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, a figure marked disputed. The developer says it implements about 98% of Excel's worksheet functions.
| Figure | Value | Note | Claim |
|---|---|---|---|
| Excel ribbon and menu commands GridCraft implements | 89% | 6 | |
| GridCraft real-work ready | 50% about | disputed | 16 |
| Excel worksheet functions | 98% about | 6 |
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
- What's now possible 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.
- What doesn't add up contradiction GridCraft's reported command coverage sits 39 points above its reported readiness, so 'implemented' cannot be read as 'usable'.
- Who has to decide decision Anyone weighing a move off Office has to run their own documents through these alphas, because the percentages are self-reported and untested.
- What it sets up 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.
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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% [15] sits 19 to 29 points below the per-app coverage figures of 79% to 89% [13].
DeckCraft's 79% is about 151 of 191 PowerPoint features, so roughly 40 are still missing [12]. Its readiness estimate of about 55% [16] is 24 points under its feature figure [14].
Every one of these figures is self-reported. Thomas supplied GridCraft's 89% and 98% [6], the DeckCraft GitHub page supplies the 79% [7], and the project supplies the 60% [15]. 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 [9].
The engineering that is visible is real. WordCraft reads and writes .docx, handles .odt, .rtf, .html, .md and .txt, and imports legacy .doc [5]. It also implements track changes and mail merge [10]. The project deserves credit for publishing readiness estimates that undercut its own command counts [16].
The WordCraft page calls the project an "open-source, clean-room reimplementation of Microsoft Word" [3]. 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 [17] and that he answered "AI slop" criticism on X by saying he knows how to code [18]. Its own verdict is that most of these apps are still far from what they intend to replace [2].
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
- Evidence40
- Adoption20
- Hype gap+30
- Incentives55
- Confidence60
Perspective Coverage
4 publishers- Builder
- Builder 33%
- Operator
- Operator 30%
- Investor
- Investor 37%
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]
Most of these apps are still far from what they intend to replace.
- [3]
According to its GitHub page, WordCraft is an "open-source, clean-room reimplementation of Microsoft Word".
- [4]
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.
- [5]
WordCraft reads and writes .docx and supports .odt, .rtf, .html, .md and .txt, and can import the legacy .doc format.
- [6]
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.
- [7]
DeckCraft's GitHub page claims 79% feature parity across 191 PowerPoint features.
- [8]
WordCraft is the furthest along of the three, with 88% of Word's ribbon-based commands implemented.
- [9]
GridCraft uses .xlsx as its native file format and is fully scriptable by AI agents.
- [10]
WordCraft offers the same ribbon, styles, tables, track changes and references as Word, and implements features like mail merge.
- [11]
GridCraft's reported readiness (about 50%) is 39 percentage points below its reported ribbon and menu command coverage (89%).
- [12]
79% of DeckCraft's 191 PowerPoint features is about 151 features, leaving about 40 unimplemented.
- [13]
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).
- [14]
DeckCraft's reported readiness (about 55%) is 24 percentage points below its reported feature parity (79%), though the two figures count different things.
- [15]
Overall, the project estimates it has reached around 60% feature parity with the Microsoft app.
- [16]
All three apps are in alpha, with GridCraft around 50% 'ready for real work' and DeckCraft around 55%.
- [17]
Brandon Thomas is a software engineer with 15 years of experience.
- [18]
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.
- [19]
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.
Sources
4 independent publishers whose own reporting we read for this story.
- decrypt.coDeveloper Who Cloned Photoshop With AI Just Did the Same to Microsoft Office
1 article · October 14, 2026
- futurism.comWord, Excel and PowerPoint
1 article · October 14, 2026
- techspot.comThe developer who cloned Photoshop using AI has now created Word, Excel, and PowerPoint replicas with Claude
1 article · October 13, 2026
- tomshardware.comCreator of free Adobe clones unveils open-source Microsoft Office Excel, PowerPoint, and Word replications
1 article · October 11, 2026
Topics and entities
Topics
- Office Productivity Software
- Open source software
- Software Subscription Pricing
- AI-generated software