This happens quite a bit in many other service industries.
Like others said, stop doing any additional work. If you are hosting it right now, take it down. Even the demo.
Legally there isn't much you'll be able to do that won't cost you more than the amount they owe you. You can try small claims court in the county where the offense took place, so where you live. That's usually under $100 to file and have the defendant be served, depending where they live.
Unfortunately, this is part of business. I have seen many times where after 6 months..1 year...even 2 years later, the client comes back and now needs to finish it. This could be for many reasons, maybe the found somebody else and it was a shitty product and now they have to double down on their mistake. Either way, if they come back, get an upfront retainer! Plus all previous invoices they haven't paid of course. If I know a client is sketchy and they pay late or sometimes never, any additional work will always be paid upfront.
You would do well to have an accounting system you use. So If somebody owes you money, that is a balance on your accounts receivables. If they don't pay it, you can write it off as an expense of unpaid earnings. This has tax advantages, depending on your size and all. So possibly look into that. It's a good thing to have. Even if you are a sole freelancer, there are many free apps out there to do this.
Another suggestion is anytime you do work, have a client engagement letter. This type of thing is required in many service industries, accounting, law, etc. but it really is a good idea. Legally it may not help you at all, but it makes sure that the terms are more clear to the client and not just an oral agreement. It's a simple way to have something in writing rather than having an entire detailed contract. Which for bog jobs, I would definitely have a contract.
At the end of the day, learn from it, it will happen again, trust me, and move on.
Like others said, stop doing any additional work. If you are hosting it right now, take it down. Even the demo.
Legally there isn't much you'll be able to do that won't cost you more than the amount they owe you. You can try small claims court in the county where the offense took place, so where you live. That's usually under $100 to file and have the defendant be served, depending where they live.
Unfortunately, this is part of business. I have seen many times where after 6 months..1 year...even 2 years later, the client comes back and now needs to finish it. This could be for many reasons, maybe the found somebody else and it was a shitty product and now they have to double down on their mistake. Either way, if they come back, get an upfront retainer! Plus all previous invoices they haven't paid of course. If I know a client is sketchy and they pay late or sometimes never, any additional work will always be paid upfront.
You would do well to have an accounting system you use. So If somebody owes you money, that is a balance on your accounts receivables. If they don't pay it, you can write it off as an expense of unpaid earnings. This has tax advantages, depending on your size and all. So possibly look into that. It's a good thing to have. Even if you are a sole freelancer, there are many free apps out there to do this.
Another suggestion is anytime you do work, have a client engagement letter. This type of thing is required in many service industries, accounting, law, etc. but it really is a good idea. Legally it may not help you at all, but it makes sure that the terms are more clear to the client and not just an oral agreement. It's a simple way to have something in writing rather than having an entire detailed contract. Which for bog jobs, I would definitely have a contract.
At the end of the day, learn from it, it will happen again, trust me, and move on.