ArtCraft has released WordCraft, GridCraft and DeckCraft, Rust-based apps that aim to replace Microsoft Word, Excel and PowerPoint. The project follows ArtCraft's earlier work reimplementing software comparable to Adobe's Photoshop, and the GitHub development history lists "Claude Opus 5.5" as a co-author. The three apps reproduce the familiar Office way of working while also supporting AI-agent operation of documents and spreadsheets. But having a rich feature set is not the same as being able to edit and save an Office file received from a business partner without problems and send it back as is. Before these apps can serve as practical Office alternatives, significant challenges remain.
Three Rust apps that recreate Word, Excel and PowerPoint
WordCraft is a document editor with a ribbon interface, styles, tracked changes and more. GridCraft is a spreadsheet application with a formula bar and sheet tabs, and DeckCraft supports slide editing and presentations. All three aim for an experience close to Microsoft Office, and the developer says they can read and write Office file formats.
| App | Microsoft product it targets | Supported Office format | Main features the developer describes as implemented |
|---|---|---|---|
| WordCraft | Word | DOCX | Styles, tables, tracked changes, mail merge |
| GridCraft | Excel | XLSX | Formulas including dynamic arrays, pivot tables, charts |
| DeckCraft | PowerPoint | PPTX | Slide masters, animations, presenter view |
Sources: GitHub materials for WordCraft, GridCraft and DeckCraft. The table summarizes features described as implemented; it does not guarantee the same behavior or results as Microsoft Office.
The three apps share Rust code between desktop versions and browser versions that use WebAssembly. The source code is public, and users can choose either the MIT License or the Apache 2.0 License. WordCraft released version 0.3.0 on October 8, but the availability of an installable version does not mean it is complete enough for everyday work. According to the public roadmap dated October 7, WordCraft and GridCraft are in a pre-alpha stage aiming for their first alpha releases, and DeckCraft is described as being in early development.
ArtCraft uses a "clean-room" approach, reproducing functionality with its own code based on published specifications and the observed behavior of real software. WordCraft's development rules permit observing how Microsoft Word behaves when operated, but prohibit analyzing or disassembling its internal code. The project also does not reuse other companies' icons or templates, instead using materials it created itself or that are cleared for redistribution. For fonts specified in documents, the policy is to display them using fonts installed on the user's system or open alternative fonts with similar character widths. However, this is a policy the developer has stated publicly; it does not mean every part of the development process has been audited by a third party.
WordCraft's "87%" is not an Office document compatibility rate
According to WordCraft's roadmap dated October 7, commands corresponding to 354 of the 405 items in Microsoft Word's ribbon and menus have been implemented—about 87%. But when the extent to which each feature is reproduced and the fidelity of actual behavior are taken into account, compatibility with Word is estimated at about 62%. Both figures are the developer's own assessments, and neither means that 87% of DOCX files will be handled correctly.
The command implementation rate counts whether a mechanism for invoking a feature exists. For example, even if a table-insertion feature exists, a document containing complex tables will not necessarily paginate the way it does in Word. Even if footnotes can be displayed, showing a long footnote continuing onto the next page requires separate handling. In fact, the roadmap states that handling of footnotes that span pages and the feature for equalizing column heights are not yet implemented.
Even more important is how much of the original content can be preserved when a file is edited and saved. WordCraft's roadmap explicitly states that charts, SmartArt and OLE embedded objects in DOCX files are lost during loading and saving. It also says that validation—opening a variety of DOCX files actually used in business, displaying and re-saving them, and confirming that content and layout are preserved—has not yet begun. The developer lists this validation as one of the key challenges for the first alpha release. There is a large difference between being able to create simple text from scratch and being able to receive a complex report, edit it, and return it with its original formatting and content intact.
That said, the technical specifications needed to reproduce Office formats are public. Microsoft describes Office Open XML (OOXML) as an international standard under ECMA-376 and ISO/IEC 29500. DOCX, XLSX, PPTX and similar files are basically a combination of ZIP and XML. However, Microsoft's own compatibility explanations state that exchanging files correctly between different applications requires appropriate handling not just of the file format but also on the application side. In other words, even if an app can read files based on the public specifications, it will not necessarily display and edit a document's content and layout the way Word does.
Microsoft's SDK also carries a note that if some markup is removed by preprocessing done to ensure compatibility, only the content remaining after processing is saved. This does not mean ArtCraft uses that SDK. It illustrates that beyond supporting a file format, how unsupported elements are preserved requires separate design and validation.
Compatibility with Office must be assessed separately for documents, spreadsheets and presentations
GridCraft includes an engine that manages dependencies between formulas and recalculates only the parts affected by a cell change. It is also said to support dynamic arrays and pivot tables. However, according to the October 7 roadmap, the XLSX files that pass the load-and-resave tests are mainly files created by the development team. Validation using a variety of real-world Excel workbooks remains to be done. It is also necessary to confirm that no repair warning appears when a saved file is opened in Excel.
