List of PDF software

This is a list of links to articles on software used to manage Portable Document Format (PDF) documents. The distinction between the various functions is not entirely clear-cut; for example, some viewers allow adding of annotations, signatures, etc. Some software allows redaction, removing content irreversibly for security. Extracting embedded text is a common feature, but other applications perform optical character recognition (OCR) to convert imaged text to machine-readable form, sometimes by using an external OCR module.

Terminology

Creators – to allow users to convert other file formats to PDF.
Viewers – to allow users to open, read and print PDF files.
Editors – to allow users to edit or otherwise modify PDF files.
Converters – to allow users to convert PDF files to other formats.

Multi-platform

Name	License	Platforms				Converts PDF to other format	Edits existing PDF	Description
Name	License	Linux	Mac	Windows	Other	Converts PDF to other format	Edits existing PDF	Description
Adobe Acrobat	Proprietary	No	Yes	Yes	Android, iOS, iPadOS and Online	Yes	Yes	View, create, manipulate, print and manage files in PDF.
Apache OpenOffice	GNU LGPLv3	Yes	Yes	Yes		Yes		Import from PDF (with restrictions) (after installing an extension), export as PDF including PDF/A.
Apache OpenOffice Draw	GNU LGPL	Yes	Yes	Yes			Yes	PDF import via software, or extensions.
Apache PDFBox	Apache License 2.0	Yes		Yes	Unix	Yes		Converts PDF to other file format (text, images, html).
Collabora Online	MPLv2.0	Yes	Yes	Yes	Android, iOS, iPadOS, ChromeOS and Online	Yes	Yes	Import from PDF, export as PDF 2.0, PDF/A-1b > PDF/A-4
Foxit Software	Proprietary	Yes	Yes	Yes	Android, iOS, iPadOS and Online	Yes	Yes	View, create, manipulate, print and manage files in PDF.
GIMP	GNU GPL	Yes	Yes	Yes		Yes		Converts PDF to raster images.
ImageMagick	ImageMagick License^[1]	Yes	Yes	Yes		Yes		Converts PDF to raster images and vice versa.
Inkscape	GNU GPL	Yes	Yes	Yes		Yes	Yes	Import-/Export- from multipage PDF to multipage PDF or (Vector-)graphics.^[2]
Karbon	GNU GPL/LGPL	Yes	Yes	No	BSD, Solaris/Illumos		Yes	Import PDF with multiple pages as layouts, export as a one-page PDF. All standard vector graphics editor features.
LibreOffice	GNU LGPLv3 / MPLv2.0	Yes	Yes	Yes		Yes		Import from PDF (extension included by default), export as PDF 2.0, PDF/A-1b > PDF/A-4
LibreOffice Draw	GNU LGPLv3 / MPLv2.0	Yes	Yes	Yes		Yes	Yes	PDF viewing and limited editing.
Mobipocket Creator	Proprietary			Yes		Yes		Import from PDF and create HTML and MOBI output.
Serif PagePlus	Proprietary			Yes			Yes	Desktop publishing (DTP) application allows opening and editing of PDF documents; Allows compatible saving as PDF 1.3, 1.4, 1.5 and 1.7 and supports also PDF/X1, PDF/X1a and PDF/X-3.
pdf-parser	Public Domain				Python script	Yes		Extraction and analysis tool, handles corrupt and malicious PDF documents.
PDFedit	GNU GPL	Yes		Yes	BSD		Yes	Software to view or edit the internal structures of PDF documents, and merge them.
Pdftk	GNU GPL	Yes	Yes	Yes	FreeBSD, Solaris		Yes	Command-line tools to edit and convert documents; supports filling of PDF forms with FDF/XFDF data. GUI front-end exists (see PDFChain).
PDFsam Basic	AGPLv3 for version 3, GPLv2 for previous versions 2.x	Yes	Yes	Yes				Desktop application to split, merge, extract pages, rotate and mix PDF documents.
PDF Studio	Proprietary	Yes	Yes	Yes			Yes	Full feature PDF editor.
Poppler-utils	GNU GPL	Yes		Yes	Unix	Yes		Converts PDF to other file format (text, images, html).
pstoedit	GNU GPL	Yes		Yes	Unix	Yes		Converts PostScript to (other) vector graphics file format.
QPDF	Apache License 2.0	Yes		Yes		Yes		Structural, content-preserving transformations from PDF to PDF.
Scribus	GNU GPL	Yes	Yes	Yes	Unix, GNU/Hurd, Haiku, OS/2	Yes		Export PDF and many other formats, multi-pages and multi-layers. Supports JS forms Cannot edit PDF Files.^[3]
Smallpdf Desktop	Proprietary		Yes	Yes		Yes	Yes	Supports merging, splitting, and extracting pages from PDFs. Also rotating, deleting and reordering pages. Converts PDF to Word, Excel, PowerPoint, raster images.
Soda PDF	Proprietary			Yes		Yes	Yes	Modular PDF software.
Solid Converter PDF	Proprietary		Yes	Yes		Yes		PDF to Word, Excel, HTML and Text; supports passwords, text editing, and batch conversion.
SWFTools	GNU GPL	Yes	Yes	Yes		Yes		SWF conversion and manipulation suite containing a standalone PDF to SWF converter along with a Python gfx API (requires Xpdf).

