Adobe Acrobat Pro is the default answer to "how do I redact a PDF", and it deserves to be: its redaction is real. Mark for Redaction followed by Apply genuinely removes content from the file. Any comparison suggesting otherwise is wrong.

What's worth examining is whether you need it, and the one step in its workflow that catches careful people.

How Acrobat's redaction actually works

Tools → Redact.
Mark the text or regions to remove. Find Text will mark every instance of a term across the document, which is the feature that earns the licence fee on large files.
Apply. Acrobat deletes the marked content and draws the black box.
Save — ideally as a new file, because the change is irreversible.

There's also Sanitize Document, which strips metadata, hidden layers, attachments and script content. Worth running: metadata routinely carries the author's name and the original filename.

The two-step trap

Marking and applying are separate actions, and marking alone changes nothing. The marks are annotations. A file saved after marking but before applying looks completely redacted — black boxes and all — and contains every word underneath.

This is the single most common way a competent person ships a leaky document. It's not carelessness; the interface shows the finished-looking result at the halfway point.

If you use Acrobat, build the habit: apply, save as a new file, then copy-paste test the output. Select all, copy, paste into a text editor, search for what should be gone.

Where Acrobat earns its price

Bulk marking across long documents via Find Text
Offline processing on a machine you control, which some material demands
Precise region control over exactly which pixels go
Sanitize for metadata and hidden content in one pass
It's already installed, if your organisation has Creative Cloud

For a litigation team working through thousands of pages weekly, that's a straightforward buy.

Where it's overkill

Around $240 a year and a desktop install is a lot for redacting a handful of documents a month. It's also a poor fit if you need to redact something on a machine that doesn't have it, or you want a colleague to handle one file without provisioning a licence.

The alternatives, honestly

A browser-based redaction tool. Ours removes text from the content stream and OCR-reads scanned pages to destroy the pixels, free for one page per document, or $5 for a day or $10 a month for whole documents. No install, and files are processed in memory and discarded within seconds. Limits: one document at a time, and no batch processing — if you need to run 200 files through unattended, Acrobat or a scripted pipeline is the better answer.

LibreOffice Draw. Free, offline, open source. Open the PDF, delete the text objects (don't cover them), export. Genuinely removes content. Complex layouts can shift on import, and it doesn't help with scanned pages, which contain no text objects.

macOS Preview — no. Preview's markup draws annotations. Its "redact" feature in recent versions is better than a plain rectangle, but the safe assumption for any annotation tool is that the content remains until you've tested the output.

Online "PDF editors" generally. Many are annotation tools with redaction branding, and you've uploaded a sensitive document to find out. If a tool doesn't say plainly what it does to the content stream, assume it covers rather than removes.

Comparison

	Acrobat Pro	Browser tool	LibreOffice Draw
Truly removes content	Yes, when applied	Yes	Yes, if you delete objects
Handles scanned pages	Yes	Yes	No
Install required	Yes	No	Yes
Works offline	Yes	No	Yes
Batch / many files	Yes	Not yet	Manual
Cost	~$240/yr	Free tier, $5–$10 paid	Free

Whichever you use

The tool matters less than the verification. Acrobat used incorrectly leaks; a free tool used correctly doesn't. Every redaction, regardless of source, should survive:

Copy-paste test — select all, copy, paste, search
pdftotext file.pdf - — prints every text object regardless of overlays
Zoom on scanned regions — nothing legible through the black
Check embedded images on pages that also carry text
Check document properties for author and filename

Ten seconds each, and they catch essentially every real-world redaction failure.

More detail in how to redact a PDF, and the mechanics of why covering fails in why a black box isn't redaction.

Adobe Acrobat Redaction: How It Works, and Cheaper Alternatives