up Automattic/harper Locally: A Complete Development Guide > Set up Automattic/harper locally with our complete guide. Install Rust Node.js and pnpm, clone the repo, and run just setup for a seamless development environment. - Repository: [Automattic/harper](https://github.com/Automattic/harper) - Tags: how-to-guide - Published: 2026-07-26 --- **To set up Automattic/harper locally, install Rust (1.78+), Node.js (18+), pnpm (10.10.0), and wasm-pack, clone the repository, and run `just setup` to bootstrap the workspace with all Rust crates and JavaScript packages.** Harper is a multi-language grammar-checking platform built around a Rust core (`harper-core`) that compiles to native binaries, a WebAssembly module (`harper-wasm`), a JavaScript wrapper ([`harper.js`](https://github.com/Automattic/harper/blob/main/harper.js)), a language-server implementation (`harper-ls`), and a desktop Tauri app (`harper-desktop`). When you set up Automattic/harper locally, you gain the ability to modify the core engine, WebAssembly bindings, JavaScript API, editor extensions, and the desktop overlay. ## Prerequisites Before cloning the repository, ensure your system has the following tools installed. These versions are enforced by configuration files in the repository root. - **Rust** (stable 1.78+): Compiles the core engine and desktop native code. The exact version is pinned in [`rust-toolchain.toml`](https://github.com/Automattic/harper/blob/main/rust-toolchain.toml) in the repository root. - **Node.js** (18+): Required for JavaScript and TypeScript packages. The repository includes an `.nvmrc` file for version management. - **pnpm** (10.10.0): The monorepo uses pnpm workspaces to resolve inter-package links. This version is pinned in [`harper-desktop/package.json`](https://github.com/Automattic/harper/blob/main/harper-desktop/package.json). - **wasm-pack**: Builds the WebAssembly binary that [`harper.js`](https://github.com/Automattic/harper/blob/main/harper.js) loads in the browser. - **Tauri CLI** (2.x): Needed to run the desktop application during development. Install via `cargo install tauri-cli`. On macOS, you may need Xcode command-line tools. On Linux, install `build-essential`, `libssl-dev`, and `pkg-config` alongside `wasm-pack`. ## Clone the Repository Start by cloning the source code and changing into the directory: ```bash git clone https://github.com/Automattic/harper.git cd harper ``` The root [`README.md`](https://github.com/Automattic/harper/blob/main/README.md) contains the official clone instructions and links to further documentation. ## Install Toolchains ### Rust Install and activate the stable Rust toolchain specified in the repository: ```bash rustup toolchain install stable rustup default stable ``` The [`rust-toolchain.toml`](https://github.com/Automattic/harper/blob/main/rust-toolchain.toml) file at the repository root defines the required version, ensuring consistency across development environments. ### Node.js and pnpm If you use **nvm**, install the correct Node.js version from the `.nvmrc` file: ```bash nvm install nvm use ``` Then install the exact version of pnpm required by the workspace: ```bash npm install -g pnpm@10.10.0 ``` This version is enforced because [`pnpm-workspace.yaml`](https://github.com/Automattic/harper/blob/main/pnpm-workspace.yaml) relies on specific workspace protocol features to link [`harper.js`](https://github.com/Automattic/harper/blob/main/harper.js) and the web UI packages. ## Bootstrap the Workspace The project uses the **just** task runner to orchestrate complex build steps. The `justfile` in the repository root defines the `setup` task, which installs all workspace dependencies and compiles the Rust crates. Run the bootstrap command: ```bash just setup ``` This executes `pnpm install`, `cargo fetch`, and `wasm-pack build` in sequence, ensuring the `harper-wasm` package is available for the JavaScript applications. ## Build Core Components ### Compile the Rust Core Build the core library and command-line interface: ```bash just build-core ``` This command compiles `harper-core` and related crates as defined in the root [`Cargo.toml`](https://github.com/Automattic/harper/blob/main/Cargo.toml) workspace manifest. ### Build WebAssembly Generate the WebAssembly module