Review: 7 PDF editing tools for iOS and Android

The PDF format has long been the standard for legal papers, forms and other documents -- as a result, iOS and Android phones and tablets tend to come with basic PDF readers. However, many users need to do more than just read PDFs -- they need to create and edit PDFs on the move. In this roundup, I look at what I consider the most useful PDF editors for mobile devices.

Good PDF editors let you take a photo of a paper form, fill out fields, sign it and send it off in just a few minutes. Annotation tools let you highlight key points and type or handwrite comments. More apps are starting to support styluses such as the iPad Pro's Pencil as well as those used by Microsoft's Surfaces and Samsung's Galaxy Note phablets. More sophisticated tools include the ability to rotate, move or delete pages; a few even let you combine two PDFs or split a few pages out into a new PDF when you don't want to share the whole document.

But choosing the best PDF editor can get confusing -- not only due to which features are included, but because of the way they're priced. More expensive apps usually, but don't always, include a full range of features; meanwhile, free apps may have ads that mean you can't see as much of your document as you'd like -- and in-app purchases for extra features can quickly add up.

Check out these seven PDF editors for Android and/or iOS to see which may work for you.

[ Further reading: Step-by-step guide to setting up dual boot on your PC or laptop ]

Adobe Acrobat Reader

Adobe Systems

While PDF is now an open standard, Adobe was its original developer and remains its caretaker. That makes the Adobe Acrobat Reader not only popular software that's usually bundled with your phone -- it's the reference implementation of PDF.

The latest version of Adobe's package has a simple, clean interface, but is saddled with a slightly confusing range of extras you unlock with cloud subscriptions. Those cloud subscriptions are the heart of Adobe's business model for PDFs, as it builds out the company's new Document Cloud service.

Options are tucked away in a neat menu that opens down the left side of the screen, and individual tools appear consistently at the bottom of the screen. Basic PDF annotation is free. The tools for drawing on the page, highlighting, underlining or striking through text, adding sticky notes with comments, adding new text fields or signing with your finger are very well designed for touch.

You can also fill out forms for free via the separate Fill & Sign app. Again, this is well designed and easy to use. You start with an existing PDF (if you have a Document Cloud subscription, you can take a photo of a paper form and use that). Then type into fields (including ones you can add to a photo of a form) or autofill with saved text like your address, and sign with your finger or stylus (you can save both your signature and initials).

You can open and save PDFs from a wide range of cloud services -- iCloud, Google Drive, Dropbox, Box and OneDrive -- for free, but if you subscribe to Adobe Acrobat Pro DC (and thus have access to Adobe's Document Cloud), you can automatically sync all PDFs you edit to all your devices (not to mention access extra editing tools).

Bottom line

Adobe Acrobat Reader is the original PDF tool, and it's still one of the best. If you only need to do basic reading and editing, it should cover most of what you need. Otherwise, you'll need to pay for Adobe Acrobat Pro DC, which is designed for businesses that need all the features, from editing PDF text seamlessly (including matching the font) to locking fields once a form is signed, exporting PDFs and creating PDF files from scratch.  

Foxit MobilePDF

Foxit Software

Foxit has long provided an alternative to Adobe's PDF tools, both for desktop and on the web. The latest version of its mobile app, Foxit MobilePDF, brings many of its core features to iOS and Android, with tools for easy editing and creation of PDF files.

The mobile versions of Foxit's tools have a compact user interface that's well suited to smaller devices, with quick access to key features. Many of the more useful features are individual in-app purchases (at 99 cents each), like the ability to create a new PDF or turn an image into a PDF. This starts to add up if you need access to different cloud services like Google Drive and Dropbox, as you have to buy those individually; you also have to buy them separately for an iPhone and iPad. Oddly, some services that require in-app purchases on iOS (like cloud integration) are free on Android.

