Bibliometric analysis
PDFs to a word
co-occurrence network in VOSviewer
Upload your PDFs, extract the text, generate a JSON word co-occurrence network file and open it directly in VOSviewer Online.
1 — Upload PDFs
Drag PDFs here
or click to select — multiple files supported
2 — Network parameters
Minimum number of occurrences of a word
Minimum link strength between two terms
Most frequent terms to include in the network
Minimum number of characters per word
Type and press Enter, or paste separated by comma, semicolon or space
How to use
Upload the PDFs
Drag or select one or more PDFs. The text is extracted locally, with nothing sent to a server.
Adjust the parameters
Set the minimum frequency, minimum co-occurrence and maximum number of terms to control the size of the network.
Open in VOSviewer
Download the generated JSON and drag it into VOSviewer Online. The co-occurrence map will be displayed immediately.
Frequently asked questions
What is a co-occurrence network?
It is a network where each node represents a word and the links indicate that two words appear together in the same sentence. The more often they co-occur, the stronger the link. This is a classic analysis in bibliometrics and text mining.
How do I use the JSON in VOSviewer Online?
Download the generated JSON file, go to app.vosviewer.com, click "Open" in the top right, select "VOSviewer JSON file" and load the file.
Do scanned PDFs work?
Not directly. PDFs made up of images only need OCR first. The tool extracts text only from PDFs with a text layer (born-digital or with OCR already applied).
Which stopwords are removed?
Function words in Portuguese (de, a, que, para, com, etc.) and English (the, and, for, of, in, etc.) are removed automatically. This ensures that only terms with semantic content appear in the network.
The network produced no links — what now?
Try reducing the minimum frequency and minimum co-occurrence parameters. For short texts, values of 1 or 2 are usually enough. Increasing the maximum number of words also helps.