Webiny Docs home page
WHAT YOU'LL LEARN
  • how to develop the Admin UI locally with hot reload
  • how the Local Lambda Development system works for API changes
  • when and why you need to redeploy after stopping watch mode
  • how environment variables work in a Webiny project

Overview
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Webiny runs on AWS, but you develop locally. The watch commands connect to your deployed infrastructure and let you see changes instantly — without redeploying after every edit. This gives you a fast feedback loop for both frontend and backend work.

Before using the watch commands, make sure your project is deployed. If you followed the Quickstart, you already have a dev environment running.

Admin Development
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Start the Admin development server:

This launches a local React dev server at http://localhost:3001 with hot module replacement. Changes to Admin extensions — themes, branding, custom views, navigation items — appear instantly in the browser.

This is a standard React development experience. You can use browser DevTools, React Developer Tools, and all the debugging techniques you already know.

API Development
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Start the API development server:

This activates Local Lambda Development — a hybrid approach that runs your backend code locally while staying connected to real AWS services (DynamoDB, S3, Cognito, and others).

Here is how it works:

  • Your deployed Lambda functions are temporarily replaced with stubs that forward incoming events to your local machine
  • Your code executes locally with the full AWS Lambda context (environment variables, permissions, and everything else)
  • Responses are sent back through the Lambda stubs to the caller

The result: you see backend changes — GraphQL schemas, lifecycle hooks, content models, business logic — take effect immediately, without waiting for a deployment. Console logs appear directly in your terminal.

You must redeploy after stopping watch

When you stop yarn webiny watch api, your Lambda functions still contain the forwarding stubs — not your actual code. You must run yarn webiny deploy api to restore the real Lambda code and make your API functional in the cloud again.

The watch command prints a reminder when you stop it.

Running Both
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You can run both watch commands at the same time in separate terminals:

This gives you the full local development experience — backend and frontend changes reflected in real time.

Environment Variables
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Webiny projects do not require a .env file by default. Most configuration is handled through webiny.config.tsx and build parameters.

When you do need environment variables, use prefixes to target the right application:

  • WEBINY_ADMIN_ — only loaded in the Admin application
  • WEBINY_API_ — only loaded in the API application

Place them in a .env file at your project root. The prefixes prevent variables from leaking between applications.

Joining an Existing Project
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If you are joining a team that already has a Webiny project, the onboarding is straightforward:

No scaffolding commands, no special setup. Install dependencies and you are ready to start developing.

If the team uses environment variables, check for a .env.example file in the project root — it documents the required variables and their purpose. The actual .env file is typically excluded from version control, so you will need to create your own copy and fill in the values your team provides.

What's Next
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You now know the local development workflow. The final step is understanding how deployment works in more detail — environments, individual application deploys, and teardown.

Continue to Deploy Webiny.