Preview on Mac vs a browser PDF viewer

Preview on Mac is the most capable free PDF editor most people already own: it marks up, signs, fills forms, merges by dragging thumbnails, compresses with a Quartz filter and even redacts for real. This browser viewer does not replace it on a Mac; it adds OCR, which Preview lacks, and it works identically on Windows, Linux and ChromeOS with nothing to install.

What Preview does well

Preview is built into macOS and handles most PDF tasks without a third-party app:

• Markup toolbar: highlight, underline, strikethrough, shapes, arrows, text boxes, speech bubbles, sticky notes, freehand sketch with shape recognition.
• Sign: create a signature with the trackpad, the camera or an iPhone, store it, and place it on any page.
• Forms: fill AcroForm fields; checkboxes and text fields work natively.
• Pages: rotate, delete, reorder in the thumbnail sidebar; merge by dragging pages or whole PDFs from another window into the sidebar.
• Compress: File, Export, Quartz Filter, Reduce File Size. It shrinks scans dramatically, sometimes at the cost of image quality.
• Redact: Tools, Redact (macOS Big Sur and later) removes the underlying text and image data, not just a visual cover.
• Export to JPEG, PNG, TIFF, and PDF with a password; print with Save as PDF.

If you are on a Mac and the task is in this list, Preview is the right answer and it is free.

What Preview does not do

The gaps are specific but they matter:

• No OCR. A scanned PDF stays unsearchable in Preview. Live Text can select words in an image on screen, but it does not write a text layer into the PDF, so the file is still a scan for Spotlight, Ctrl+F in other apps and screen readers.
• Mac only. There is no Preview for Windows, Linux or ChromeOS, and the iPad has a different Markup implementation.
• No editing of existing text. Like most free tools, Preview adds a text box over the page; it cannot rewrite a paragraph.
• Permission locks. Preview honors owner-password restrictions; a no-print PDF stays no-print.
• Conversion is limited to images; no Word or Excel export.
• Annotation compatibility. Preview sometimes omits appearance streams, so marks made in Preview can be invisible in other readers until flattened, as described in PDF annotations explained.

Comparison table

When to use the browser viewer on a Mac

Three situations:

1. Scanned documents. Open the scan here, click OCR, download. The result searches in Preview, Spotlight and Mail. Recognition runs locally with tesseract.js; language follows your browser (English by default) and long scans take tens of seconds per page. Guide: make a scanned PDF searchable.
2. Locked files. A PDF that opens but refuses to print or copy: Remove Restrictions writes a clean copy. Preview will not do that. Neither tool opens a file that asks for a password.
3. Reading in the dark. The viewer's dark theme is easier on the eyes for long reads than Preview's white pages; see dark mode PDF reader.

For signatures on a Mac both work; Preview's camera capture is convenient, the viewer's drawn signature is enough for most forms. Details in add a signature to a PDF on Mac.

When to use the browser viewer because you are not on a Mac

The honest reason this page exists: people who learned PDF editing on a Mac and now sit at a Windows laptop or a Chromebook search for "Preview for Windows". There is none. The closest no-install equivalent is this viewer, which gives you the markup toolbar, drawn signature, page rotate and delete, merge, and whiteout in any browser, plus OCR. For compression and true redaction on Windows you will need a desktop program such as PDF24 or a paid editor; the best free PDF editors page lists them.

Everything in the viewer stays on your device, which matches Preview's privacy: the file is opened with pdf.js in the tab and saved with pdf-lib, and the only network fetch is the OCR engine's language data from a CDN.

Frequently asked questions