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 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.
Learn how a high-volume print shop used PDF annotation to accelerate project deadlines and client review.
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.
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.
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.
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.
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.
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 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 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.
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.
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.
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.
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.
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.
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.
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.
PDF Annotation Tools
Now that you have an idea of what features to check let’s take a look at four PDF annotation tools. We’ve included a selection of free and premium tools that you can scale to enterprise-level depending on your requirements.
Ziflow’s online proofing software can take huge PDF files and quickly render them in users’ browsers. Ultimately, this gives reviewers the most accurate transparency, color reproduction, font pixelation, text quality, and more when examining PDF proofs while allowing them to load quickly for review and annotation.
- Collaborate on PDFs alongside images, videos, audio, and 1,200+ other content types.
- Provide clear visual feedback with precise markup and text annotation tools.
- Top-of-the-line and tested features for PDF color accuracy, load speeds, and upload speeds.
- Track changes between versions and highlight the differences automatically.
- Keep reviewers aligned throughout the approval process.
- Increase review efficiency by streamlining approval workflows with powerful automation.
- Work quickly and efficiently with the fastest upload speeds available.
Pros: Ziflow’s PDF processing speed and accuracy, plus its automated approval workflows and detailed side-by-side version comparison, puts it way ahead of the competition.
Cons: Ziflow isn't a project management software, but it integrates with Monday.com and other project management platforms.
Adobe Acrobat Reader
Adobe’s free Acrobat Reader software is the best-known PDF viewer on the market. But the free tool also allows you to sign, collaborate on, and annotate PDF files.
- View, comment, and print PDF documents.
- Annotate PDFs using sticky notes or drawing tools, text highlighter, and markup tools.
- Zoom in on small objects.
- Sign, track, and send limited numbers of PDF files.
Pros: Free reader and annotation tool that’s quick and easy to use.
Cons: Limited functionality in the free tool, but clients may not want to invest in the Acrobat Pro premium version.
Foxit PDF Editor
Foxit PDF Editor is a fast, affordable, and secure PDF tool. It’s the #1 pre-installed PDF software on one-third of all new Windows PCs, and it’s also available on macOS, iOS, Android, and online.
- Edit PDF documents like a word processor.
- Annotate PDFs with a drawing pen and notes highlighter.
- Share, collaborate, and manage feedback in reviews.
- Export whole or partial PDFs to popular file formats (Word, PowerPoint, Excel, RTF, HTML, text, and image formats).
- Organize and manipulate PDF pages to support your workflows.
Pros: Foxit is easy to set up and use, and is similar to MS Office. If you only need basic editing options such as annotation, highlighting, and signing PDFs, the free Foxit PDF Reader will suffice.
Cons: If you want advanced capabilities, like image editing and object shading, you’ll need to pay extra for Foxit PDF Editor Pro (Windows-only).
PDFelement lets you create professional documents, jot down notes, scan text, sign and fill out forms, and more on Windows, Mac, and online. Whichever platform you choose, it’s blazing fast to share, review, annotate, and sign documents with Document Cloud to accelerate every stage of the approval process.
- Review and mark up PDFs using a complete set of commenting tools.
- Easily track comments, monitor changes, and add highlights.
- Take notes, add color highlights, or annotate a scanned file quickly and easily.
- Redact sensitive information before sharing documents
- Manage your work on the go with mobile tools to read, edit, annotate, fill, sign, and share PDFs.
Pros: PDFelement is easy to manage across desktop, mobile, and web. You can choose an individual or team license, and either pay yearly or purchase it outright.
Cons: If you choose the one-time perpetual license, it only includes minor updates, not major upgrades.
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.