If a mobile/web developer creates an application like Uber, then sells it to a company, and the company also wants the copyrights for the application, what happens if after few months another company comes to developer and asks for a new similar application like Uber, then the developer creates a new application like Lyft and give it to the new customer/company?

I mean a developer may use 90% of similar codes that he used while creating Uber application for the Lyft application. In this case, can Uber company sue against the developer because they have also bought copyrights for the Uber application?

It's a little bit confusing for me as a developer because most of the time we use similar codes to create similar behaviors in an application. Also the way you code is like your handwritten and you can not code similar applications in different ways, it's kinda meaningless! Because most of the time we just copy and paste similar codes that we already use in another application if we want to build something similar.

So how does copyrights law work for the applications?

  • 5
    That will depend on your contract, basically whether you sell a license to Uber or work for hire (e.g. are employed by them). Also, the answer might depend on the legislation.
    – PMF
    Apr 12, 2023 at 20:16
  • 1
    Generally, a contractor wouldn't just hand over the code the moment its finished and bail, but rather the contract would require them to support the code by fixing defects, OS updates, customer changes, etc. for a a period of years, often with an option to renew. Their contract would demand exclusivity/non-compete during their entire engagement.
    – user71659
    Apr 14, 2023 at 5:13
  • 6
    What does this have to do with mobile/web? Won't the same question apply to "regular" desktop applications?
    – Heinzi
    Apr 14, 2023 at 13:22
  • 1
    Maybe a little bit off topic. But I would carefully check the contract, a non competition clause might create more problems than a clause about the copyright.
    – FluidCode
    Apr 15, 2023 at 15:25
  • @PMF in the hypothetical, the developer created the first application and then sold it. This implies that the rights were sold outright, though it could also be a license. It's certainly not a work for hire.
    – phoog
    May 13, 2023 at 21:02

2 Answers 2


A fundamental principle of copyright law is that protection is only afforded to the concrete expression, and not the abstract idea. Therefore, if you write a sort program, what is protected is "that specific program", and not the general idea of a sort program. There are many kinds of sort algorithms: if you write a bubble sort program, you don't "own" all bubble sort programs, you only own the one that you wrote. If you sell your right to a particular bubble sort program, you don't thereby prevent yourself from writing another bubble sort program. But, technically, you do prevent yourself from copying that program, changing some variable names or maybe manually recoding a couple of lines, and re-licensing the code (assuming that you fully transferred copyright, or gave the customer exclusive rights to the code).

The basic question that the courts will ask is "did you copy that program", which they answer by looking at the similarity between the two programs. All bubble sorts have a necessary similarity. To prove infringement, the plaintiff would (ultimately) have to prove that the similarity had to have come from copying rather than independent coincidental re-creation. Functional considerations and general programmer practice would tend to weigh against an allegation of infringement in certain cases, where "counter" is a common name for a counter variable, and bubble sort is a well known algorithm with limited practical differences in lines of code.

The hard part is establishing that it would be natural for such similarities to exist even when independently coded by a single person. It may be common practice to take a program that you've sold and tweak it in some fashion, but that is copyright infringement, whereas "applying the lessons that you learned in writing X to a new program" is not infringement, it is using the same ideas, and the ideas are not what is protected.

  • 10
    Distinguishing between a tweaked copy and a newly written program might be hard for a bubble sort routine coded by the same person in the same programming language, but easy for an application of the size suggested in the OP. It would be easy for an expert witness to establish the percentage of content copied in bulk even if they received just the latest source code of both websites and not the respective source control histories, and even if the developer applied common refactoring tools plus a modest additional obfuscation effort to make the fact of bulk copying less obvious. Apr 13, 2023 at 13:20

If the developer sold exclusive rights to their code, their customer has grounds to sue.

If the developer licensed their code non-exclusively, there isn't grounds.

Normally, a contract developer will sell the rights, while a product-based company will license them. Of course it's common in practice to do the former, but then reuse parts of the code - there are both legal and non-legal ways to make this happen.

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