---
title: Build and deploy
description: How the Go-to-Wasm build pipeline works — workers-assets-gen, wasm_exec.js, and wrangler.
---

A workers-go project deploys a JavaScript entry point that loads a Go Wasm binary. The templates set this up for you; this page explains the pieces.

## The build pipeline

The template `package.json` build script does two things:

```json
"build": "go run github.com/syumai/workers-go/cmd/workers-assets-gen -mode=go && GOOS=js GOARCH=wasm go build -o ./build/app.wasm ."
```

1. **`workers-assets-gen`** populates the `build/` directory with the runtime assets:
   - `wasm_exec.js` — the Go (or TinyGo) Wasm support file (`-mode=go` or `-mode=tinygo`).
   - `runtime.mjs` — the workers-go runtime for the target platform (`-runtime=cloudflare`).
   - Common assets such as the `worker.mjs` entry point.
2. **`go build`** compiles your code with `GOOS=js GOARCH=wasm` into `build/app.wasm`.

`wrangler.toml` points `main` at `./build/worker.mjs` and runs the build automatically:

```toml
main = "./build/worker.mjs"

[build]
command = "npm run build"
```

## workers-assets-gen flags

| Flag | Values | Default |
| --- | --- | --- |
| `-mode` | `go`, `tinygo` | `tinygo` |
| `-runtime` | `cloudflare` | `cloudflare` |
| `-o` | output directory | `build` |
| [`-durable-objects`](/cloudflare/durable-objects) | comma-separated Durable Object class names (e.g. `Counter,Room`) | (none) |
| [`-workflows`](/cloudflare/workflows) | comma-separated Workflow class names (e.g. `MyWorkflow,Other`) | (none) |
| [`-entrypoints`](/cloudflare/rpc) | semicolon-separated `Name` or `Name:method1,method2` RPC entrypoint specs (e.g. `MyService:add,greet;Other`) | (none) |

Each of these flags appends one subclass definition to the generated `worker.mjs` per name/spec — see the linked page for the wiring details (matching `wrangler.toml` binding, and the `Register` call on the Go side).

## Go vs TinyGo

The `worker-go` template uses the standard Go toolchain (Go 1.24+). The `worker-tinygo` template uses TinyGo 0.42.0 or later, which produces a much smaller Wasm binary — worth it for faster cold starts. TinyGo 0.41.x cannot build `net/http` for Wasm.

A [`durable-object-go`](https://github.com/syumai/workers-go/tree/main/_templates/cloudflare/durable-object-go) template is also available, preconfigured with the `-durable-objects` flag and a `wrangler.toml` binding/migration:

```sh
npm create cloudflare@latest -- --template github.com/syumai/workers-go/_templates/cloudflare/durable-object-go
```

## Deploy

```bash
npm run deploy   # wrangler deploy
```

Wrangler runs the build command, uploads the Wasm binary and the JS entry point, and publishes the worker.