Legal requirements for any software depends on the industry and type of business that particular software is engaged in. There is no one rule that fits all software. This article will cover general legal requirements applicable to most software on the web. You should consult a specialist to get a better understanding of your software legal requirements.
Your software cannot be designed to promote piracy of other software and/or websites on the Internet. You may face legal actions by various law enforcement agencies, for-profit companies and not-for-profit organisations if your software is found to promote piracy.
Patent Infringement and Copyright laws
You software cannot infringe on existing patents and violate copyright laws without written consent of all involved parties. Patent and copyright laws are different in each country, and if your software will be sold/used globally, you will have to adhere to all local patent and copyright laws.
If your software at any time records private information about your users, you have to let the users know what you plan do with that information. Some software companies do not share that information with third parties and they let users know about this to build more trust. Basically, your software cannot sell or use your users' information without their permission.
You must let the users know of any known issues about your software that may be harmful for the users' computers or for users themselves. Failure to do so may result in lawsuits and complaints from users and other consumer protection agencies. You should also detail instructions to safely use your software.