Reading PDF document

You can use Spire.PDF for .NET to read PDF documents. It supports extracting text, tables, images, and reading form fields.

Simplest text extraction example:

using Spire.Pdf;
using Spire.Pdf.Texts;

PdfDocument pdf = new PdfDocument();
pdf.LoadFromFile("sample.pdf");

foreach (PdfPageBase page in pdf.Pages)
{
    PdfTextExtractor extractor = new PdfTextExtractor(page);

    // Create and configure the options
    PdfTextExtractOptions options = new PdfTextExtractOptions();
    options.IsExtractAllText = true; // Extract the entire page

    // Pass options into ExtractText
    Console.WriteLine(extractor.ExtractText(options));
}

pdf.Close();

You can use pdfpig package for this matter.

using System.Collections.Generic;
using System.Linq;
using UglyToad.PdfPig;
using UglyToad.PdfPig.Content;

public static class Program
{
    public static void Main()
    {
        using (PdfDocument document = PdfDocument.Open(@"C:\path\to\pdffile\file.pdf"))
        {
            foreach (Page page in document.GetPages())
            {
                IReadOnlyList letters = page.Letters;
                string example = string.Join(string.Empty, letters.Select(x => x.Value));

                IEnumerable words = page.GetWords();

                IEnumerable images = page.GetImages();
            }
        }
    }
}