IANAL: Since the company offered to buy the software, they obviously don't think they have any claims on it. Of course, your legal position depends upon your l

IANAL: Since the company offered to buy the software, they obviously don't think they have any claims on it. Of course, your legal position depends upon your local jurisdiction. You don't say who is using your software. Is it your company's clients? Your company? Others?? How much are they saving, paying? First step is to establish a discounted cash flow monetary value of the benefits of your software. About 20% to 30% of that might be an appropriate price for it. This estimate depends on numerous factors which are beyond the scope of a HN reply. If the amount is much more than $10k, then you might have a viable business to establish a startup. In which case you should seek out competent legal advice and test the waters for potential investors. Or, you could consider $10k as the starting point for negotiations. Based on the above estimate of its value you could counter with a far larger price. In any negotiation the first amount discussed is simply the starting point. As a basic principle you never accept the first offer, but counter with something far above what you think is reasonable. If you are uncomfortable with such heavy negotiations, then you could pay a suitably experienced lawyer to negotiate on your behalf for say 15% of the final amount.