Development libraries

These are used by software developers to add and create PDF features.

Name	License	Description
Apache PDFBox	Apache License	Java developer library for creating, view, extract, print PDF files.
BIRT Project	EPL 2.0	Open-source Java based Business Intelligence and Reporting Tools (BIRT) that can create output into PDF, HTML, Web Viewer, Microsoft XLS, XLSX, Doc, Docx, PPT, PPTX, ODT, ODS, ODP, Postscript, comma-separated values and XML files and can be integrated into websites or extended for individual formats and database output.
Formatting Objects Processor	Apache License	Open-source print formatter driven by XSL Formatting Objects and an output independent formatter; main output target is PDF.
iText	Proprietary/AGPL	Library to create and manipulate PDF, RTF, HTML files in Java, C#, and other .NET languages.
JasperReports	GNU LGPL	Open-source Java reporting tool that can write to screen, printer, or into PDF, HTML, Microsoft Excel, RTF, ODT, comma-separated values and XML files.
libHaru	ZLIB/LIBPNG	Open-source, cross-platform C library to generate PDF files.
OpenPDF	GNU LGPLv3 / MPLv2.0	Open source library to create and manipulate PDF files in Java. Fork of an older version of iText, but with the original LGPL / MPL license.
PDFsharp	MIT	C# developer library to create, extract, edit PDF files.
Poppler	GNU GPL	Open-source multi-backend C++ library derived from Xpdf; no bundled viewer; incl. pdftohtml converter.
TCPDF	GNU LGPL	Open-source PHP library to create PDF files.

Creators

These create files in their native formats, but then allow users to export them to PDF formats.

Name	License	Platforms	Description
Adobe Acrobat	Proprietary	Windows, macOS	Desktop PDF authoring suite.
Adobe Illustrator	Proprietary	Windows, macOS	Illustrator can save as PDF, and can recognize and edit text and graphics.
Collabora Online	MPLv2.0	Windows, macOS, Linux, Android, iOS, iPadOS, ChromeOS and Online	All Collabora Online applications allow PDF export; supports also PDF/A-4b; since many import formats are supported (e.g., docx, xlsx, pptx, rtf, doc, xls, ppt, odt, others) conversion is also possible.
FineReader	Proprietary	Windows, macOS, Linux	OCR tool; can save as PDF, and recognize text from PDF.
Ghostscript	Proprietary/AGPL	Linux, Windows, macOS, UNIX	Viewer, creator, converter; supports also PDF/X-3; used by PdfCreator (until v1.7.3 then .NET Framework 4 since v2.0.0), WinPdf, BullzipPdf, CutePDF freeware version and others.
Microsoft Office	Proprietary	Windows, macOS	All Microsoft Office products from 2007 version allow users to Save as PDF.
Apache OpenOffice	GNU LGPL	Linux, Windows, macOS	All OpenOffice.org applications allow PDF export; supports also PDFA; since many import formats are supported (e.g., doc, docx, rtf, xls, ppt) conversion is also possible.
LibreOffice	GNU LGPLv3 / MPLv2.0	Linux, Windows, macOS	All LibreOffice applications allow PDF export; supports also PDF/A-4b; since many import formats are supported (e.g., docx, xlsx, pptx, rtf, doc, xls, ppt, odt, others) conversion is also possible.
Serif PagePlus	Proprietary	Windows	Desktop publishing (DTP) application; Allows compatible saving as PDF 1.3, 1.4, 1.5 and 1.7 and supports also PDF/X-1, PDF/X-1a and PDF/X-3.
PageStream	Proprietary	Windows, Linux, macOS, Amiga	Cross-platform desktop publishing application to open, edit, export.
Prince	Proprietary	Linux, macOS, Windows, Solaris,	Converts HTML, XML, SVG, and MathML to PDF by way of CSS.
Scribus	GNU GPL	Linux/UNIX, macOS, OS/2 Warp 4/eComStation and Windows desktops	Cross-platform desktop publishing (DTP) application; supports also PDF/X-3.
LaTeX, TeX	LaTeX Project Public License, Permissive	Windows, macOS, Linux	Mark-up language and tools to write technical reports, books, magazines, almost any publication type.
LuaTeX	GNU GPL	Windows, macOS, Linux	TeX typesetting system that creates PDF documents.
pdfTeX	GNU GPL	Windows, macOS, Linux	TeX typesetting system that creates PDF documents.
XeTeX	MIT	Windows, macOS, Linux	TeX typesetting system that creates PDF documents.

