0-->3 years developers are counted as junior developers.
You may ask a few questions or examine how they programme to distinguish good developers from this crowd of junior developers.

Back-end:
Ask junior developer to create a CRUD form with name, email and phone number.
Language: Any
Framework :Not allowed.

Once he create now check:
1- Did he used client side validation?
2- Did he also added server-side validation of form fields?
3- Did he used CSRF token ?
4- Did he expired CSRF token with session or before session or he is not expiring?
5- Did he used function and classes in crud?
6-Bot check with captcha before submission of form?
7- Did he made an approach with oop ?
8) Is the all values tabulated by developer is looped at once from database or every pagination is requesting fresh values.

Front-end:-
1) Ask to write media query for some standard devices.
2) Ask him to use calc to calculate padding value of div by device width.
3) Create a modal + multiple modal in a page.
4) create collapsable navbar.
5) Write manifest for pwa.
6) Write Service worker for pwa.
7) Do he know tools like lighthouse or gtmatrix?
8) Does he used meta tags?
9) Code quality as per seo.

Devops
1) Does he knows anything about load balancing? ( Hint him with HAPROXY)
2)Ask him to create a container with different resources.
3) Ask him to use iptables to listen a container / vm on any port.
4) Ask him about reserved ports like 80, 22,110 etc. Ask him is it possible to listen these ports of vm / container on any other port of host?
5) Ask him to write a shell script to download some softwares with shell scripts.
6) What are different popular Desktop Environments in linux.
7) Convert a server into desktop.
8) How to take server backup on any other remote drive / server.
9) What OCI means in container technology.
10) Update GitHub and server files get updated by itself. Does he know how to achieve it?

Let me know your views.