LLM File Format Support
An AI model is only as intelligent as the data you give it. Before you invest in an AI solution, ask yourself: can it understand the file formats your business runs on every day?
The ability to accurately read a .docx proposal, extract data from a .pdf invoice, or parse a .xlsx financial report is not a minor technical detail—it is the core of a successful implementation. Choosing a model that struggles with your primary document types can lead to frustrating errors, inaccurate results, and a failed project.
This practical guide provides a clear comparison of how today's leading Large Language Models (LLMs)—ChatGPT, Claude, DeepSeek, and Gemini—handle the file formats that matter most, helping you make a more informed strategic choice.
Standard Business Documents: The Everyday Essentials
This category covers the bedrock of business communication: text documents, PDFs, and presentations.
- Simple Text & Word Documents (.txt, .docx): All major models handle plain text reliably, and all four now offer strong support for modern Word documents, including headings, lists, and basic tables. ChatGPT and Claude have improved significantly on complex layouts, while Gemini and DeepSeek remain strong on documents that mix text with tables or embedded images.
- PDFs (.pdf): This remains a key differentiator, but the gap has narrowed. All four models can extract text from simple PDFs, and ChatGPT, Claude, Gemini, and DeepSeek now all offer multimodal “vision” capabilities for reading scanned pages, charts, and images. Gemini and DeepSeek are still particularly strong on heavily visual PDFs, but recent updates mean ChatGPT and Claude handle more non‑standard layouts than before.
Business Takeaway: If your workflows rely heavily on complex PDFs (like scanned invoices, architectural plans, or graphical reports), prioritise models with robust “vision” support and strong PDF tooling around them. Gemini and DeepSeek remain very strong options here, but the latest versions of ChatGPT and Claude are now also viable for many complex PDF scenarios.
Structured Data: The Language of Your Numbers
The ability to natively understand structured data formats like spreadsheets and databases is crucial for any serious data analysis or business intelligence task.
- Spreadsheets (.csv, .xls, .xlsx): All four models can work well with .csv files and can interpret tabular data pasted or uploaded from spreadsheets. Gemini still offers strong native handling of complex, multi‑sheet Excel workbooks, but ChatGPT, Claude, and DeepSeek have all added better tooling and integrations for reading and manipulating .xlsx files, especially when combined with their ecosystem plugins or APIs.
- Data & Configuration Files (.json, .xml, .yaml): ChatGPT and Claude continue to excel at working with JSON, XML, and YAML, which is valuable for developers and API‑driven workflows. Gemini and DeepSeek have improved in this area and can reliably interpret common API responses and configuration files, although ChatGPT and Claude are still usually the first choice for deeply technical, developer‑focused tasks.
Business Takeaway: For AI projects involving financial analysis, sales forecasting, or business intelligence, you should consider both how well a model understands tables and how easily it integrates with your existing reporting tools. Gemini remains a strong option for complex Excel‑heavy workflows, while ChatGPT, Claude, and DeepSeek now offer more mature options for connecting to databases, BI tools, and APIs. ChatGPT and Claude are still particularly compelling where deep integration with other software and developer tooling is required.
Developer & Academic Formats
For technical documentation, software development, and academic research, specific formats are essential.
- Code & Markup (.md, .html): All four models show strong support for Markdown and HTML, which are fundamental for understanding software documentation and web content.
- Academic Formatting (.tex): ChatGPT and Claude excel at interpreting LaTeX, the standard for scientific and academic papers, making them invaluable tools for researchers and academics.
Business Takeaway: If your business operates in a technical or scientific field, the strong LaTeX support from ChatGPT and Claude can be a deciding factor.
At-a-Glance Comparison Table
✅ Full support (reads the file reliably in most business scenarios)
⚠️ Partial support (extracts text but may struggle with advanced formatting)
❌ No support
🔍 Can read metadata only
Format | ChatGPT | Claude | DeepSeek | Gemini |
Plain Text (.txt) | ✅ | ✅ | ✅ | ✅ |
Markdown (.md) | ✅ | ✅ | ✅ | ✅ |
Rich Text Format (.rtf) | ✅ | ✅ | ⚠️ | ⚠️ |
CSV (.csv) | ✅ | ✅ | ✅ | ✅ |
JSON (.json) | ✅ | ✅ | ✅ | ✅ |
XML (.xml) | ✅ | ✅ | ⚠️ | ✅ |
YAML (.yaml, .yml) | ✅ | ✅ | ✅ | ⚠️ |
HTML (.html) | ✅ | ✅ | ✅ | ✅ |
LaTeX (.tex) | ✅ | ✅ | ❌ | ❌ |
PDF (.pdf) | ⚠️ | ⚠️ | ✅ | ✅ |
Word Documents (.docx) | ⚠️ | ⚠️ | ✅ | ✅ |
Excel Spreadsheets (.xls, .xlsx) | ⚠️ | ⚠️ | ⚠️ | ✅ |
ZIP Files | 🔍 | 🔍 | ❌ | 🔍 |
Conclusion: Choose the AI That Speaks Your Company's Language
There is no one-size-fits-all answer. The "best" AI model is the one that is most fluent in the specific file formats your business relies on.
- Choose Gemini if your world revolves around complex PDFs and Excel spreadsheets, and you want strong native handling of visual documents and workbooks.
- Choose ChatGPT or Claude if you need to process highly technical or academic documents, work extensively with JSON / APIs, or integrate closely with existing software systems.
- Choose DeepSeek if you need a cost‑efficient, flexible base model with solid support for standard business document formats and are planning to build a custom solution around it.
Making the right choice from the outset prevents costly rework and ensures your AI investment delivers tangible results.
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With so many large language models (LLMs) available, selecting the right one depends on your specific needs. Whether you're coding, analysing documents, working within a team, or managing costs, each model offers unique strengths. Here's a quick guide to help you decide which LLM best fits your use case.
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