Viewers

These allow users to view (not edit or modify) any existing PDF file.

Name	License	Description
Adobe Reader	Proprietary, freeware	Adobe's PDF reader
Evince	GNU GPL	Universal viewer for GNOME.
Foxit Reader	Proprietary, adware	PDF Viewer / Reader for Desktop computer and Mobile Devices. Allows users to add many elements to PDFs (e.g. arrowed comment boxes, text boxes, links, bookmarks, and images).
Ghostview	Aladdin Free Public License	A graphical interface for Ghostscript.
Javelin PDF Reader	Proprietary, freeware	A full functionality PDF reader with support for DRM using encoded and encrypted PDF files in Drumlin's DRMX and DRMZ formats.
Chromium	BSD	Browser includes PDF viewer functionality. Google Chrome (which is based on Chromium) uses the same PDF viewer. Microsoft Edge licenses several Adobe features and branding within its PDF viewer.
MuPDF	Proprietary/AGPL	PDF conversion and rendering with anti-aliased graphics.
Okular	GNU GPL	Universal viewer by KDE.
PDF.js	Apache License 2.0	A JavaScript library to convert PDF files into HTML5, usable as a web-based viewer that can be included in web browsers. Firefox has PDF.js built-in by default.
Qiqqa	Proprietary, freeware	View PDFs in a variety of zoom layouts, annotate, tag, search, cross-reference.
Utopia Documents	GNU GPL v3	Semantic scientific PDF reader (optimized for life sciences and medicine), allows public comments on PDFs, generates on-the-fly link-outs to scientific databases and resources when used while online.
XpdfReader	Proprietary, freeware	Multi-platform viewer based on Xpdf library; source and binaries available for Linux, Windows and Macintosh.

AmigaOS

Converters

Antiword: A free Microsoft Office Word reader for various operating systems; converts binary files from Word 2, 6, 7, 97, 2000, 2002 and 2003 to plain text or PostScript; available for AmigaOS 4, MorphOS, AROS x86
dvipdfm: a DVI to PDF translator with zlib support

Viewers

XpdfReader: a multi-platform viewer for PDF files, Amiga version uses X11 engine Cygnix.

Linux and Unix

Converters

Collabora Online can be used as a web application, a command line tool, or a Java/Python library. Supported formats include OpenDocument, PDF, HTML, Microsoft Office formats (DOC/DOCX/RTF, XLS/XLSX, PPT/PPTX) and others.

Creators, editors and viewers

Name	License	Functions						Description
Name	License	View	Annotate	Edit	Create	Convert	Library	Description
Okular	GNU GPL	Yes	Yes					KDE desktop environment; replaces KPDF. Supports a range of annotation types. Annotations are stored separately from the unmodified PDF file, or (since version 0.15 with Poppler 0.20) can be saved in the document as standard PDF annotations.
Evince	GNU GPL	Yes	Yes					Default PDF and file viewer for GNOME; replaces GPdf. Supports addition and removal (since v3.14), of basic text note annotations.
CUPS	Apache License 2.0	No	No	No		Yes		Printing system can render any document to a PDF file, thus any Linux program with print capability can produce PDF files
Pdftk	GPLv2	No		Yes		Yes		Command-line tools to merge, split, en-/decrypt, watermark/stamp and manipulate PDF document files. Front end to an older version of the iText library.
poppler	GNU GPL					Yes	Yes	Utility library for rendering Portable Document Format (PDF) documents. poppler-utils includes command-line tools to extract images from a PDF (pdfimages) and convert a PDF to other formats (pdftohtml, pdftotext, pdftoppm).
ps2pdf	GNU AGPL					Yes		Part of Ghostscript; converts a PostScript file to a PDF.
SWFTools	GNU GPL					Yes		pdf2swf component converts PDF to SWF.
Scribus	GNU GPL				Yes			Open source program for page layout.
XpdfReader	GNU GPL	Yes					Yes	Based on Xpdf open source multi-backend library for viewing and manipulating PDF files.
PDF Studio	Proprietary	Yes		Yes				Software for viewing and editing PDF documents
Inkscape	GNU GPL			Yes				Technically not a PDF editor, but can be used as such page by page
Adobe Reader	Proprietary freeware	Yes						Extant versions are obsolete, Adobe has stopped support for Linux.
Firefox	MPL	Yes						Includes a PDF viewer
Google Chrome	Proprietary freeware	Yes						Includes a PDF viewer
MuPDF	Proprietary/AGPL	Yes	Yes				Yes	Lightweight document viewer.
Zathura	zlib License	Yes						Lightweight document viewer with vim-like keybindings.

