AI-Coded Open-Source Apps Take Aim at Microsoft Office

Preface

After releasing free applications modeled on Adobe’s creative software, developer Brandon Thomas has taken on another familiar subscription suite: Microsoft Office. His new open-source projects—WordCraft, GridCraft, and DeckCraft—are designed as alternatives to Word, Excel, and PowerPoint, with development assistance from Anthropic’s Claude. The apps are written in Rust and aim to work across desktop operating systems as well as in a browser.

Their release raises a practical question for people who rely on office software: can a rapidly built, free alternative handle the documents, spreadsheets, and presentations that real work demands? The projects already report substantial feature coverage, but their developers describe them as works in progress. Feature similarity is not the same as proven reliability, particularly when compatibility, stability, and complex files matter.

Lazy bag

WordCraft, GridCraft, and DeckCraft are free, open-source office applications built with Rust and Claude’s assistance. The developers report that WordCraft covers 88% of Word’s ribbon features, while GridCraft supports 513 of Excel’s 523 worksheet functions. DeckCraft covers about 79% of PowerPoint’s features and 93% of its core features. Despite those figures, the team estimates that WordCraft is about 60% ready for real work and GridCraft about 50% ready. The key takeaway: these projects show how quickly AI-assisted development can produce familiar software, but they are not yet established replacements for Microsoft Office.

Main Body

Brandon Thomas, the developer behind the ArtCraft project, has published three open-source applications intended to mirror Microsoft’s main office tools. WordCraft targets Microsoft Word, GridCraft targets Excel, and DeckCraft targets PowerPoint. Their source code is available on GitHub, where users can inspect, copy, and modify it. The projects use the MIT and Apache 2.0 licenses, which allow reuse, including commercial reuse, subject to each license’s terms.

The Office projects follow Thomas’ ArtCraft applications, which were designed as free counterparts to Adobe products including Photoshop, Illustrator, Premiere, and Lightroom. That earlier release drew attention as part of a broader wave of AI-assisted software cloning. Thomas has said the work was motivated in part by Adobe’s cancellation fee. The office applications extend the same approach from creative tools to software used for documents, calculations, and presentations.

All three applications are written in Rust, a programming language often chosen for performance and safeguards against certain memory-related errors. The project uses a shared codebase intended to run natively on Windows, macOS, Linux, and BSD, as well as in a web browser. That breadth could make the tools accessible to people using different operating systems, although platform support alone does not establish that every feature will behave consistently across them.

Thomas describes the applications as clean-room rebuilds. In this approach, developers work from public file-format specifications and observations of how the original applications behave rather than copying Microsoft’s source code. A clean-room method has a historical precedent: Compaq used a similar legal strategy to reproduce IBM’s PC BIOS, the basic startup software used by early personal computers, in the 1980s. The method is relevant because it distinguishes independent implementation from direct reuse of proprietary code.

WordCraft can read and write .docx, the file format used natively by Word. Its developers report coverage of 88% of Word’s ribbon features—the tabs and controls displayed across the top of the application. The feature list already includes track changes, footnotes, citations, and mail merge. Mail merge uses information such as names from a spreadsheet to personalize documents, for example by preparing multiple individually addressed letters.

However, feature counts do not capture every measure of practical compatibility. The team estimates that WordCraft is about 60% of the way to replacing Word for real work when file fidelity and stability are taken into account. The application is still labeled alpha, a development stage in which users should expect bugs and incomplete behavior. Before beta, its roadmap calls for testing with real-world .docx files, improving support for charts and SmartArt that remain intact after saving, bringing page layout closer to Word’s, conducting a stability review, and adding native printing.

An early hands-on account described WordCraft as a 91Mb download that felt responsive and looked similar to Microsoft Word. That experience suggests that the interface may be familiar to existing Office users, but a brief trial cannot settle whether the application is suitable for all everyday or professional tasks. Document fidelity, printing, layout, and reliable handling of varied files are essential parts of a word processor’s usefulness.

GridCraft, the spreadsheet application, reportedly supports 513 of Excel’s 523 worksheet functions. These functions include formulas such as SUM and VLOOKUP, which let spreadsheets calculate totals, find values, and process data. GridCraft also covers 89% of Excel’s ribbon commands. Its developers nevertheless estimate that it is about 50% ready for real work. Compatibility with real-world .xlsx files remains a planned area of work, so broad formula support does not guarantee that a complex business spreadsheet will open, calculate, and display exactly as expected.

DeckCraft is intended to serve as a PowerPoint alternative. Its GitHub page reports coverage of about 79% of PowerPoint’s features and 93% of its core features. It can open and save .pptx files, run transitions and animations, and export presentations to PDF. Unlike the other two applications, it has not yet reached its first alpha release. The reported feature coverage is therefore an indication of development progress, not evidence that the complete application is ready for routine use.

A notable design choice connects the apps to AI agents. Each button can also function as a command that an agent can invoke. The applications integrate through MCP, or the Model Context Protocol, a standard created by Anthropic to help AI models interact with external tools. In principle, a user could ask Claude to create a spreadsheet chart or reformat a report, allowing the model to carry out a sequence of actions through the software rather than requiring the user to operate every control manually. The usefulness of this approach will depend on how reliably agents interpret instructions and how safely they perform edits.

The projects also arrive in a market where Microsoft 365 is sold through subscriptions. Microsoft 365 Personal costs $99.99 a year for a single user, while the family plan costs $129.99. A free application that opens and saves familiar file formats could appeal to people looking to avoid that recurring cost. Yet price is only one consideration: users may also depend on dependable file exchange, advanced features, support, and compatibility with colleagues or organizations using Microsoft’s products.

Free office software is not new. OpenOffice.org began after Sun Microsystems released the code for its StarOffice suite in October 2000. LibreOffice later split from OpenOffice.org in 2010. Those established alternatives were developed over years by large communities. By contrast, Thomas released the three Office-oriented applications less than two weeks after the Adobe clones, with an AI model assisting in the work. The speed of the release is striking, but it should not be mistaken for the long-term testing and maintenance that mature software typically requires.

Claude Opus 5.5, the model associated with ArtCraft, launched September 22 at $4 per million input tokens and $20 per million output tokens. Tokens are the text units that an AI model reads and generates, and they are also a common basis for billing AI services. On Terminal-Bench 4.0, a benchmark that evaluates whether agents can complete complex professional tasks in a command-line environment, Opus 5.5 scored 66.4%. Such a benchmark provides context about agent performance, but it does not by itself prove that the model can build fully reliable office software.

Thomas has previously made ambitious claims about the pace of development and later revised his pledge to match Adobe’s feature set within a month. That history makes it sensible to distinguish project ambition from finished capability. At the same time, interest has been substantial: WordCraft had collected more than 12,000 GitHub stars as of Wednesday. Stars indicate user interest or bookmarking on the platform, not necessarily active use, software quality, or readiness for business-critical work.

For potential users, the sensible approach is to evaluate each application against specific needs. Someone drafting simple documents may value a familiar interface and .docx support, while a company working with complex spreadsheets may need to test formulas, formatting, and file exchange before relying on GridCraft. Presentation creators should similarly assess animations, layouts, and PDF output in DeckCraft when it reaches an appropriate testing stage. The projects offer a compelling demonstration of AI-assisted software development, but their own readiness estimates and incomplete roadmaps underline the gap between a promising clone and a dependable replacement.

Key Insights Table