Run frontend and backend together

The quickest way is one command that starts them all in one terminal, with each line labelled. With concurrently:

npx concurrently -n db,api,web \
  "docker compose up postgres" \
  "cd api && uv run fastapi dev" \
  "npm --prefix web run dev"

Or with a Procfile and a Procfile runner (foreman, overmind or honcho):

db: docker compose up postgres
api: cd api && uv run fastapi dev
web: npm --prefix web run dev
worker: cd api && uv run python -m worker

overmind start      # or: foreman start, honcho start

Which tool should I use to run several dev servers at once?

Each one is good at something:

• concurrently lives in package.json, so npm run dev starts everything for the whole team, in CI too. It runs them side by side in one terminal; it doesn’t wait for one to be ready before the next, so people add wait-on for the database.

• A Procfile runner reads a Procfile committed with the code, and works on any machine with a terminal, over SSH too. Overmind runs each process in tmux, so you can attach to one or restart it.

• tmux gives each process its own pane, a real terminal, in a session that survives closing the window:

  tmux new-session -d -s app 'cd api && uv run fastapi dev'
  tmux split-window -t app 'npm --prefix web run dev'
  tmux attach -t app

If one of these covers your day, keep it. They are free, small and scriptable.

Where do one-terminal setups fall short?

• Everything restarts together. Changing the API’s environment means stopping the frontend too, with most of them.
• “Started” isn’t “ready”. The API starts before Postgres accepts connections, fails once, and you restart it by hand.
• A failure scrolls away. Which one crashed, and why, is somewhere up in the shared output.
• It’s one more tab. Five projects means five of these, each in a tab you have to find again.

How does localhost run a whole project?

localhost is a free, open-source desktop app for exactly this. A Project is your folder; each Service is one of the commands above, run in your login shell, so your PATH and version managers apply. No Docker is required: a Compose service is just one more Service, such as docker compose up postgres.

• Start All, in order. Make the API start after the database. Start All (⇧⌘R, or Ctrl+Shift+R) starts every Service in dependency order, and each waits until its Dependencies are Running, which, for a Service with a Port, means the port accepts connections.
• One at a time when you want. Start, stop or restart a single Service (⌘R, ⌘.) and leave the rest running. A Service marked Manual stays out of Start All until you need it.
• One log, or each one. All services shows every Service’s output in one stream, each line prefixed with its Key. Select one to see only its log, kept per Run.
• Failures that say why. A Service that crashes is Failed, with the reason and its last lines, and the Services waiting for it don’t start, and say so.
• Every project in one window. Each Project keeps its Services, Ports and environment, so the next one is a click away, not another tab.

Set it up in a minute: localhost scans the folder and suggests Services from package.json scripts, Compose files, Python apps and Cargo binaries (Quick start). For where each tool wins, side by side: localhost compared to concurrently, to Procfile runners, to tmux and all comparisons.

FAQ

How do I make the backend wait for the database?

With concurrently, prefix the command with wait-on: npx wait-on tcp:5432 && uv run fastapi dev. In localhost, make the API start after the database: it waits until the database is Running, which for a Service with a Port means the port accepts connections.

Can I restart one service without stopping the others?

Not with concurrently, which runs them as one command. Overmind can restart one process (overmind restart web). In localhost, ⌘R restarts the selected Service and ⌘. stops it; the others, and the Services that depend on it, keep running.

Does localhost replace my Procfile or package.json scripts?

No. It runs them: a Service’s command can be npm run dev, overmind start or anything else your terminal runs. It writes nothing into your repository, so the team keeps its own setup.