The best devs I know dont have portfolio pieces. They tend to work on problems that the people employing them pay a lot of money to prevent being public.<p>So for me portfolios are for junior devs & graduate students looking to leave academia. Therefore, I look for things that are uncommon in those environments, engineering over theory, documentation & tests over novelty.<p>Note: if I were hiring for a researcher the above would not be true.
Look for "fit & finish" in a completed app. There is an old saying: "we're 90% done, now all we have to do is the remaining 90%!" I like to see that polish. It implies an understanding of the craft that is required, attention to detail, good debugging skills and an appreciation of human-centric design principles.
Anything at all relevant to the role - same language, same functionality at least.<p>Ideally things like good tests, good code structure, personally I'd also like to see a stable language choice too - if you're jumping from one language to the next to the next I'll probably assume you're going to want to rewrite everything in the new hotness every other week and that's a pain in the arse.<p>Associated blog posts that explain how your code works and why though? I'd put your name to the top of the "get this person in" list on the spot
Authentication.<p>i.e. Have you successfully implemented a good OAuth[2] security system? Can you explain the difference between JWTs, and session auth? Why choose one over the other. Talk to me about SSL a little bit, even at a high-level. How do you secure APIs? Talk to me about how you encrypt passwords, and sensative data.<p>Have you had to deal with PCI DSS?<p>This is one of the differences between "I'm a developer who has maintained a simple CRUD app" and "I'm a senior developer who can build a secure system".<p>Or in other words, authentication separates the men from the boys.
I like seeing personal projects that solve interesting problems, and that show that the person really considered the use cases and application of their project (UX design, functionality, etc.). There are good engineers, and then there are engineers that focus on why/who they are doing the engineer and I think that's really important, especially in a startup setting where people need to be intelligent self starters and hold themselves to high standards without having someone breathing down their neck.
I like to see lots of personal projects, the more complete and fleshed out the better, it shows you have a passion for the craft. I'm also slightly biased in favor of people without a college degree like myself, but I certainly wouldn't hold a degree against anyone.<p>so my most impressive candidate would be someone without a degree and quite a few very complete and well polished personal projects.
I like to see projects that people are obviously passionate about. A project that someone worked on with passion is likely to be some of their best work and best ideas melded together. If the output of that is good, they're probably worth giving a shot.
Something that has shipped, acquired customers and made money. Those things are more impressive to me than what framework, programming language, etc. you used.
Something with a vibrant community built up around it is most impressive to me. It shows a degree of communication and management, not to mention marketing.<p>Otherwise, most github repos are not that impressive as I have no idea how long it took to write (did it take a few months to write something most devs could write in a few days?), or if the candidate even wrote it at all.