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PDF annotation: How it works and use cases

10 min read
Katie Oberthaler

If you’ve ever tried to edit or annotate a PDF file, you’ll know it’s not as straightforward as reviewing and commenting on an MS Office or Google Workplace document.

Yet, the Portable Document File (PDF) remains a favorite file type, especially among creative and marketing teams. 

To be fair, the PDF was never intended to be an editable file type. It was supposed to be the on-screen equivalent of a hard copy printout that preserved color accuracy and formatting, and allowed teams to review assets before printing. 

But naturally, reviewers wanted to correct typos, suggest color enhancements, and leave comments in the PDFs. And so today, we now have PDF editors and annotation tools to do just that. 

Except, PDF files are notoriously tricky to edit, and some tools only allow you to leave comments.

In this guide, we’ll explore the primary use cases for PDF annotation tools, give you a checklist of features to consider when buying PDF annotation software, and finally present four PDF annotation tools for you to compare.

What we'll cover

What Is PDF Annotation?

PDF annotation describes the practice of adding any extra text, graphics, or objects to a PDF document. 

Annotations are essential in PDFs as you can’t add comments as you can in MS Word or Google Docs during a review and approval process.

You’ll need specialist software (see later) to make PDF annotations such as adding text boxes, formatting text with highlights, underlines, and strikethroughs, or inserting sticky notes, shapes, and freehand drawings. 

For example, in the review and approval process, you could add a comment about the layout of the asset in a sticky note so that everyone can review and act accordingly within the PDF file.

What Are the Main Use Cases for PDF Annotation?

PDF annotations are beneficial for a variety of reasons. Let’s take a look at some of the scenarios where they would prove helpful.


Whether you’re writing a novel, legal contract, or advertising copy, you’ll want a proofreader to review your content before it gets published. 

By saving your work as a PDF document, you know other people can read but can’t edit the content. Instead, they can add annotations detailing what they believe needs removing or changing and highlighting sections that need discussing further. 

PDF annotations ensure your original content remains intact but allow proofreaders to make valuable suggestions.

Making notes

PDF annotations are extremely helpful when you have complex documents, such as technical specifications. 

For example, as you read through the document, you can add notes of anything significant or questions that come to mind that you need to follow up on later. 

You could also add notes to track what you have or haven’t implemented from the instructions so that new team members know what to do.

Art and design feedback

You can add PDF annotations when you’re reviewing and approving creative assets. For example, you might want to ask the designer to change the look of the CTA: “I can hardly see the CTA – could you make it more visible?” Or change the background color: “Could you make the sky darker blue?”

[Image: Collaborating and annotating on PDF docs inside Ziflow.]

Ad proofing

PDF annotations are indispensable when your marketing, creative, and design teams are collaborating on your latest ads. You can review the copy and images for print and digital ads and even run side-by-side comparisons so that you produce higher quality ad designs faster with fewer errors, versions, and revisions.

[Image: proofing ad creative in Ziflow.]

Wireframe annotations

Web designers use wireframe annotations to explain how an on-screen feature should work. A wireframe annotation can include details outside the visuals, such as scenarios, edge cases, or flow examples.

You can use them to guide internal teams, like your developers and copywriters, plus clients, so everyone involved can provide feedback.

Compliance review

Marketers working in the Healthcare, Pharmaceuticals, and Wellness sectors must ensure their creative content meets internal and external compliance guidelines. Failure to do so can result in hefty fines.

PDF annotations allow the compliance personnel, such as your legal and marketing teams, plus regulatory bodies, to review and approve all types of campaigns. 

Other companies with strict brand guidelines regarding colors and word usage can also use PDF annotations in their review and approval process. 

Contract review

PDF annotation is not only helpful in reviewing creative assets but also legal documentation like contracts and agreements.

By saving a legal document as a PDF, reviewers can only read the content. However, they can annotate the content with what and why needs changing, so the original content remains intact. 

Catalog and magazine review

Both digital and print catalogs and magazines have to undergo several review stages. Handling multiple pages would be tricky, especially center spreads with images and words that span two pages. But by saving all pages as a single PDF file, reviewers can toggle back and forth and propose suggestions and changes with annotations. 

Online PDF proofing is particularly useful for high-volume print jobs where you’re checking and comparing the accuracy of changes, such as the colors, text, and pixelation of design elements. It saves on printing costs and any re-printing errors.

Remote collaboration

Remote marketing teams can't gather around a PDF at the office and provide feedback. They need a way to share instant feedback that's not via email, Slack, or some other digital channel where it might get lost.

It's not only that comments and requests will get lost, but these other channels don't have the correct markup capabilities.

Remember, PDF proofing and annotation often require a detailed level of markup and comparison, plus lots of commenting that you can't achieve in other digital channels like Slack and email.

Features for PDF Annotation

Here are the key features to consider when evaluating PDF annotation software.