for browser and Node.js usage: ```bash just build-wasm ``` This runs `wasm-pack` and outputs the compiled `.wasm` bundle to `harper-wasm/pkg`, which [`harper.js`](https://github.com/Automattic/harper/blob/main/harper.js) imports. The [`pnpm-workspace.yaml`](https://github.com/Automattic/harper/blob/main/pnpm-workspace.yaml) file includes this path to make the package available to dependents. ## Run Development Servers ### Web UI Start the Vite development server for the web interface: ```bash just dev-web ``` The server launches on `http://localhost:1420` as configured in [`packages/web/vite.config.ts`](https://github.com/Automattic/harper/blob/main/packages/web/vite.config.ts). This port is also proxied by the Tauri development server when running the desktop app. ### Desktop Application Launch the Tauri desktop application with live reloading: ```bash just dev-desktop ``` This builds the shared packages, compiles the Rust backend in `harper-desktop/src-tauri/`, and opens the overlay application. See [`harper-desktop/README.md`](https://github.com/Automattic/harper/blob/main/harper-desktop/README.md) for architecture details regarding the highlighter service. ### Language Server Start the language server for editor integration: ```bash just dev-ls ``` This runs the binary defined in [`harper-ls/Cargo.toml`](https://github.com/Automattic/harper/blob/main/harper-ls/Cargo.toml), enabling grammar checking in VS Code, Neovim, and other LSP-compatible editors. ## Verify Your Setup Run the complete test suite to ensure all components function correctly: ```bash just test-all ``` This executes Rust unit tests for `harper-core`, WASM binding tests, JavaScript/TypeScript tests for [`harper.js`](https://github.com/Automattic/harper/blob/main/harper.js), and integration tests across the workspace. The testing strategy is outlined in [`ARCHITECTURE.md`](https://github.com/Automattic/harper/blob/main/ARCHITECTURE.md). ## Summary - Install **Rust 1.78+**, **Node.js 18+**, **pnpm 10.10.0**, and **wasm-pack** before cloning the repository. - Run `just setup` from the repository root to install dependencies and build Rust crates according to the `justfile` definitions. - Use `just dev-web` to start the web UI development server at `http://localhost:1420` (configured in [`packages/web/vite.config.ts`](https://github.com/Automattic/harper/blob/main/packages/web/vite.config.ts)). - Use `just dev-desktop` to launch the Tauri application with the highlighter service. - Execute `just test-all` to validate the entire workspace against the test suite defined in [`ARCHITECTURE.md`](https://github.com/Automattic/harper/blob/main/ARCHITECTURE.md). ## Frequently Asked Questions ### What version of Rust do I need to build Harper? You need Rust 1.78 or later. The repository pins the exact version in [`rust-toolchain.toml`](https://github.com/Automattic/harper/blob/main/rust-toolchain.toml) at the root. Running `rustup default stable` ensures your toolchain meets this requirement before compiling `harper-core` or `harper-ls`. ### Why does the setup require pnpm instead of npm? The monorepo uses **pnpm workspaces** to manage inter-package links between [`harper.js`](https://github.com/Automattic/harper/blob/main/harper.js), the web UI, and the VS Code extension. The exact version (10.10.0) is pinned in [`harper-desktop/package.json`](https://github.com/Automattic/harper/blob/main/harper-desktop/package.json) to ensure consistent dependency resolution hoisting across the JavaScript packages. ### How do I lint text using the local command-line interface? After building the core, run `cargo run --bin harper-cli -- lint "Your text"` from the repository root. This executes the binary defined in [`harper-core/Cargo.toml`](https://github.com/Automattic/harper/blob/main/harper-core/Cargo.toml) without installing Harper system-wide, allowing you to test core grammar rules directly. ### Can I develop the language server without running the desktop app? Yes. Run `just dev-ls` to start the language server independently. This connects to supported editors like VS Code or Neovim via LSP, and the implementation is defined in [`harper-ls/Cargo.toml`](https://github.com/Automattic/harper/blob/main/harper-ls/Cargo.toml) without requiring the Tauri runtime.