Foxit's new ConnectedPDF service aims to build on the company's existing tools, using user accounts to link its various apps together with a document-centric personal home page that you can access from inside MobilePDF. That approach makes Foxit a lot more flexible than you might initially think -- for example, you can use Foxit's camera app to quickly make a PDF and then edit it in MobilePDF, before sharing it with colleagues. The transition between app and cloud is a little jarring, taking you without warning from native app to embedded browser view and back again; I'd have preferred a smoother experience.

Bottom line

The combination of trusted PDF tools with a cloud service makes a lot of sense, and Foxit is clearly attempting to compete with Adobe's new PDF services. However, the cloud aspects of Foxit's service are still a little bare bones and need to evolve to match the maturity of its various apps. It's clear there's a lot of promise here, but the web service needs to be optimized for mobile devices.

GoodReader

GoodWare

GoodReader excels as a pure PDF reader, especially for large documents like textbooks and software manuals. It renders pages quickly and clearly; making it easy to quickly upload a PDF edition of a book onto an iPad and then read it on the go -- a lot easier to use than a Kindle, and a better way of reading large PDFs than in Adobe's Acrobat Reader.

This isn't a tool that's focused on filling in forms or editing PDFs. Yes, it has basic editing functions, and you can annotate or sign pages, but that's more a way of adding your own notes to an existing document, the electronic equivalent of writing in the margins of a book, or when you want to review a document and share your thoughts with colleagues. While there are tools that can be used to, for example, type into forms, they don't integrate with modern PDF workflows. As you can't work with embedded scripts, you're left using PDFs as if they were paper forms, missing out on many modern PDF features.

GoodReader is designed to sync documents to a local file store, so you have everything with you, wherever you are. There's support for a lot of different sync endpoints, from cloud services to local drives on PCs and Macs. GoodReader's sync model does make working with cloud services a little harder; files need to be copied to your device before you can open them.

Connections don't need to be permanent, as you're able to use wireless connections to link to a device running GoodReader, so you don't have to connect to a network to transfer files.

Bottom line

PDF tools normally don't make good e-readers, but GoodReader is an exception to the rule. For times when you need to care about the original layout of the page -- for example, if you're proofreading a book and need to be aware of the original page order -- then using GoodReader on a large-screen phone makes sense, as it gives you a full page view rather than reflowing PDF content to fit mobile screens. However, if you a tool for all but the most basic editing, you may need to look elsewhere.

iAnnotate 4

Branchfire

iAnnotate 4 is a full-featured PDF editor that is now available for both the iPhone and the iPad -- and if you have an Apple Pencil you can use that for annotations while you scroll with your fingers. 

There's an excellent range of annotation tools -- in addition to the usual pen, highlighter, comments, shapes and arrows, strikethrough, underline, stamps and text boxes (which can include today's date), you can insert photos and sound clips. There's a really wide range of stamps, including grades (ideal for teachers marking essays) and signature lines, and you can make your own. If you want to choose your own pen colors, iAnnotate gives you a full color mixer, similar to those offered by Photoshop and other graphics software.

There are nice touches like an optional "wrist guard" that grays out the bottom of the screen and keeps it from accepting input. (Useful if you're using a stylus and resting your hand on the screen.) You can grab web pages and annotate them as PDFs; create new PDFs with graph paper or lined backgrounds; send only the pages of a PDF that you've annotated; and flatten annotations so no one can edit them later.

There are almost more features than the simple UI can fit in; it's hard to find tools in multiple toolboxes, and it can be cramped, even on the larger screen of an iPad. However, you can drag your favorite tools onto the app's toolbar.

The app works with the usual cloud storage services (including OneDrive for Business), but the thumbnail view it uses to display cloud files means you may not see full file names, which is awkward.

There are a few things I'd change. If you want to fill in a form you have to create all the fields as text boxes -- so if you want to save, say, your signature, you have to turn it into a stamp. Beyond that, hardly any of the annotation tools have an undo option; if you don't like an annotation, you have to accept and then delete it.

Bottom line

iAnnotate is a useful, full-featured tool, let down by an overly complex UI and a rather high price.