- Backend Dev – What a Backend Engineer Actually Does
The job, described by what lands in your queue rather than by a job posting. What you own — the API contract, the data, correctness under concurrency, and what happens at 3am — where the line sits between you and frontend, devops, DBA and data engineering, and what a real ticket looks like from request to deploy.
- Merge Sort
Split in half, sort each half, merge. O(n log n) in every case and stable, at the cost of O(n) extra space. Why stability is decided by a single <= in the merge, why the buffer should be allocated once, and why Java sorts objects this way.
- React – Routing with React Router
React has no router, so everyone uses this one. BrowserRouter, Routes and Route, Link instead of an anchor tag, URL params and query strings, programmatic navigation with useNavigate, layout routes with Outlet, and a guarded route that bounces signed-out users to the login page and back again.
- Spring Boot – OAuth2
The authorization code flow in the terms Spring actually names things, sign in with Google against the pizza app, and the piece every tutorial skips: reconciling an OAuth2 identity with the user row you already have, so the same person logging in both ways does not end up as two accounts.
- Angular – Reactive Forms and Validation
Forms defined in the class, where they can be typed and tested. `FormControl`, `FormGroup` and `FormArray`, typed forms and why `nonNullable` matters, sync and async validators, cross-field validation, and mapping the server's field errors back onto the right controls after a failed submit.