.env.development ((full))

Rename your variable. DB_HOST becomes REACT_APP_DB_HOST .

New developers joining a team should clone the repo and run npm start without fighting database connections. A well-tuned .env.development provides sane defaults (e.g., a local SQLite database vs. a cloud PostgreSQL instance). .env.development

What it does

: Even though it's "for development," you must never include real secrets (like production database passwords or private API keys) in this file if it is committed to GitHub. Rename your variable

Many developers forget that frontend frameworks (React, Vue) bake environment variables at build time. If you run npm run build with NODE_ENV=development , your production bundle will contain dev API URLs. Always ensure your build pipeline uses .env.production . .env.development