[nassimsoftware]

How would you go about demonstrating that you're a dev that do things properly in your resume?

Considering the code I wrote for work is in private repos, would you have to create an open source project to demonstrate this to future employers?

[bern4444]

Put the projects on your resume along with the associated impact.

In interviews you'll be asked about them. If you're not mention them or refer to them in your answers to other questions! Discuss your approach to the design of those projects, considerations, performance tradeoffs, how you approached testing, how deployments were handled etc.

Mention the tools you used that made a big difference - maybe swapping compilers led to faster build times and smaller bundles. Swapping test runners led to improved test times. Maybe you tried to swap test runners and that increased test times and so you went back to the previous one. Maybe you led an effort to automate deployments!

Discussing migrations from old patterns to newer ones demonstrates that you know what good tools are available and you know how to leverage them.