What skills does a full stack developer need?

Junior skills - both sides of one feature

On the frontend: semantic HTML, CSS layout with flexbox and grid, JavaScript, and React basics - components, props, useState, useEffect, forms and fetch. On the backend: an Express or FastAPI server with REST endpoints, correct status codes and input validation. Store data in PostgreSQL with simple SQL. Use browser dev tools to read the Network and Console tabs.

Mid-level skills - the parts between the two

Handle CORS, cookies and sessions, and JWT login. Upload files to cloud storage such as S3 with presigned URLs. Use TypeScript on both sides and validate data with a library like Zod. Manage loading and error states in the UI. Write tests for both sides and deploy the app with Docker.

Senior skills - design and scale

Choose how state moves between client and server, plan caching on both sides, and design APIs that other teams can use. Watch performance: bundle size, slow queries, and too many requests. Lead security choices like cookie flags, CSRF protection and safe file handling.

How to show these skills to an employer

A full stack portfolio should show that you can follow a problem from the browser to the database. Good examples: a React page that showed nothing until you found the broken fetch, a CORS error you traced to the server config, an avatar upload you built end to end. Write each one up in a few lines on one portfolio page.

Real Fullstack work to put in your portfolio

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