For me, no. On the surface it might make sense, but just no. I want someone who values their time, their skills and they know their value. Offering to work for

For me, no. On the surface it might make sense, but just no. I want someone who values their time, their skills and they know their value. Offering to work for free, for a for profit company, shows me you don't value your skills and assign worth to them. If you want to demonstrate your skills in a volunteer way, there are lots of open source projects that lack attention. Show me what you can do there, fix an outstanding issue or at least toss up a PR so I can see your work, if you're able to adhere to the projects guidelines etc... and you'll be contributing to something that benefits everyone. I despise lengthy coding interviews, and this idea of working for a day for nothing... Any company that would do that is a big red flag. If they have a minor task that can be completed in a day or two without full onboarding then they can pay for that limited amount of time as well. As much as a prospective employee should want to demonstrate their work ethic, and employer should want you demonstrate how it values the time and skills of their workers... They do that not with pats on the back or pizza parties, they do it with money.