A bibliometric and text-mining tool that turns PDFs into word co-occurrence networks compatible with VOSviewer.
🔗 Live demo: text-umber-delta.vercel.app
PDFWords lets you load one or more PDF files, extract the text locally (with nothing sent to a server), process the words and generate a JSON file in the format accepted by VOSviewer Online. With that file you can visualise word co-occurrence maps in seconds.
It is especially useful for researchers carrying out bibliometric analyses, systematic literature reviews and text-mining studies.
For a directed, controlled-vocabulary approach (you define the terms and the app counts them), see the companion tool PDFTerms.
- Upload of multiple PDFs by drag & drop or selection
- 100% local text extraction (no data sent anywhere)
- Generation of a word co-occurrence network in the VOSviewer JSON format
- Configurable parameters:
- Minimum occurrence frequency
- Minimum co-occurrence between terms
- Maximum number of words in the network
- Minimum character length per word
- Automatic stopwords in Portuguese and English
- Custom stopwords via the interface
- Export of the VOSviewer JSON
- Export of frequencies as CSV
- Direct opening in VOSviewer Online
- Responsive and accessible interface
- Go to text-umber-delta.vercel.app
- Drag your PDFs into the upload area (or click to select)
- Adjust the network parameters as needed
- Click Generate co-occurrence network
- Download the generated JSON
- Open app.vosviewer.com, click Open → VOSviewer JSON file and load the file
Note: scanned PDFs (image only) need OCR before processing.
| Technology | Use |
|---|---|
| HTML / CSS / JavaScript | Interface and application logic |
| PDF.js (v3.11) | Text extraction from PDFs |
| VOSviewer | Co-occurrence network visualisation |
| Vercel | Hosting and continuous deployment |
All processing happens in the user's browser. No file or data is sent to external servers.
Cunha, D. R. (2026). PDFWords: bibliometric text-mining for VOSviewer co-occurrence networks (v0.1.0) [Software]. Zenodo. https://doi.org/10.5281/zenodo.20708534
Darliane Ribeiro Cunha, PhD Researcher in sustainability governance, environmental analytics and the SDGs ORCID: 0000-0003-2548-1237
This project is free to use for academic and research purposes.