Highlighting text in a PDF is one of the most common annotation tasks. Whether you are marking up a research paper, flagging clauses in a contract, or reviewing a report, highlights let you call out specific passages for later reference without altering the underlying document.
The main distinction that matters is whether you need highlights that remain editable and visible to others in a collaborative review, or highlights that are permanently part of the document for sharing or printing.
How PDFHaul Highlight Works
Go to highlight pdf, upload your PDF, and use the highlight tool to select and color text passages. PDFHaul supports multiple highlight colors so you can use different colors for different categories or themes.
When you download the document, highlights are flattened into the page. They cannot be removed or edited after download. Files up to 50MB are supported, no account is required, and files are automatically deleted after two hours.
Using Multiple Colors Effectively
Multiple highlight colors become useful when you are categorizing passages rather than just marking them. Some approaches that work well in practice:
By importance: yellow for general interest, orange for key points, red for critical items that need action.
By theme: one color per topic when reviewing a document that covers multiple subjects. Makes it easy to scan for all passages related to a specific theme.
By reviewer: if multiple people are marking up the same document sequentially, each person uses a different color. Effective when highlights are not editable layers but each reviewer adds their own color on top.
Editable vs Flattened Highlights
PDFHaul flattens highlights on download. This is appropriate when the document is a final version being shared or printed. If you need highlights that the recipient can see as separate annotation layers (for example, in a review workflow where they need to respond to or remove specific highlights), use Adobe Acrobat Reader or a similar tool that preserves annotation layers.
Highlighting Scanned PDFs
Highlighting in a scanned PDF works differently from highlighting in a text-based PDF. In a text-based PDF, you select text and the highlight applies precisely to those characters. In a scanned PDF, there is no selectable text, so you are drawing a highlight shape over an image of text.
PDFHaul's highlight tool works on both. For scanned PDFs, use the shape-based highlight rather than text selection. The visual result is the same.
How Free PDF Highlight Tools Compare
PDFHaul
Free, no account, multiple colors, 50MB limit, flattened on download, files deleted after two hours. No daily limit.
Adobe Acrobat Reader
Free desktop application with highlight tools that preserve annotations as editable layers. Multiple colors. Annotations can be shared with other Acrobat users. The best option for collaborative review workflows. No file size limits for local files.
Preview (macOS)
Built-in highlight tool on Mac. Free, offline, unlimited. Highlights are saved as editable annotations in the PDF. A good default for Mac users who do not need to collaborate.
Smallpdf and iLovePDF
Both offer highlight tools online with daily free limits. Suitable for occasional use.
Frequently Asked Questions
Can I remove a highlight after downloading?
No. PDFHaul flattens highlights into the page on download. They are permanent in the output file. If you think you may need to remove or adjust highlights, keep the original PDF and re-highlight if needed.
Can I highlight a scanned PDF?
Yes. For scanned PDFs, PDFHaul places the highlight as a color shape over the image rather than over selected text. The visual result is the same.
How many colors are available?
PDFHaul offers multiple highlight colors. Use different colors to categorize or prioritize passages.
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Written by PDFHaul Team
Expert team specializing in PDF processing and document management. We share practical tips, tutorials, and best practices to help you work smarter with PDFs.
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