Highlight Form Fields
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What is Highlight Form Fields?
Highlight Form Fields draws semi-transparent colored rectangles over every interactive form field in a PDF, making it easy to see where fillable fields are located. The tool uses pdf-lib to iterate over all AcroForm fields and draw colored overlays on each widget rectangle.
The default highlight color is yellow (#ffff00) at 30% opacity, but any hex color can be specified. The overlay is drawn directly on the page content, creating a permanent visual indicator of every form field's position and size.
This is a visual inspection tool — it does not modify the form fields themselves. After highlighting, you can clearly see which areas of the document are interactive (fillable) versus static content, useful for form auditing and quality assurance.
The tool iterates over every AcroForm field in the document, extracts each widget rectangle (position and dimensions), and draws a semi-transparent filled rectangle at that location. Fields with multiple widgets (like radio button groups) have each widget highlighted individually.
How to Use Highlight Form Fields
- Drop a PDF with form fields onto the upload zone, or click to browse and select it.
- Optionally specify a highlight color as a hex code (default: #ffff00 yellow).
- Click Highlight Fields. The tool iterates over all AcroForm fields and draws semi-transparent colored rectangles over each widget.
- A download button appears with your file, named
highlighted-fields.pdf. All form fields are now visually highlighted.
Why Use Highlight Form Fields?
Quality assurance teams reviewing PDF forms need to verify that all expected fields are present and correctly positioned. Highlighting makes invisible form fields visible, ensuring no field is missing or misaligned.
When training users on form-filling workflows, highlighted fields make it immediately obvious where input is expected. The visual guide reduces confusion about which areas are interactive.
Form designers verifying their PDF output use highlighting to confirm that field positions match the intended layout, especially when fields overlap with static content or are positioned near page edges.
Accessibility auditors reviewing PDF forms need to verify that form fields have appropriate sizes, are logically ordered, and are positioned correctly for screen reader navigation. Visual highlighting makes the field layout immediately apparent.
Privacy & Security
Your files never leave your browser. Every step — loading the PDF, iterating form fields, drawing highlight rectangles, and saving the output — happens on your own device using pdf-lib. Nothing is uploaded to Racira's servers, no copies are stored in the cloud, and no file data is transmitted at any point.
Frequently Asked Questions
Can I change the highlight color?
Yes. Specify any hex color code (like #ff0000 for red, #00ff00 for green, or #0000ff for blue) in the color field. The default is yellow (#ffff00). The highlight is drawn at 30% opacity so the underlying content remains visible.
Does this affect the form fields?
No. The highlight rectangles are drawn on the page content layer, behind the form field widgets. The form fields remain fully functional — users can still click, type, and interact with them normally. The highlight is purely visual.
What if the PDF has no form fields?
The tool reports that no interactive form fields were found and returns the document unchanged. Common reasons for no fields: the PDF is a flat image, the form was created as static text rather than interactive widgets, or the fields use a non-standard form system.
Can I highlight only certain types of fields?
Not with this tool — it highlights all form fields uniformly. To highlight specific field types, you would need to extract the field inventory first (using Form Field Extract), identify the fields you want, and manually add highlights using a PDF editor.
Can I print the highlighted version?
Yes. The highlight rectangles are part of the page content, so they print just like any other content. The semi-transparent yellow overlays will appear on the printed output, making form fields visible on paper.