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PDFs are a monster to edit, but these 4 free apps make it easy peasy

Whether you're on an iPhone, Android phone, Mac or PC, I found free and easy ways to add text, sign documents and fill out forms.

Sending PDF files is pretty straightforward, but editing one can be a hassle, especially on your phone's relatively small screen. Maybe you just need to sign a document or fill out a form. Luckily we found easy and fast ways to edit a PDF file on an iPhone ($999 at Amazon) and Android phone, as well as on a Mac and PC. I'll walk you through basics like adding text, signing documents, adding annotations and filling out forms. And the best part is that all of the apps and software I recommend here are free.

I should note that none of these free apps allow you to make changes to existing text. If you're looking for paid apps that allow you to interact and adjust existing text, we are working on a roundup of our favorites. Also, if you'd like to follow along or see an overview of using all the apps in this story, check out out the video at the top of the story.

Basic PDF edits on a Mac

Every Mac comes with a program called Preview from Apple. You can use it to view and edit photos and PDF files. 

To start, simply double-click on your PDF file and it should automatically open in Preview. If for some reason this doesn't happen, open your Applications folder and then open Preview. It's the icon with a postcard of the ocean and a small magnifying glass on the corner. From there, you'll be greeted with a window asking you to select the file you want and when you're ready, click the blue Open button and you're back in the game. 

To access the toolbar, click the Markup tool on the top right side next to the search field. The icon is a pencil tip inside a circle. Click the Text tool -- it's the icon of a letter T inside a square -- and a text box will appear in the middle of your document. You can move the box anywhere on the page. 

To change the appearance of the text, tap the Text Style tool -- it's the icon with the italicized A. If you need to resize the text box, click on either of the blue dots. This will allow you to make the text field wider or more narrow by dragging them left or right.

There are also tools for drawing and sketching. The Draw tool lets you draw pretty much whatever you want with your cursor while the Sketch tool turns the objects you draw into shapes with a customizable fill and border. If you are just drawing a line or squiggle, you can change the color and thickness with the Shape Style tool -- the stacked parallel lines -- or Border tool -- the small square inside of a large square. If you're not feeling particularly artistic, you can also add premade shapes.

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Preview gives you a couple of ways to add and save a copy of your signature.

Apple

Perhaps my favorite tool is the ability to add a signature. Click on the arrow next to the Sign tool -- the cursive letter J -- and click the button Create Signature. You have to option to use your trackpad to sign your signature with your finger or scan it in with your Mac's built-in camera.

To use the trackpad, click the Trackpad tab then hit the Click Here To Begin button then once you're done signing press any key. If you like your signature, hit Done. The other way to create a signature is to sign your name on a white piece of paper and scan it. Instead of the Trackpad tab, choose the Camera tab. Place the piece of paper in front of the camera and line up your signature on the black line. After a moment, your signature will appear on screen in the camera preview. If you like it, hit Done.

To add one of your stored signatures, you just click on the one you want from the Sign menu. Then drag, resize and reposition it wherever your signature needs to go.

Finally to save any edits, simply hit Save. You can also export your changes an create a new PDF file.

Mark Up mode on the iPhone

Just like the Mac, you don't need a special app for basic edits on an iPhone. Instead of Preview, there's Mark Up mode. Whether you want to edit a PDF inside an email message or a file that's been saved in the Books app, tap on the Mark Up mode icon -- circle with a pencil tip in it -- to start. It's actually the same tools that pop up on your screen after you take a screenshot.

Across the bottom of the screen, there are different tools: a highlighter, pen, pencil and eraser. You can also tap on the plus sign on the right to add text boxes, shapes, a magnifier and even signatures.

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Mark Up mode is built right into iOS and allows for fast and easy edits of photos and PDF files.

Apple

If you have a signature saved in Preview on your Mac, your iCloud account will automatically sync it to Mark Up mode on your iPhone. To add a new one directly to your phone, tap Add or Remove Signature, then tap the plus sign on the top left of your screen. Use your finger to sign on the line and hit Done to save.

As you add edits to your PDF file, you can use the left and right undo arrows at the top to move forward or backward sequentially through your additions. But there's also an eraser tool that can be used to remove any unwanted drawings, sketches or highlights you made no matter the order you made them.

When you're done with edits, you can reply via an email message with your updated PDF or if you're inside Books, you can AirDrop it, email it or print it via the iOS share menu.

Adobe Fill & Sign on Android

Sadly there isn't a system-wide PDF editing tool built into the Android operating system, but luckily there is what seems to be an endless list of apps for editing PDF files in the Google Play Store. For basics, especially forms, I like Adobe Fill and Sign which is free on the Play Store.

To start, open Adobe Fill and Sign and choose your PDF file. The first time you open the app, you'll have the option to set the app to open by default anytime you open a PDF file. Once your file is open, tap anywhere on the screen add a text box. Once you've entered text, you can move the box around by tapping and dragging it. You can resize it using large and small letter As along the top bar of the text box.

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Adobe Fill & Sign is a free app for Android phones that lets you edit PDF files and especially deft at handling forms.

Adobe

Adding signatures and initials are easy. Adobe Fill & Sign limits you to one signature and one set of initials. The first time you tap on the tool a signature line will appear across the screen. Use your finger to sign your signature or initials. If you ever want to change your saved signatures or initials, just tap the X to the right side of the tool.

Your signature or initials will appear on your document in a resizable box that can also be dragged and repositioned. There is a small blue circle with white left and right arrows on the right side of the box. Tap and slide the circle either left or right to make it larger or smaller.

Adobe Fill & Sign also has a profile that you can store information like your address and email to populate forms. When you need to add any of this information to a PDF form, just tap on the field you want to populate and tap on the information saved in the same field in your profile. 

Throughout your editing, Adobe Fill & Sign saves as you go. When you're done, you can email your PDF file, save it to Google Drive or other apps via Android's share menu.

Adobe Acrobat Reader DC on PC

If you are on a PC, I recommend downloading Adobe Acrobat Reader DC. It's a free scaled-down version of Adobe Acrobat Pro DC. Reader DC has plenty of powerful tools for basic edits and if you're in an environment with a mix of PCs and Macs, there is also a Mac version.

Open Reader and choose the file you want to edit. There is a Tools tab that lets you select different toolsets depending on the edits you want to make. For example, one of the toolsets is Adobe Fill & Sign.

From the tool bar, you can add text boxes, signatures, initials, shapes and checkboxes. It works very similar to the way Preview does. 

One of my favorite tools in Acrobat Reader is the rubber stamp tool. Click on the Tools tab, and open the Stamp toolset. The toolbar will now have a Stamp tool and a Stamp tool palette which includes a number of different types of stamps you can choose from, like "Approved," "Sign Here," and "Confidential," among others.

When you're done with your PDF edits, you can save them or export them into a new PDF file or a different file format like a Word Doc.

Now that you have several ways to edit a PDF file, take a look at our video on how to make your own GIF below.

Now playing: Watch this: Try iOS 11's Notes app as a document scanner
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Originally published Aug. 12.

Update Aug. 18: Clarifies cost of Adobe Acrobat Reader DC

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