macOS

Converters

deskUNPDF for Mac: proprietary application from Docudesk to convert PDF files to Microsoft Office, LibreOffice, image, and data file formats

Creators

macOS: Creates PDF documents natively via print dialog

Editors

Adobe Acrobat: Proprietary PDF authoring suite
PDF Expert: Proprietary PDF viewer and editor.
PDF Studio: Proprietary software to view and edit PDF documents.
PDF Signer: Proprietary; fills forms and embeds image signatures in PDF documents

Viewers

Safari: This bundled web browser has built-in support for reading PDF documents.
Firefox: Includes a PDF viewer
Google Chrome: Includes a PDF viewer
Preview: macOS's default PDF viewer; in Mac OS X v10.5 and later, it also can rotate, reorder, annotate, insert, and delete pages. It can also merge files, create new files from existing files, and move pages between files
Adobe Reader: Adobe Systems's reader which is also available for Macintosh; Safari plug-in available
Skim, an open-source (BSD licence) PDF reader and note-taker for macOS
Foxit Reader: Proprietary, freeware. Allows users to add elements to PDFs (e.g. arrowed comment boxes, text boxes, links, bookmarks, and images)

Microsoft Windows

Converters

Adobe Acrobat: Can convert files into PDF or convert PDF files into other formats
ABBYY FineReader: Commercial PDF converter which converts PDF into Word (.doc), Excel (.xls), PowerPoint (ppt), and more
deskUNPDF: PDF converter to convert PDFs to Word (.doc, docx), Excel (.xls), (.csv), (.txt), more
GSview: File:Convert menu item converts any sequence of PDF pages to a sequence of images in many formats from bit to tiffpack with resolutions from 72 to 204 × 98 (open source software)
Google Chrome: convert HTML to PDF using Print > Save as PDF.
gDoc Fusion: Proprietary, shareware; PDF views, edits, converts documents into PDF, XPS or Microsoft Word document; after 30 days a watermark is placed on documents in shareware version
OmniPage: Converts to and from PDF and other formats with many options.
Nitro PDF Reader: (Freeware) Extracts Images in original resolution.
PDF-XChange: PDF Tools and PDF-XChange print driver allow conversion from many formats to PDF. A "lite" version of the print driver is free for non-commercial (home and academic) but places a watermark on documents
Qiqqa: Converts Microsoft Word document and Web Pages to PDF.
SWFTools: 'pdf2swf component converts PDF to SWF – command line with GUI wrapper
poppler-utils a collection of tools builds on poppler to convert PDF contents to everything
GraphicsMagick: Can convert PDF to PNG or other formats.

