Quickstart

Create a project, store a provider key, set a ceiling, and create a Fuse key. Put these two lines in the app.

FUSE_BASE_URL=https://fuse.ospalabs.com/v1
FUSE_API_KEY=fz_your_fuse_key

Pass them into the client. The same pair works whether the model is OpenAI, Anthropic, Google, Mistral, xAI, or a gateway you added.

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: process.env.FUSE_BASE_URL,
  apiKey: process.env.FUSE_API_KEY,
});

const res = await client.chat.completions.create({
  model: "gpt-4.1-mini",
  messages: [{ role: "user", content: "hi" }],
});

Order in the dashboard:

1. Create a project and name it after the app, not after the vendor.
2. Open the provider you will call and save its API key. Models stay locked until that key exists.
3. Turn on only the models that app should be able to use.
4. Set a daily ceiling, a monthly ceiling, or both, and the timezone the period should reset in.
5. Create a Fuse key and copy FUSE_BASE_URL and FUSE_API_KEY into the app.

A project with no plan can be configured, but the proxy answers 402 subscription_inactive until a subscription is active. A project with no ceiling answers 403 no_ceiling_configured.