BuildIndependently confirmed2 publishers2 min readPublished
Brandon Thomas's Claude-built Office clones rate themselves at about 60% feature parity
Developer Brandon Thomas built WordCraft, GridCraft and DeckCraft, early open-source clones of Word, Excel and PowerPoint, with Claude. TechSpot reports the project's own estimate at about 60% feature parity, with GridCraft about 50% ready for real work.
The Engineer · Build desk
Key figures for GridCraft, the Excel clone. The developer says it implements 89% of Excel's ribbon and menu commands. The project estimates it is about 50% ready for real work. The developer says it implements about 98% of Excel's worksheet functions.
| Figure | Value | Note | Claim |
|---|---|---|---|
| Excel ribbon and menu commands GridCraft implements | 89% | 8 | |
| GridCraft real-work ready | 50% about | 3 | |
| Excel worksheet functions | 98% about | 8 |
What happened
- The apps are written in Rust with Anthropic's Claude Opus 5.5, according to TechSpot, and are released under MIT or Apache 2.0 licenses.
- WordCraft runs natively on Windows, macOS, Linux and BSD, and in the browser through WebAssembly, from one Rust codebase with no Electron or Tauri.
- The developer says GridCraft implements 89% of Excel's ribbon and menu commands and about 98% of its worksheet functions.
- DeckCraft's GitHub page claims 79% feature parity across 191 PowerPoint features.
Why it matters
- capability By the developer's own count, function coverage is no longer what holds an Excel clone back, and in our view the open question is behavior on real files.
- contradiction GridCraft's reported command coverage sits 39 points above its reported readiness, so 'implemented' cannot be read as 'usable'.
- decision Anyone weighing a move off Office has to run their own documents through these alphas, because the percentages are self-reported and untested.
- precedent Tom's Hardware says CADcraft is commonly discussed among 3D printing and engineering users, so CAD software looks like the next category to face the same coverage-versus-readiness test.
The release carries two kinds of number: coverage, which counts what exists, and readiness, which is a judgement about whether it works. The overall parity estimate of around 60% [2] sits 19 to 29 points below the per-app coverage figures of 79% to 89% [17].
DeckCraft's 79% is about 151 of 191 PowerPoint features, so roughly 40 are still missing [19]. Its readiness estimate of about 55% [3] is 24 points under its feature figure [18].
Every one of these figures is self-reported. Thomas supplied GridCraft's 89% and 98% [8], the DeckCraft GitHub page supplies the 79% [9], and the project supplies the 60% [2]. For the 98% to describe your workbooks, each function would have to return what Excel returns on your inputs, and the file would have to survive a round trip through .xlsx, GridCraft's native format [14].
The engineering that is visible is real. WordCraft reads and writes .docx, handles .odt, .rtf, .html, .md and .txt, and imports legacy .doc [7]. It also implements track changes and mail merge [15]. The project deserves credit for publishing readiness estimates that undercut its own command counts [3].
The WordCraft page calls the project an "open-source, clean-room reimplementation of Microsoft Word" [5]. The sources do not describe how that clean-room process was run when Claude wrote the code. Tom's Hardware reports that Thomas has 15 years of experience as a software engineer [11] and that he answered "AI slop" criticism on X by saying he knows how to code [12]. Its own verdict is that most of these apps are still far from what they intend to replace [4].
What to watch
- An outside test of .docx, .xlsx and .pptx round trips on real documents, which would replace the self-reported percentages.
- A published readiness estimate for WordCraft, to set beside GridCraft's 50% and DeckCraft's 55%.
- Whether Thomas starts CADcraft, the project Discord members keep raising.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence35
- Adoption
- Insufficient
- Hype gap+15
- Incentives
- Insufficient
- Confidence55
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
WordCraft, GridCraft and DeckCraft are written in Rust with Anthropic's Claude Opus 5.5, as the Adobe replicas were, and are available for download under MIT or Apache 2.0 licenses.
- [2]
Overall, the project estimates it has reached around 60% feature parity with the Microsoft app.
ReportedSupportedSource: TechSpot, citing the project's estimate2 sources— create a free account to open themView cited source - [3]
All three apps are in alpha, with GridCraft around 50% 'ready for real work' and DeckCraft around 55%.
ReportedSupportedSource: TechSpot, citing the project's estimate2 sources— create a free account to open themView cited source - [4]
Most of these apps are still far from what they intend to replace.
ReportedSupportedSource: Tom's Hardware2 sources— create a free account to open themView cited source - [5]
According to its GitHub page, WordCraft is an "open-source, clean-room reimplementation of Microsoft Word".
- [6]
WordCraft runs natively on Windows, macOS, Linux, and BSD, can also be used in the browser via WebAssembly, and uses a single Rust codebase for all platforms without falling back on Electron or Tauri.
- [7]
WordCraft reads and writes .docx and supports .odt, .rtf, .html, .md and .txt, and can import the legacy .doc format.
- [8]
GridCraft, which replicates Microsoft Excel, already implements 89% of Excel's ribbon and menu commands and about 98% of its worksheet functions, according to the developer.
- [9]
DeckCraft's GitHub page claims 79% feature parity across 191 PowerPoint features.
- [10]
WordCraft is the furthest along of the three, with 88% of Word's ribbon-based commands implemented.
- [11]
Brandon Thomas is a software engineer with 15 years of experience.
- [12]
After ArtCraft became popular, many criticisms followed about vibecoded software and AI slop, and Thomas responded on his X account that he does know how to code.
- [13]
ArtCraft's Discord community keeps recommending other software it would like to see, with CADcraft commonly discussed among 3D printing and engineering enthusiasts who dislike Autodesk.
- [14]
GridCraft uses .xlsx as its native file format and is fully scriptable by AI agents.
- [15]
WordCraft offers the same ribbon, styles, tables, track changes and references as Word, and implements features like mail merge.
- [16]
GridCraft's reported readiness (about 50%) is 39 percentage points below its reported ribbon and menu command coverage (89%).
- [17]
The project's overall parity estimate of around 60% is 19 to 29 points below the per-app coverage figures: 79% (DeckCraft), 88% (WordCraft) and 89% (GridCraft).
- [18]
DeckCraft's reported readiness (about 55%) is 24 percentage points below its reported feature parity (79%), though the two figures count different things.
- [19]
79% of DeckCraft's 191 PowerPoint features is about 151 features, leaving about 40 unimplemented.
Sources
2 independent publishers whose own reporting we read for this story.
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Topics
- Office Productivity SoftwareFollow
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