There are numerous useful apps, software programs, web applications, browser plug-ins, etc., that have been produced by individual programmers. Are these programmers exposing themselves to personal liability risks by making their tools available to the public?

For example, consider a hypothetical case where an individual programmer in the US has developed a web-based service that is used for business. Unbeknownst to the programmer, there is a bug in the code. The bug surfaces when a user attempts to use the service, costing the user a large sum of money because the service failed due to the bug. How likely would it be for the developer of the service to be found liable for the damages that the user of the service incurred, if the user of the service attempted to sue the developer? Does the answer depend on whether or not the developer charges for the use of the service?

  • I think it all depends on the license or the terms of service. The GNU GPL license for example says the program is provided "as is, without warranty of any kind, either expressed or implied, etc." There is only one thing I've always wondered: in statements like "there is no warranty for the program, to the extent permitted by applicable law", what that part about the applicable law means and what it actually implies. – reed Nov 30 '18 at 22:04
  • It also depends on the nature of "unbeknownst to the programmer". Coding that requires impossible knowledge of the working of the black box to work correctly may not give rise to negligence, because it was unforeseeable that the OS / machine would react in a particular way to an input. – user6726 Dec 1 '18 at 0:25
  • Thanks to everyone that answered and commented for the helpful responses. These responses prompted the obvious follow-up question, about what a programmer can do to protect himself/herself from these liability risks. See: law.stackexchange.com/questions/34054/… – weaver Dec 4 '18 at 16:41
  • Is there a case of an actual lawsuit against a programmer for open source software, or software made available to the public by some other license? I haven't heard of one. – David Thornley Dec 4 '18 at 18:33



If a developer charges for a program they have a contract. Common law implies terms into contracts that the goods and services provided will be merchantable (that is suitable for sale) and fit for purpose (that is they do what the provider says they do or that the customer specified). Depending on local consumer protection law these may or may not be excludable by explicit terms.


Notwithstanding the existence of a contract, there may be a claim in the tort of negligence. To prove negligence the recipient must show:

  1. The developer owed a duty of care to the user
  2. They failed in that duty
  3. As a result of that failure the user suffered harm that was reasonably foreseeable to the owners.

All of these are fact dependent. Things that are all relevant would be if there is a contract, the specificity of the tool, any disclaimers etc.

Consumer Protection Law

These vary by jurisdiction. In many cases they imply non-excludable warranties on “suppliers” - so they encompass people who supply goods and services without charging for them.

Health and Safety Law

If the app has direct safety implications (e.g. if it modified a car’s computer control system) then the supplier is obliged to ensure that it is safe.

  • How much of this would apply to software released to the public in general, such as under an open source license? That involves no contract, and I don't see that the developer would owe a duty of care to any random member of the public. I haven't seen effective warranties for software quality, and open source software is not normally used to modify embedded software by the developer, so would these apply? – David Thornley Dec 4 '18 at 18:31
  • @DavidThornley all of it except contract law – Dale M Dec 4 '18 at 20:03

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