State of PDF in Ruby

by Thomas Leitner a.k.a. gettalong

Portable Document Format (PDF)

  • Originally developed by Adobe until including version 1.7
  • PDF 1.7 also released as ISO 32000-1 in 2008
  • PDF 2.0 (ISO 32000-2) released in 2017, updated in 2020
  • PDF 2.0 first version to be done by a standards group

PDF 2.0 Biggest Changes

  • Clarifications and corrections of the existing PDF 1.7 spec
  • Enhanced encryption
  • Better digital signatures
  • New annotation types
  • Tagged PDF enhancements
  • Deprecation of XFA Forms

PDF Libraries

  • For creating
  • For reading
  • For modifying

Creating PDFs

  • prawn
  • wicked_pdf
  • pdfkit
  • grover
  • hexapdf

Creating PDFs with Prawn

  • Current go-to pure Ruby library
  • Still actively developed, although at a slower pace
  • Support for OpenType fonts was recently added

Prawn Extension Gems

  • prawn-templates (using pages of another PDF as background)
  • prawn-table (for generating tables)
  • prawn-svg (using SVG as image format)
  • prawn-icon (for using icon fonts)
  • prawn-qrcode (rendering of QRCodes)

Gems using Prawn

  • invoice_printer
  • asciidoctor-pdf
  • And various others

Creating PDFs from HTML

  • wicked_pdf, pdfkit, grover
  • Use wkhtmltopdf or Puppeteer
  • Sometimes easier to design because it’s just HTML+CSS
  • But not fully in control over every aspect

Reading PDFs

  • pdf-reader
    • probably most well known
    • Can’t read all PDFs
    • Used by prawn-templates
  • origami
    • More fully-featured
    • No updates in the last two years
  • hexapdf

Modifying PDFs

  • combine_pdf
    • Only for merging, watermarking or stamping
    • Can’t handle all PDFs due to missing PDF features
  • origami
    • AcroForm
    • Digital signatures
    • … and more
  • hexapdf


  • Similar to prawn
  • Similar to pdf-reader
  • Similar to combine_pdf/origami
  • But also totally different

HexaPDF Features

  • Full-fledged PDF library
  • Strives to support most of the PDF specification
  • Fast and memory efficient
  • Low- and high-level interfaces
  • Accompanying command line tool

HexaPDF Status

  • Actively developed since 2014
  • 18 releases in the past year
  • Fully tested
  • AGPL licensed with commercial license available

HexPDF Compared to Prawn

  • Not yet on a par feature-wise
  • Different approach to page layouting

Raw Text Benchmark

raw text benchmark

Line Wrapping Benchmark

line_wrapping benchmark

HexaPDF Compared to combine_pdf/origami

  • combine_pdf/origami not optimized for performance
  • Narrow focus of combine_pdf, not a full PDF library
  • origami not actively developed

Optimization Benchmark

optimization benchmark

hexapdf Tool

Available commands:
    batch             Execute a single command on multiple files
    files             List or extract embedded files from a PDF file
    form              Show form fields and fill out a form
    help              Provide help for individual commands
    image2pdf         Convert one or more images into a PDF file
    images            List or extract images from a PDF file
    info              Show document information
    inspect           Dig into the internal structure of a PDF file
    merge             Merge multiple PDF files
    modify            Modify a PDF file
    optimize          Optimize the size of a PDF file
    split             Split a PDF file
    version           Show the version of the program
    watermark         Put one or more PDF pages onto another PDF

Recent HexaPDF Changes

  • Support for interactive forms (AcroForms)
  • Flattening of annotations and forms
  • Many enhancements for dealing with invalid files
  • Next feature release: Digital Signatures

Thank You!