Quickstart

From nothing to one App your code and agents can use through SDK, MCP, or REST. Roughly ten minutes, most of it waiting on a browser tab.

You need a Fused workspace. Choose Fused Cloud for a hosted Engine with a managed database, or self-host Fused in your own infrastructure. PostgreSQL setup is only required for self-hosting.

Install

curl -sSL https://raw.githubusercontent.com/Usefused/cli/main/install.sh | bash
fused-cli --version

For automated or non-interactive installs, set ASSUME_YES=1 to skip the confirmation prompt. Save your workspace’s HTTP URL. For Fused Cloud, use the URL from Open Fused Engine after signup. For self-hosting, use your Engine’s reachable HTTP address (http://localhost:8081 for a local deployment). Replace the example below with that address:

fused-cli config set engine-url https://your-workspace.run.usefused.com
fused-cli login

This opens your Fused deployment’s sign-in page and saves a subject-scoped credential after you approve it. The credential never passes through the browser and is never printed.

fused-cli whoami

On a headless machine, fused-cli login --no-browser prints the URL instead of trying to open one.

Choose your service’s authentication

For a supported OAuth integration, use a Managed service to connect users without registering your own provider app. Alternatively, store your own credentials. Managed auth is an explicit app configuration choice; init does not automatically choose it when local credentials are missing. Use --no-apply while preparing the managed reference, then plan and apply the completed config.

Create an App

fused-cli init support-app --service linear

Without a method flag, fused-cli init creates one App with SDK, MCP, and REST delivery. It searches your workspace and then the Registry, pins a concrete service version, and automatically selects all operations for a bare service such as linear. Use semicolons to select several services in one quoted value: --service 'linear;slack'. To select only specific operations, add = after each service and separate its operations with commas:

fused-cli init support-app \
  --service 'linear=issueUpdate;slack=chatPostMessage,conversationsList'

Choose either initialization command. Quote values containing semicolons so your shell passes them as one argument. The SDK guide covers version pins and mixed selections. If activation is needed, the CLI shows one combined confirmation. It writes separate workspace and App receipts. Missing provider credentials open a review menu: set them up in the terminal, open bucket setup in the browser, recheck readiness, proceed anyway, or cancel creation. Setup and recheck refresh the plan; you can repeat the review while credentials are still missing. Choose Proceed anyway to publish with readiness warnings. Cancelling stops before app publication. When the command succeeds, Fused applies one immutable App version, downloads its typed SDK package, and reports its hosted MCP URLs. REST execution uses that same version ID and token. Init writes one kind: sdk config with nested mcp delivery, plus a workspace config if service activation was needed. If no suitable Registry service exists, import the API yourself from a spec, a GraphQL endpoint, or the provider’s documentation.

The first successful initialization prints the App execution token once. Capture it now — a repeat apply will not show it again.

Automating this? Run fused-cli init support-app --service linear --no-input for all Linear operations, or use --service 'linear=issueUpdate' for only that operation. No method flag is needed for the combined App. Missing credentials are reported as readiness metadata without blocking publication. You may pre-provision them with connect with explicit values and --no-input, or let the first affected call return the exact safe setup command. For structured plan and apply output, use the advanced controlled workflow.

Call it

The SDK, MCP server, and REST endpoint use the same selected operations and execution token.

Way	Reach for it when	What it needs
`fused-cli app invoke`	Checking the path works, or trying an operation by hand	The CLI and the token
The typed package	Your application calls this for real	The downloaded package and Fused’s gRPC address
`POST /v1/apps/{id}/executions`	You use a language other than TypeScript, Python, or Go, or prefer calling over HTTP	Fused’s HTTP address and the version ID from apply
Hosted MCP	An agent discovers and executes selected operations	The stable MCP URL from apply or the App details page

export FUSED_APP_TOKEN='...'

fused-cli app invoke support-app@1.0.0 issueUpdate \
  --params '{"id":"ISS-42","state":"done"}'

import { FusedSDK } from 'support-app';

const sdk = new FusedSDK({
  grpcUrl: process.env.FUSED_ENGINE_GRPC_URL,
  token: process.env.FUSED_APP_TOKEN!,
});

const result = await sdk.Linear.issueUpdate({ id: 'ISS-42', state: 'done' });
if (result.ok) console.log(result.data);

curl -X POST "$FUSED_ENGINE_URL/v1/apps/$VERSION_ID/executions" \
  -H "Authorization: Bearer $FUSED_APP_TOKEN" \
  -H 'Content-Type: application/json' \
  -d '{"operation":"issueUpdate","input":{"id":"ISS-42","state":"done"}}'

A call returns { ok, status, data, error } rather than the payload itself, and services sit on the client in PascalCase with operations following the provider’s own grouping — so issueUpdate may be sdk.Linear.issues.update. Using it in your app covers the whole shape; your package’s generated README.md lists the exact paths for the operations you selected. Whichever one you used, the receipt is the same:

fused-cli app activity support-app@1.0.0

It shows what ran, how long the provider took, and what came back.

What you just did

workspace  →  approved a concrete service version when it was missing
bucket     →  supplied a credential your code will never see
app        →  published one immutable version for SDK, MCP, and REST delivery

Where to go next

Choose SDK-only delivery

Create a package without hosted MCP when you need one method.

Deploy an MCP server

Choose MCP-only delivery when you need a server without a package.

Connect user accounts

OAuth per end user, with refresh handled by Fused.

Share access

Give a team what it needs without giving it everything.

Prefer your coding agent to drive this?

The CLI ships skills that teach Claude Code, Codex, Cursor, Windsurf, and Antigravity the exact workflows above.

fused-cli skill list
fused-cli skill install --for claude

Taking this further

You have a working App on a Dev license. The tiers above it are about production licensing, SSO, and support — not about unlocking features you have just been using. When you need those, register interest and we’ll size it with you.

Get Started

Guides

Advanced

Reference

Install

Choose your service’s authentication

Create an App

Call it

What you just did

Where to go next

Choose SDK-only delivery

Deploy an MCP server

Connect user accounts

Share access

Prefer your coding agent to drive this?

Taking this further

​Install

​Sign in

​Choose your service’s authentication

​Create an App

​Call it

​What you just did

​Where to go next

Choose SDK-only delivery

Deploy an MCP server

Connect user accounts

Share access

​Prefer your coding agent to drive this?

​Taking this further

Install

Sign in

Choose your service’s authentication

Create an App

Call it

What you just did

Where to go next

Prefer your coding agent to drive this?

Taking this further