Photoshop Rebuilt in Four Weeks – What Is Still Protected in Software?

At the end of September 2026, a well-known developer initially published seven free open-source programs on GitHub under the name “ArtCraft”, designed as alternatives to Photoshop, Illustrator, Premiere, Lightroom, After Effects, InDesign and Acrobat. In mid-October 2026, this was followed by recreations of Word, Excel and PowerPoint.

The programs were developed in Rust with the assistance of Anthropic’s Claude AI model. The stated objective is complete functional equivalence with the original products, including familiar layouts and workflows. The developer describes the approach as a “clean-room reimplementation” without Adobe code, while some media reports refer to AI-assisted reverse engineering.

The case illustrates just how significantly AI agents can reduce the effort required to recreate complex software. This makes a question previously addressed mainly in principle-based legal decisions into a practical issue for software providers: Which parts of a program are protected against imitation if the code itself is not copied at all?

Does Copyright Law Protect Against Functionally Identical Reproductions?
The Code Is Protected, Not the Functionality

Computer programs are protected under Sections 69a et seq. of the German Copyright Act (UrhG). Pursuant to Section 69a(2) UrhG, protection covers all forms of expression of a program, while the ideas and principles underlying any element of a program are expressly excluded. In its SAS Institute judgment (judgment of 2 May 2012 – C-406/10), the CJEU concluded that neither the functionality of a program nor the programming language or the format of data files is protected as a computer program. In its judgment of 17 October 2024 (C-159/23, Sony Computer Entertainment Europe), the CJEU confirmed that protection applies to source code and object code. Merely modifying variables in a computer's memory, without reproducing or altering the code, does not fall within the scope of protection.

For ArtCraft, this means that a program providing the same functions using its own code in a different programming language does not infringe copyright solely because its functionality is identical.

Observation Is Permitted, Decompilation Only Within Strict Limits

Anyone entitled to use a program may observe, study and test its functioning in order to identify the ideas and principles underlying it (Section 69d(3) UrhG). This right cannot be excluded by contract either (see Section 69g(2) UrhG).

Decompilation, i.e. converting  object code back into source code, is subject to considerably stricter limitations. Section 69e UrhG permits it only to the extent that it is indispensable for achieving interoperability with an independently created program. The information obtained may expressly not be used to develop a program with substantially similar expression (Section 69e(2) No. 3 UrhG).

This makes the development history of ArtCraft the decisive question. If the AI model worked with publicly available documentation, disclosed file formats (Adobe, for example, publishes a specification of the PSD format) and observed program behaviour, there are strong grounds for considering the approach permissible. By contrast, if the object code of the original programs was decompiled in order to recreate them, this would exceed the limits of Section 69e UrhG.

There is also a contractual dimension. Adobe's and Microsoft's terms of use prohibit using their products to replicate their functionality. Such clauses are binding only on contracting parties and, in Germany, must be assessed against Sections 69d and 69g UrhG as well as Section 307 of the German Civil Code (BGB).

User Interface and Design

A graphical user interface is not a form of expression of a computer program and therefore does not fall within the scope of Sections 69a et seq. UrhG. However, it may qualify for protection as an independent work if it constitutes its author's own intellectual creation (CJEU, judgment of 22 December 2010 – C-393/09, BSA). According to the CJEU, elements dictated solely by their technical function do not meet this criterion.

Reproducing an interface with familiar layouts therefore involves a grey area: the usual arrangement of toolbars, layers and menus is likely to be predominantly dictated by functional requirements, whereas individually designed icons and graphic elements are less likely to be. In addition, registered designs under the German Design Act (DesignG) and registered EU designs may be relevant for icons and screen layouts.

Unfair Competition Law as the Key Legal Avenue

If the code is not copied but the recreated programs are marketed under their own names, the dispute shifts towards unfair competition law. The German Act Against Unfair Competition (UWG) does not protect the program as such. Instead, it focuses on how a reproduction is created and presented on the market.

The provisions of the UWG require a commercial practice, which cannot be taken for granted in the case of a free open-source project. However, ArtCraft's development is reportedly financed through the provider's commercial token business, which may indicate a commercial connection.

Protection Against Imitation under Section 4 No. 3 UWG

As a general rule, reproducing a product that is not protected by an specific intellectual property right is permissible (German Federal Court of Justice (BGH), judgment of 28 May 2009 – I ZR 124/06, LIKEaBIKE). A reproduction becomes impermissible only when two conditions are met. First, the original product must stand out from comparable products to such an extent that users associate it with a particular manufacturer (so-called competitive individuality). Second, the reproduction must have been created or marketed in an unfair manner. The degree of competitive individuality, the extent of imitation and the other circumstances interact: the closer the reproduction is to the original, the lower the requirements for the other elements.