Creators

Name	License	Freeware version	Description
Bullzip PDF Printer	Proprietary	Yes	Virtual printer, requires Ghostscript and PDFPowerTool.
CC PDF Converter	GNU GPL	—	Virtual Printer. Creates a PDF with embedded Creative Commons license from any software. Bundled with optional proprietary Razoss adware and browser tools.
CutePDF	Proprietary	Yes	Virtual printer, also with proprietary PDF editor. Attempts to install the Ask Toolbar as well as Hotspot Shield. Can be avoided by using the /no3d command-line switch. Includes OpenCandy adware.
deskPDF	Proprietary	No	Available for both client and terminal servers.
doPDF	Proprietary	Yes	Virtual printer. It doesn't use Ghostscript. Includes adware.
eCopy PaperWorks / eCopy PDF Pro Office^[4]	Proprietary	No	Nuance product
Foxit PhantomPDF	Proprietary	No
Foxit Reader PDF Printer	Proprietary	Yes	Virtual printer that comes with Foxit Reader.
gDoc Creator	Proprietary, shareware	No	Enterprise-level creator to create, review, edit, share or archive PDF and XPS documents. After 30 days shareware version places a watermark on documents.
HelpNDoc	Proprietary	Yes	Manual and documentation authoring tool with native PDF export. Free for personal use.
Mathcad	Proprietary	No	Mathcad worksheets can be saved as PDF files. Save as PDF only available in paid version.
Mountains	Proprietary	No	Image analysis and desk top publishing software dedicated to microscope users, and distributed under different brands by most microscope manufacturers. The pages produced can be saved into proprietary format, RTF and PDF.
Nitro PDF Reader	Proprietary	Yes	As with Adobe Acrobat, Nitro PDF Pro's reader is free; but unlike Adobe's free reader, Nitro's free reader allows PDF creation (via a virtual printer driver, or by specifying a filename in the reader's interface, or by drag-'n-drop of a file to Nitro PDF Reader's Windows desktop icon); Ghostscript not needed.
PagePlus	Proprietary	No	Desktop publishing suite with PDF viewing, editing and creation features
PaperPort	Proprietary	No	Desktop publishing suite with PDF viewing, editing and creation features
PDFCreator	GNU GPL/Proprietary	Yes	Virtual printer for Windows using a custom license called FairPlay. Used Ghostscript GPL until v1.7.3. Now uses .NET Framework 4. Includes adware.
PDF24 Creator	Proprietary	Yes	A PDF creator and virtual PDF printer for Microsoft Windows
PDF-XChange	Proprietary	Yes	PDF Tools allows creation of PDFs from many types of source input (images, scans, etc.). The PDF-XChange print driver allows printing directly to a PDF. A "lite" version of the print driver is free for non-commercial (home and academic) use.
PrimoPDF	Proprietary	Yes	Virtual printer, for Microsoft .NET Framework and uses Ghostscript and RedMon. Connects with www.primopdf.com. Includes Open Candy adware.
Solid PDF Creator	Proprietary	No
Universal Document Converter	Proprietary	No	Virtual printer. It doesn't use Ghostscript.
Xara Photo & Graphic Designer	Proprietary	No	Graphic design software with PDF creation plus import, viewing and limited editing

Editors

Name	License	Description
Adobe Acrobat	Proprietary	Adobe Systems's proprietary desktop PDF authoring suite; includes a virtual printer.
Adobe Photoshop	Proprietary	Adobe Systems's Graphic Design software and image editor.
Bluebeam Revu	Proprietary	A commercial PDF editor, markup and collaboration product aimed at engineering and architectural markets.
Foxit Reader	Freeware	Highlight text, draw lines, measure distances of PDF documents.
Foxit PDF Editor Suite	Free trial	Integrated PDF Editing and eSign anywhere. Optionally, ChatGPT+
gDoc Fusion	Proprietary/Shareware	desktop product to create, review, edit, share or archive PDF and XPS documents. After 30 days a watermark is placed on documents in shareware version.
LibreOffice	Free (Mozilla Public License)	an Office suite; allows to export (and import, with accuracy limitations) PDF files.
Microsoft Word 2013	Proprietary	Desktop software. The 2013 edition of Office allows PDF files to be converted into a format that can be edited.
Nitro PDF Reader	Trialware	Text highlighting, draw lines and measure distances in PDF files.
Nitro PDF Pro	Proprietary	a proprietary commercial PDF creator/editor with an interface styled after Microsoft Office; replicates most or all features of the Adobe Acrobat full commercial version; offers a separate freeware reader (which also supports PDF creation, annotation, collaboration and signing); Ghostscript not additionally needed.
PDF Studio	Proprietary	Proprietary software for viewing and editing PDF documents.
pdftk	GNU GPL/Proprietary	command-line tools to manipulate, edit and convert documents; supports filling of PDF forms with FDF/XFDF data.
PDF-XChange Viewer	Freeware	Freeware PDF reader, tagger, editor (simple editions) and converter (free for non-commercial uses). Allows edit of text, draw lines, highlighting of Text, measuring distance.
Solid PDF Tools	Proprietary	Convert PDFs into editable documents and create PDFs from a variety of file sources.

