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Run your app in dev mode. By default, this starts a multiplexer with processes that deploy your app, run your functions, and start your frontend. 
sst dev
The tabbed terminal UI is only available on Linux/macOS and WSL.

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How it works

Each process is run in a separate tab that you can click on in the sidebar. sst dev multiplexer mode The multiplexer makes it so that you won’t have to start your frontend or your container applications separately. Here’s what happens when you run sst dev:
  • Deploy most of your resources as-is.
  • Except for components that have a dev prop:
    • Function components are run Live in the Functions tab.
    • Task components have their stub versions deployed that proxy the task and run their dev.command in the Tasks tab.
    • Frontends like Nextjs, Remix, Astro, StaticSite, etc. have their dev servers started in a separate tab and are not deployed.
    • Service components are not deployed, and instead their dev.command is started in a separate tab.
    • Postgres, Aurora, and Redis link to a local database if the dev prop is set.
  • Start an sst tunnel session in a new tab if your app has a Vpc with bastion enabled.
  • Load any linked resources in the environment.
  • Start a watcher for your sst.config.ts and redeploy any changes.
The Service component and the frontends like Nextjs or StaticSite are not deployed by sst dev.

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Modes

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Multiplexer mode (default)

By default, sst dev runs in multiplexer mode with a tabbed terminal UI. This is the recommended mode for development. 
sst dev

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Mono mode

Disable the tabbed terminal UI by running sst dev in mono mode. 
sst dev --mode=mono
Unlike basic mode, this’ll spawn child processes. But instead of a tabbed UI it’ll show their outputs in a single stream. This is used by default in Windows.

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Basic mode

You can disable the multiplexer and not spawn any child processes by running sst dev in basic mode. 
sst dev --mode=basic
This will only deploy your app and run your functions. If you are coming from SST v2, this is how sst dev used to work. However in basic mode, you’ll need to start your frontend separately by running sst dev in a separate terminal session by passing in the command. For example: 
sst dev next dev
By wrapping your command, it’ll load your linked resources in the environment.

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Running commands

You can wrap commands with sst dev to run them with your linked resources loaded. 
sst dev next dev
To pass in a flag to the command, use --: 
sst dev -- next dev --turbo

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Options

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--mode

Defaults to using multi mode. Use mono to get a single stream of all child process logs or basic to not spawn any child processes. 
sst dev --mode=mono

sst dev --mode=basic

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--policy

Run policy pack validation against the preview changes. 
sst dev --policy ./policies/dev

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Arguments

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command

The command to run with linked resources loaded. 
sst dev next dev

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Examples

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Start your entire app

Brings up your entire app - should be all you need: 
sst dev

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Run a command with resources

Start a command connected to a running sst dev session: 
sst dev next dev

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Pass flags to the command

Use -- to pass flags to the command: 
sst dev -- next dev --turbo

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