I once had the impression that an indie hacker is a one person dev shop that sells a software product instead of their time.
But lately, I saw many people use that term for business people on the look for the next hustle.
Even if someone starts out as a "one person dev shop", they eventually become a business person, out of necessity.
Patrick McKenzie (patio11), who famously built and sold his "Bingo Card Creator", and blogged about the process, is a "prototypical" Indie Hacker.
The ecosystem consists of communities like [1] and [2], podcasts (search for "Indie Hackers"), and conferences like [3]
[0] https://training.kalzumeus.com/newsletters/archive/selling_s...
People define it differently, but generally I think of indie hackers as people, usually technical, who are building or are aiming to build smaller tech businesses. They generally either bootstrap or raise small amounts of money. A lot of indie hackers are would be happy with a business that makes 5-10k USD per month per founder
Many indie hackers are trying to avoid having a boss and/or trying to avoid selling time for money (as others have said), but some do want to grow relatively large businesses. I believe that DHH and Base Camp in general in its early days would have been considered “indie hackers”.
So other indie hackers will say that a specific part of a CRM, for example, is all that would be needed, they create that SaaS and sell it for $5 per month or free (a fraction of the price of an established brand). Rinse and repeat. It's easy because indie hackers appreciate small bugs and issues and are not as demanding as someone who is paying $50 per month, working with a large corporation that needs support 24/7 etc.