WASM Quickstart

Use Blazen in the browser or Node.js via WebAssembly

What is blazen-wasm-sdk?

The Blazen WebAssembly SDK is the core Rust library compiled to WASM. It runs the same completion, streaming, agent, and workflow logic as the native Rust crate — directly in the browser or in any JavaScript runtime that supports WebAssembly (Node.js, Deno, Bun, Cloudflare Workers).

The package is published as @blazen/sdk on npm.

Installation

npm install @blazen/sdk

Or with pnpm/yarn:

pnpm add @blazen/sdk
yarn add @blazen/sdk

Basic usage

Initialize the WASM module, then construct a provider directly and call complete() on it:

import init, { OpenRouterProvider, ChatMessage } from '@blazen/sdk';

await init();

// Construct the provider directly. With no apiKey, it reads OPENROUTER_API_KEY
// from the runtime environment.
const model = new OpenRouterProvider({ apiKey: 'sk-or-...' });
const response = await model.complete([ChatMessage.user('Hello!')]);
console.log(response.content);

init() loads and instantiates the WASM binary. Call it once before using any other export. In most bundlers (Vite, webpack 5, etc.) the binary is resolved automatically.

Streaming

Stream tokens as they arrive using model.stream():

import init, { OpenAiProvider, ChatMessage } from '@blazen/sdk';

await init();

// With no apiKey, the provider reads OPENAI_API_KEY from the environment.
const model = new OpenAiProvider({ apiKey: 'sk-...' });

await model.stream(
  [ChatMessage.user('Write a haiku about WebAssembly')],
  (chunk) => {
    if (chunk.delta) {
      document.getElementById('output').textContent += chunk.delta;
    }
  }
);

Each chunk has the shape { delta?: string, finishReason?: string, toolCalls: ToolCall[] }.

Completion options

Pass options like temperature and maxTokens through completeWithOptions():

const response = await model.completeWithOptions(
  [ChatMessage.user('Explain WASM in one sentence.')],
  { temperature: 0.3, maxTokens: 100 }
);

API key security

WASM runs client-side in the browser. Never embed raw API keys in frontend code shipped to users. Common strategies:

  • Proxy server — route requests through your own backend that injects the key.
  • Short-lived tokens — issue scoped, time-limited tokens from your server.
  • Server-side only — run the WASM SDK in Node.js / Deno / edge functions where keys stay secret.

Next steps