Viewers

ABBYY FineReader PDF Viewer
Adobe Reader: Adobe's PDF reader is free for personal use.
Evince: a free (GPL), open source PDF reader. Part of the GNOME desktop environment. A Windows port was available from version 2.28 to version 2.32.
Foxit Reader: Proprietary/freeware PDF reader, supports FDF import/export, saving filled forms; other extended functionality available via purchasable plugins.
gDoc Fusion: Proprietary/shareware to view PDF, XPS, Microsoft Word document, Microsoft Excel spreadsheet, Microsoft PowerPoint presentation or image files, included in the evaluation version of the product. Shareware version places a watermark on documents after 30-day eval.
Google Chrome: Includes a PDF viewer.
GSview: Open source software and Ghostscript's viewer for Windows.
Microsoft Edge: Includes a PDF viewer.
Microsoft Reader: A discontinued PDF viewer in Windows 8.1.
Mozilla Firefox: Includes a PDF viewer.
MuPDF: Free lightweight document viewer.
Nitro PDF Reader: Freeware (though proprietary) PDF reader and creator. Supports three methods (specifying the file within the reader's interface, or dragging-'n-dropping a file onto the reader's Windows desktop icon, or "printing" to a virtual printer driver) of PDF creation (Ghostscript not additionally needed), saving filled forms (AcroForms), text typewriter, markup/collaboration, and stamp signature (document signing).
PDF-XChange Viewer: Freeware viewer with free OCR, supports FDF/XFDF import/export, saving filled forms, extended markup and export to image capabilities.
Qiqqa: Freeware PDF reader, indexer, tagger and annotator. Supports OCR and export of PDF text and images.
Sumatra PDF: A free (GPL), open source PDF reader based on MuPDF. It also supports DjVu, XPS, CHM, Comic Book (CBR, CBT, CBZ and CB7Z) and eBook (EPUB, FB2, FB2Z, PBD, MOBI, PBR, TCR & ZFB2), TXT and image file formats (.tga, .gif, .jpg, .j2k, .png, .webp, .tiff). Supports automatic .pdfsync & .synctex reloading of PDF files so is well favoured as a LaTeX / pdfTeX viewer with forward - inverse synchronization. Using Ghost script it supports PostScript (.ps, .eps) files.^[5]
STDU Viewer: A freeware for non-commercial usage PDF reader. It also supports DjVu, Comic Book Archive (CBR or CBZ), XPS, TIFF, TXT and image file formats.

Mobile

Name	License	Platform			Functions		Description
Name	License	Android	iOS	Other	View	Annotate	Description
Amazon Kindle app	Freeware	Yes	Yes	BlackBerry OS, webOS, Windows Phone	Yes	?
Collabora Online	MPLv2.0	Yes	Yes	ChromeOS and iPadOS. Also Windows, macOS, Linux and Online	Yes	Yes
Evince	GNU GPL	?	?	Maemo	Yes	?
Foxit PDF Editor	?	Yes	Yes		Yes	Yes
Google Drive app	Freeware	Yes	Yes		Yes	Yes
Apple Books	Proprietary	No	Yes		Yes	Yes^[6]
MuPDF	GNU AGPL	Yes	Yes		Yes	No	Lightweight document viewer
Qiqqa	Proprietary	Yes	?		Yes	Yes

Web-based

Creators

Collabora Online

Converters

Collabora Online supported formats include OpenDocument, PDF, HTML, Microsoft Office formats (DOC/DOCX/RTF, XLS/XLSX, PPT/PPTX) and others.
Zamzar: Online file converter
Smallpdf: Offers free (trial) online PDF conversion (PDF to other formats and vice versa)

Editors

PDFescape: an advertising and fee supported web service to view, create forms, fill out forms, and edit PDF documents from a web browser (requires JavaScript to be enabled)
PDFVue: a free web application that allows the user to view PDFs, comment and fill PDF forms from a web browser. Generates a watermark.
Smallpdf: Free (trial) web-based PDF software for editing, signing, compressing, merging, splitting, rotating, unlocking and protecting PDF files.

Viewers

A.nnotate: a web service which views PDF documents as HTML in the browser, with annotation features.
Docstoc: a web service which allows viewing PDF documents online.
Issuu: a web service which allows viewing PDF documents online.
Google Docs: a web service which views PDF documents as PNG images in the browser.
Scribd: a web service which renders PDF documents as HTML5 in the browser.
PDF.js: A Javascript-based library, with viewer, and browser extension.
PDFTron Systems: WebViewer. A free JavaScript viewer and annotator for self-hosting of web optimized PDFs.