When building in public, is copying a feature a license violation or fair game?

A public accusation on X between two indie founders over a copied feature has ignited a debate about open-source ethics, AGPL licenses, and the unwritten rules of competition.

Where it happened

The dispute began on June 26, 2026, in a thread on X started by Momen (@mfts0), the founder of Papermark, an open-source DocSend alternative. He directly accused Nico Burns (@nicoburns_), founder of a competing service, of copying code. The thread, containing screenshot comparisons of code and UI, drew responses from both founders and the wider developer community.

Side A: An accusation of code theft and license violation

Momen’s position is that Nico Burns directly copied significant portions of Papermark’s codebase for a new "data room" feature. Papermark is licensed under AGPL 3.0, which requires derivative works to also be open-sourced under the same license. Momen alleges this did not happen. His evidence consists of side-by-side screenshots showing striking similarities in UI components, file structure, and specific code snippets. He argues this goes beyond inspiration, stating, "Hey Nico, you didn't vibe code your data room but stole it from Papermark." For Momen and his supporters, this is a clear case of intellectual property theft and a violation of the open-source license, undermining the trust inherent in the "build in public" movement. The core of the argument is that using an AGPL project as a reference without adhering to its share-alike terms is not legitimate competition.

Side B: A defense of inspiration and parallel development

Nico Burns frames his work as independent development within a competitive market. He denies directly copying code and attributes the similarities to industry-standard practices and shared tools. In his replies, he argues that many products in the space look similar because they solve the same problem and are often built with the same popular component libraries, like Shadcn UI and Next.js. His defense suggests that Papermark itself is built upon a foundation of open-source projects, and creating a similar feature is a normal part of competition. The argument is that observing a competitor's public product for inspiration is standard practice. Any resemblance, from this perspective, is convergent evolution rather than plagiarism, a result of two developers independently arriving at similar solutions using a common tech stack.

What's underneath

This conflict highlights the inherent tension in the "build in public" ethos, especially when combined with permissive or copyleft open-source licenses. The debate isn't just about whether code was copied. It's about the blurry line between inspiration and infringement in a development culture that prizes transparency and shared tooling. Both sides operate in a world where Next.js, Vercel, and Shadcn UI create a common design and architectural language, making products naturally look and feel similar. The dispute forces a difficult question: at what point does "learning from" a public repository become "deriving from" it in a way that legally triggers the obligations of a license like AGPL?

The investor read

This incident serves as a cautionary tale about the operational risks of the "build in public" strategy, particularly for companies using copyleft licenses like AGPL. The ease of replication using modern frontend frameworks can diminish a startup's defensibility if its primary moat is its user interface or specific features. For investors, this highlights the increasing importance of intellectual property strategy, even at the earliest stages. It signals a potential shift where founders may become more guarded, adopt more restrictive licenses, or focus on moats beyond easily replicable code, such as community, brand, and proprietary data integrations. Diligence on license compliance for key dependencies is becoming non-negotiable.

Pull quote: “Hey Nico, you didn't vibe code your data room but stole it from Papermark.”