Quick answer: prefer a local browser workflow when the task does not genuinely require a server, and always verify important output.
A PDF page can contain text or only a picture
A digitally created PDF usually stores characters with positions and fonts. A text extractor can read those characters directly. A scanned PDF may contain only page images, even though the page visibly contains words.
If you cannot select a word in a normal PDF viewer, the document probably needs optical character recognition rather than ordinary text extraction.
Why extracted reading order can look wrong
PDF is designed to preserve visual placement, not necessarily semantic reading order. Multi-column pages, tables, headers, footers and individually positioned letters can be returned in an unexpected sequence.
Treat extraction as a starting point. Compare important passages with the original page before using the text in a publication or analysis.
When OCR is required
OCR analyzes pixels and predicts characters. It is more computationally expensive and can make mistakes with handwriting, low resolution, unusual fonts or mixed languages.
The current InYourTab.com text extractor does not claim to perform OCR. Convert pages to images only when that is useful for a separate, trusted OCR workflow.
Protect confidential documents
Local extraction keeps the source PDF in the tab, but copied text can still be sensitive. Store and share the result according to the same rules as the original document.
Password protection, digital signatures and access restrictions should be respected. Do not process a document unless you are authorized to use its contents.