Extracting text from PDFs in C# [closed]

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Pretty simply, I need to rip text out of multiple PDFs (quite a lot actually) in order to analyse the contents before sticking it in an SQL database.

I've found some pretty sketchy free C# libraries that sort of work (the best one uses iTextSharp), but there are umpteen formatting errors and some characters are scrambled and alot of the time there are spaces (' ') EVERYWHERE - inside words, between every letter, huge blocks of them taking up several lines, it all seems a bit random.

Is there any easy way of doing this that I'm completely overlooking (quite likely!) or is it a bit of an arduous task that involves converting the extracted byte values into letters reliably?

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There may be some difficulty in doing this reliably. The problem is that PDF is a presentation format which attaches importance to good typography. Suppose you just wanted to output a single word: Tap.

A PDF rendering engine might output this as 2 separate calls, as shown in this pseudo-code:

moveto (x1, y); output ("T")
moveto (x2, y); output ("ap")

This would be done because the default kerning (inter-letter spacing) between the letters T and a might not be acceptable to the rendering engine, or it might be adding or removing some micro space between characters to get a fully justified line. What this finally results in is that the actual text fragments found in PDF are very often not full words, but pieces of them.

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Take a look at Tika on DotNet, available through Nuget: https://www.nuget.org/packages/TikaOnDotnet.TextExtractor/

This is a wrapper around the extremely good Tika java library, using IKVM. Very easy to use and handles a wide variety of file types other than PDF, including old and new office formats. It will auto-select the parser based on the file extension, so it's as easy as:

var text = new TextExtractor().Extract(file.FullName).Text;

Update: One caution with this solution is that development on IKVM has ended. I'm not sure what this will mean in the long run. http://weblog.ikvm.net/2017/04/21/TheEndOfIKVMNET.aspx

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In case you are processing PDF files with the purpose of importing data into a database then I suggest to consider ByteScout PDF Extractor SDK. Some useful functions included are

• table detection;
• text extraction as CSV, XML or formatted text (with the optional layout restoration);
• text search with support for regular expressions;
• low-level API to access text objects

DISCLAIMER: I'm affiliated with ByteScout

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You can try Toxy, a text/data extraction framework in .NET. It supports .NET standard 2.0. For detail, please visit https://github.com/nissl-lab/toxy

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You can try Docotic.Pdf library (disclaimer: I work for Bit Miracle) to extract text from PDF files. The library uses some heuristics to extract nice looking text without unwanted spaces between letters in words.

Please take a look at a sample that shows how to extract text from PDF.

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If you're looking for "free" alternative, check out PDF Clown. I personally have used iFilter based approach, and it seems to work fine in case you would need to support other file types easily. Sample code here.