PDFs are hard to edit, but these four free apps make it easy

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

Sending a PDF file is easy, but editing one can be a hassle, especially with the relatively small screen on your phone. Fortunately, I have found simple and quick ways to edit PDF files on iPhone () and Android phones as well as Mac and PC. I'll walk you through the basics of adding text, signing documents, and filling out forms. The best part is that all the apps and software I recommend are free.

Edit PDF on Mac

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

First, just double-click on the PDF file and it will automatically open in Preview.merge two pdf pages into one page mac If for some reason this doesn't open, open the Applications folder and then open Preview, which is the icon with the ocean postcard and the little magnifying glass in the corner. From there, you'll see 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 file.

To access the toolbar, click the Marker Tool in the upper right corner next to the search field. The icon is the tip of a pencil inside a circle. Click on the text tool - it is the icon of the letter T inside a square - and a text box will appear in the text box. You can move the box anywhere on the page.

To change the appearance of the text, click on the Text Styles tool - it is the icon of an A in italics. If you need to resize the text box, click on any of the blue dots. This will allow you to make the text field wider or narrower by dragging it to the left or right.

There are also drawing and sketching tools. "The Draw tool lets you use the cursor to draw almost anything you need, while the Sketch tool converts the drawn object into a shape with customizable fills and borders. If you're just drawing lines or waves, you can change the color and thickness using the Shape Styles tool (stacked parallel lines) or the Border tool (small squares inside a large square). If you're not feeling particularly artistic, you can also add pre-made shapes.

My favorite tool is the ability to add a signature. Click the arrow next to the Signature tool - the cursive letter J - and then click the Create Signature button. You must choose between signing with your finger using the trackpad or scanning with the Mac's built-in camera.

To use the trackpad, click the Trackpad tab, then click the Click Here to Start button and press any key when you're done signing. If you like your signature, click Done. Another way to create a signature is to sign and scan a piece of white paper. Instead of the Touchpad tab, select the Camera tab. Place the paper in front of the camera and line up your signature on the black line. After a few moments, your signature will appear on the camera preview screen. If you like it, click Done.

To add a stored signature, simply click on the desired signature from the Signature menu. Then drag, resize and reposition it to where you want the signature.

Finally, to save any edits, simply click "Save". You can also export the changes and create a new PDF file.

Mark Up Mode on iPhone

Just like Mac, you need special apps for basic editing on iPhone. Instead of Preview, there is Mark Up mode. Whether you want to edit a PDF inside an email or a file that has been saved in the Books app, tap the Mark Up Mode icon - the circle with the tip of a pencil - to get started. It's practically the same tool that pops up on the screen after you take a screen shot.

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

If you saved your signature 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 from your phone, tap Add or Remove Signature, then tap the plus sign in the upper-left corner of the screen. Use your finger to sign on the line and tap Done to save.

When adding edits to a PDF file, you can use the left and right undo arrows at the top to move forward or backward in order to add content. However, there is also an eraser tool available to remove any unwanted drawings, sketches, or highlights you have made, regardless of the order in which you made them.

Once you've finished editing, you can reply with an updated PDF via email, or if you're inside the book, you can AirDrop, email, or print via the iOS Share menu.

Adobe fills in and logs in on Android

Unfortunately, there are no system-level PDF editing tools built into the Android operating system, but fortunately, there are a seemingly endless number of apps for editing PDF files in the Google Play store. For the basics, especially forms, I like Adobe Fill and Sign, which is free in the Play Store.

First, open Adobe Fill and Sign and select your PDF file. The first time you open the app, you have the option to set the app to open anytime you open a PDF file. Once the file is open, click anywhere on the screen to add a text box. After entering text, you can move the box by clicking and dragging. You can resize the text box using the upper and lower case letters As in the top bar of the text box.

Adobe Fill & Sign is a free app for Android phones!

Adding a signature and initials is easy.Adobe Fill & Sign limits you to a signature and a set of initials. The first time you tap the tool, a signature line will appear on the screen. Sign or initial with your finger. If you want to change a saved signature or initials, just click the X. on the right side of the tool.

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