Organizing the challenges of reading, editing and re-saving Office files based on the roadmaps of the three apps gives the following picture.
| Use | Validation status and limitations described by the developer | What to check for business use |
|---|---|---|
| Editing documents in WordCraft | Comprehensive validation with real DOCX documents has not begun. Charts, SmartArt and OLE objects are lost | Whether the original content and layout can be preserved and returned to Word |
| Calculating and aggregating in GridCraft | Load-and-resave validated with self-made XLSX files. Validation with real business workbooks is still to come. VBA is outside the scope of development | Whether calculation results and formulas can be preserved. Whether required business processes can be run |
| Presentations in DeckCraft | PPTX fidelity validated only with self-made slides. WMA and WMV can be embedded but not played | Whether saved files open in PowerPoint. Whether effects, audio and video can be played during a presentation |
Sources: the roadmaps for WordCraft, GridCraft and DeckCraft. All are the developer's own assessments dated October 7, and the public materials were checked on October 9. They are not the results of independent validation of each app.
In this way, judging whether the apps can serve as Office alternatives requires separately checking the preservation of DOCX content and layout, the formulas and business functions of XLSX, and the re-saving of PPTX and behavior during presentations.
In GridCraft in particular, the stated approach is not to implement VBA as is, but to substitute a proprietary scripting feature that can record and edit operations. This does not mean existing Excel macros can be migrated unchanged. For features that depend on Microsoft's cloud services, such as co-authoring, the policy is either to provide open alternatives or to leave them out of scope. Users cannot currently get cloud services equivalent to Microsoft's. Some areas remain unsupported, including advanced data-import features equivalent to Power Query and subtle differences in formula behavior. GridCraft is said to support 258 of the 290 items in Excel's ribbon and menus, about 89%. But this figure alone does not show how much of an existing Excel workflow can be migrated.
One reason compatibility with Excel is difficult is that special behaviors remain today to maintain compatibility with past software. A representative example is date handling. According to Microsoft, Excel treats 1900 as a leap year to maintain compatibility with Lotus 1-2-3, a once widely used spreadsheet program. In reality, 1900 is not a leap year. However, correcting this behavior would shift dates in existing workbooks, so Excel still maintains it. Whether GridCraft reproduces this behavior correctly is unconfirmed, but developing a formula engine that can stand in for Excel requires reproducing not only mathematically correct results but also the behavior that existing Excel workbooks expect.
For DeckCraft, too, the developer estimates feature coverage at about 79% and fidelity including behavioral details at about 62%. Beyond validation with real PPTX files, there is also room for improvement in areas such as the presenter view and the animation editing interface. Being able to open slides, being able to open edited slides in PowerPoint without problems, and having animations and audio or video play correctly during a presentation each require different validation. Note that the lack of WMA and WMV playback does not mean all audio and video formats are unusable. The developer describes support for several formats, including MP3, AAC and H.264.
Claude took part in development, and the finished apps can also be operated by AI
What distinguishes ArtCraft's effort is that it not only uses AI to develop the software but also designs the finished apps themselves to be operated by AI agents.
WordCraft provides 389 commands, and in addition to the ribbon and keyboard operation, the same functions can be invoked from the command line and through MCP. MCP (Model Context Protocol) is a common protocol that lets AI agents work with external applications and tools. Using it, an AI agent can carry out operations such as opening a document, selecting text, changing formatting and saving. A feature for retrieving the document's structure is also provided, so the AI can confirm which part of a document it changed without relying only on how the screen looks.
GridCraft and DeckCraft likewise adopt a design in which human operation and AI-agent operation use common commands. Because the part responsible for screen display is separated from the engine that actually does the processing, processing can also run without showing the app window. This differs from using AI at the development stage, where Claude writes the app's code. It is a mechanism that lets AI agents such as Claude operate the finished app directly.
Possible uses include having AI tidy a report's formatting or aggregate spreadsheet data and create a chart. However, the fact that an AI can execute an app's commands correctly does not necessarily mean the resulting document or calculation is correct. And even if a document's internal structure has been changed correctly, its appearance on the page is not necessarily correct. For complex documents and slides in particular, the actual rendered result needs to be checked.
Similar caution is needed for Japanese documents. WordCraft says it supports Japanese IME input, but its roadmap lists support for complex scripts and improved localization as future challenges. Being able to type Japanese is different from sufficiently reproducing the features needed for Japanese document creation, such as vertical writing and line-breaking rules (kinsoku).
What ArtCraft needs to show next is the results of validation: how much content and formatting is preserved when real business documents and Excel workbooks are edited and re-saved. For DeckCraft as well, compatibility with PowerPoint and behavior during presentations need to be confirmed using real presentation materials. If these challenges are overcome, the apps could become a new option that keeps the familiar Office way of working while letting AI agents use the same functions. Whether they can develop beyond merely aiming to replace Office into applications where humans and AI share a common operating system—ArtCraft's effort is an intriguing attempt that also bears on how office software may evolve.