Color accuracy and comparison

When you convert a PDF file into a proof, many PDF annotation tools cannot reproduce the true definition of colors. Some tones can appear darker or lighter, or the color separation is inaccurate, and consequently, the review and approval process becomes flawed.

Maintaining color accuracy on a PDF proof is incredibly important because it ensures that designers, creative teams, and clients are looking at the right version of an asset. When there is no confusion or debate over the true appearance of design elements when different stakeholders are reviewing an asset, PDFs can be reviewed and approved much faster.

Image transparency 

[Source: PDF Proofing]

Image transparency is another common element in many designs. But not all tools can handle this, which means reviewers are not reviewing an accurate representation of the original design. Again, concerns over image transparency can delay the review process. 

Font quality and pixelation  

Most PDF annotation software handles fonts quite well. But one thing to check is the pixelation of text when zooming in. The text quality can drop significantly on some tools, even at 200%. 

Measurement Tools for Correct Formatting and printing

Maintaining PDF formatting accurately between the source file and the PDF proof saves creative and design teams countless hours during the review process.

Measurement tools that enable you to review down to the pixel, millimeter, or inches provide a more accurate way to check page size, bleed size, or the size of an object on a proof. 

measurement gif

With these tools, reviewers can accurately review what a file will look like at print, which helps clients avoid an erroneous print run and save thousands of dollars in printing costs. 


Highlighting allows you to draw attention to specific text or design element. For example, you might want a section of text in a larger font size or a different color. Highlighting provides precision in the review and feedback process, progressing changes between versions faster and more accurately. 


Strikethrough function 

If you want to indicate any text that you'd like removing, then you’ll need a strikethrough function to correctly indicate in detail what should be changed. 


Comment placement 

Any comments you make must align to the correct part of the PDF so that the designer or reader can apply changes correctly in the next version. 

For example, this is how design agency MRM Global uses Ziflow's PDF annotation and commenting tools to review PDF documents for its clients' events and menus. 

comments mrm global

Conversation and Version history 

With multiple parties involved in your review and approval process, it's essential that they can follow the conversation and comment history sequentially, see who requested changes, and the details of those changes. It’s also imperative that these changes also relate to the versions, so you can compare both the visual changes and the conversation around those changes across PDF iterations. 

version comparison

Upload and load speeds

PDFs often include many, many pages in one document. Often, PDF proofing involves several related PDF documents. Uploading and loading these volume-heavy documents can tax certain software and PDF tools, and slow upload and load speeds only delay the review and approval process. If your designer sends a PDF file to a client for review, the reviewer should be able to check the file straight away and make any annotations without lags or wait times. 

Make sure your PDF annotation software can upload and load swiftly, for all team members. 

Automated approval workflows

Finally, check that your PDF annotation software includes automated approval workflows with notifications, so stakeholders know when they need to review PDF files and your team knows when clients have left feedback and approved changes.

Stage approvals are especially critical for PDFs that contain a lot of information that needs approval by several people or require several or ongoing rounds of review, such as legal documents. 

PDF annotation review workflow templates also help streamline repeatable PDF annotation review process for project-heavy agencies. For example, if you are a print shop doing the same type of high-volume projects or incoming daily design requests, you can apply a PDF review workflow to automate the design and review steps across projects. 

Intake Forms 3 Ways to Bring Content From Clients into Your Creative Production Workflows (Without Using Email)[Image: Setting automation triggers for review and approval inside Ziflow.]

Here is an example of how direct mail agency Dynamicard automates the review of its design files and artwork for clients. Using PDF file conversion, automated workflows, and 24-hour review deadlines and reminders, it is able to turn a large quantity of PDF-based projects within hours and days. 

dynamicard flow

Automatically Convert Other Files to PDF 

Similarly to upload and load speeds, you’ll want to look for a tool that can convert other types of media to PDF for review. This is useful if you have a number of wireframes or other design files from Photoshop, Adobe, and more that you want to convert into one or several PDFs for other team members or clients to review because they may not be able to open or work with these design files natively. 

You can combine PDF conversion options with automated approval workflows to automatically transform files from other applications or formats into PDFs, automatically put them in project folders, and initiate the right review workflows. This saves your designers and project managers a ton of manual work both converting files and follow-up sending PDFs for review. It’s all automated behind the scenes.


Final Thoughts

Not all PDF annotation tools are created equal, so it’s important to weigh up the benefits and see which software fits your requirements. 

While Adobe Acrobat Reader provides some basic annotation features, it won’t stand up against the other tools.

On the other hand, Ziflow’s PDF editing and annotation capabilities, processing speed, color accuracy, version comparison, conversation history, and automated approval workflows set it apart from the competition, especially for organizations that handle a high volume of PDF proofs every day.

Katie Oberthaler

Read More: How Dynamicard Modernized the Direct Mail Campaign Launch Process

Learn how a high-volume print shop used PDF annotation to accelerate project deadlines and client review.

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