In the context of software, the question arises as to which characteristics can establish such competitive individuality in the first place. According to the BGH, characteristics that are technically indispensable cannot establish protection. By contrast, designs that serve a technical function but could also have been designed differently may qualify for protection (judgment of 22 January 2015 – I ZR 107/13, Exzenterzähne). Functions, file formats and industry-standard tools such as layers or brushes are therefore generally free for others to use. The specific appearance of an interface, however – including colours, icons and a distinctive arrangement of controls – may indicate the manufacturer of the product.

The law identifies three situations in which a reproduction is unfair. Misleading users as to the commercial origin of a product under Section 4 No. 3(a) UWG occurs if users believe that the program originates from Adobe or an official partner and the provider could have prevented this confusion with reasonable effort. Distinct product names such as PhotoCraft speaks against such deception. However, if the interface looks almost identical to the original, a different name alone may not be sufficient.

It is also impermissible to exploit the reputation of the original product (Section 4 No. 3(b) UWG). It is not enough for the reproduction merely to evoke associations with the original (BGH, judgment of 2 December 2004 – I ZR 30/02, Klemmbausteine III). The reputation must be deliberately transferred to the provider's own product, for example through advertising that relies on Photoshop's reputation.

Finally, it is impermissible to obtain the knowledge used for the reproduction through dishonest means (Section 4 No. 3(c) UWG). This brings us back to the development history. If the original programs' code was decomplied in breach of Section 69e UrhG, this would likely be considered dishonest.

Misleading Commercial Practices under Section 5 UWG

In addition to protection against imitation, the impression created by the reproductions among the public is relevant. Under Section 5(3) No. 1 UWG, marketing is misleading if it creates a likelihood of confusion with a competitor's goods or trade mark. This may be particularly relevant where well-known program icons are adopted. In relation to well-known logos, the BGH has held that they may create the impression of an association with the owner of the logo (BGH, judgment of 15 August 2013 – I ZR 188/11, Hard Rock Café). The same is likely to apply to software icons.

Statements about the product itself may also be misleading (Section 5(2) No. 1 UWG). If ArtCraft advertises “complete functional equivalence”, a “clean-room” reproduction without third-party code or full compatibility with Photoshop files, these claims must be accurate. If important functions are missing, files are only partially rendered correctly or third-party code is in fact incorporated into the program, such claims are impermissible.

Comparative Advertising under Section 6(2) No. 6 UWG

Section 6(2) No. 6 UWG establishes a separate boundary for comparative advertising, i.e. advertising that identifies a competitor or its product. Such advertising is unfair if it presents a product as an imitation or reproduction of goods marketed under a protected trade mark.

The CJEU interprets this prohibition broadly (judgment of 18 June 2009 – C-487/07, L'Oréal/Bellure). According to the CJEU, the prohibition covers not only counterfeits but any advertising that expressly or implicitly conveys that a product is an imitation. A likelihood of confusion is not required, and the advantage obtained in this way is considered an unfair exploitation of the reputation of the trade mark.

The BGH interprets the provision more narrowly. Merely claiming that a product is equivalent is not sufficient; rather, the advertising itself must clearly indicate that the product is an imitation (judgment of 6 December 2007 – I ZR 169/04, Imitationswerbung). Terms such as “similar” or “like” are generally insufficient on their own (judgment of 2 April 2015 – I ZR 167/13, Staubsaugerbeutel im Internet).

The prohibition is particularly relevant for software reproductions because it requires neither competitive individuality nor deception as to commercial origin. The dividing line lies in the wording used. References to compatibility or describing a product as an “alternative to Photoshop” are likely to be permissible as claims of equivalence. By contrast, terms such as “Photoshop clone” or comparisons along the lines of “PhotoCraft = Photoshop” should be viewed more critically. The fact that ArtCraft is described in media reports as a free reproduction of the Adobe suite is irrelevant in this respect; what matters is the provider's own advertising.

What Companies Should Review Now

The case gives rise to different implications depending on the role of the company:

• Software providers should not rely exclusively on copyright protection of their code. For protection under unfair competition law, the key questions are whether the interface contains design features that indicate commercial origin and are not technically predetermined, and how well-known the product is. Additional protection may be available through registered designs, trade mark protection (including for program icons) and effective provisions governing reverse engineering in licence terms.
• Companies considering the use of free software reproductions assume the associated risks without any warranty and without indemnification against third-party claims. There are also IT security concerns when using unverified, AI-generated code.
• Anyone using AI agents themselves to reproduce functions of competitors' products should document the development process: which sources were provided to the model, that no object code was decompiled, and which checks were carried out for third-party code and applicable licences. Equally important are distinctive product identification and interface design, as well as advertising that focuses on compatibility rather than imitation.

New Tools, Familiar Boundaries

From a legal perspective, the ArtCraft case is less novel than the headlines might suggest. European copyright law has always protected the code, not the underlying idea. AI primarily changes how quickly and inexpensively these boundaries can be tested.

For providers of the original products, this shifts the focus towards unfair competition law. Whether a reproduction is permissible depends on the individual circumstances: how extensively the interface has been adopted and, above all, how the product is advertised.

Questions remain open as to the extent of protection afforded to user interfaces and how the origin of AI-generated code can be established.