PosteRazor for Mac: Download & Install Guide
Want to turn one big image into a multi-page PDF poster on your Mac? PosteRazor — the classic free and open-source “poster printer” — does exactly that: it slices a single image across as many standard-size pages as you need, so you can print it on an ordinary home or office printer and tape the sheets together into a wall-sized poster. No wide-format printer required.
There is one important caveat for Mac users: the official Mac build of PosteRazor is old. It dates from the Intel era, and no native Apple Silicon (M1 / M2 / M3 / M4) version was ever released. The good news is that the old build still works on modern Macs. This guide shows you how to download it, install it, get past Gatekeeper, and run it under Rosetta 2 — plus a zero-install alternative if you’d rather skip the hassle.
sudo xattr -rd com.apple.quarantine /Applications/PosteRazor.app in Terminal. Prefer zero install? Use PosteRazor Online in your browser.
Download PosteRazor for Mac
The Mac build is hosted on the official SourceForge project page. The button below goes through our download redirect:
Version note: the last stable release of PosteRazor is v1.5.2. The Mac package corresponds to the v1.5.x line — it is old, but it is the genuine official build. If you want to double-check the file, compare it against the official SourceForge project page before running it.
What Mac version of PosteRazor actually exists?
To set expectations honestly, here is the full picture:
- No native Apple Silicon build. PosteRazor’s development slowed down years ago, and no universal or ARM64 Mac binary was ever released.
- The Intel build still works. Apple Silicon Macs run Intel apps through Rosetta 2 translation, and PosteRazor is a lightweight image-processing tool — it runs fine under Rosetta.
- Intel Macs run it natively. If you still have an Intel-based MacBook, iMac, or Mac mini, the app runs as-is with no translation layer.
- The interface looks dated. Expect an old-school wizard-style window rather than a modern macOS app. Functionality is what matters here, and it works.
- Output is a standard PDF. Whatever Mac you use, the end result is a normal multi-page PDF you can print from Preview on any printer.
Step-by-step: make your first poster on Mac
Once PosteRazor is running, the workflow is a simple 5-step wizard:
- Load your image. Click through the file picker and choose a high-resolution image. Higher resolution means sharper poster tiles — aim for at least 150 DPI at your target poster size if you can.
- Set the paper. Choose your paper size (A4, Letter, etc.), orientation, and margins to match the paper loaded in your printer.
- Set the overlap. PosteRazor can add a small overlap border between tiles so you can align and glue sheets precisely. A 5–10 mm overlap is a good starting point.
- Set the layout. Decide how big the final poster should be — either by entering exact dimensions or by choosing how many pages wide and tall the poster will be. The preview shows exactly how the image will be sliced.
- Save the PDF. PosteRazor generates a multi-page PDF. Open it in Preview, print every page at 100% scale (disable “fit to page”), then cut, align, and tape the sheets together.
Install on an Intel Mac
- Download the Mac package using the button above.
- Open the downloaded
.dmgfile — a Finder window containing the PosteRazor app icon appears. - Drag PosteRazor.app into your Applications folder.
- Eject the disk image.
- Launch PosteRazor from Applications or via Spotlight. If macOS blocks it, see the Gatekeeper section below.
Run on Apple Silicon (M1 / M2 / M3 / M4) via Rosetta 2
Rosetta 2 is Apple’s translation layer that lets Intel apps run on Apple Silicon Macs. Most M-series Macs already have it installed; if not, macOS offers to install it automatically the first time you open an Intel app.
- Install PosteRazor exactly as described above (drag to Applications).
- Double-click PosteRazor. If macOS says you need Rosetta, click Install and wait for it to finish.
- Launch PosteRazor again — it should now open normally.
- (Optional) To confirm: select PosteRazor.app in Finder, press ⌘I, and check “Kind” — an Intel app running under Rosetta shows as “Application (Intel)”.
Performance is a non-issue here: slicing an image into poster tiles is not CPU-heavy, and Rosetta 2 handles it with ease.
macOS Gatekeeper is blocking PosteRazor — how to fix it
Because the app is old and not notarized by Apple, Gatekeeper will very likely refuse to open it on first launch with a message like “PosteRazor cannot be opened because the developer cannot be verified” or “PosteRazor is damaged and can’t be opened.” This is normal for old unsigned software — the file itself is the genuine official build. Two ways around it:
Option 1 — the simple way (no Terminal):
- In Finder, open your Applications folder.
- Right-click (or Control-click) PosteRazor and choose Open.
- macOS shows a warning dialog with an Open button this time — click it.
- You only need to do this once; later launches work normally.
Option 2 — Terminal (removes the quarantine flag entirely):
Open Terminal and run:
sudo xattr -rd com.apple.quarantine /Applications/PosteRazor.app
Enter your Mac login password when asked (it won’t show as you type — that’s normal), then launch PosteRazor from Applications.
Print tips for the best results
- Start with a big image. A poster made of 12 A4 sheets is roughly 3× the width of one sheet — your source image should have enough pixels to stay sharp at that size.
- Print at 100% scale. In the macOS print dialog, make sure scaling is set to 100% and “Scale to fit” is off, or your tiles won’t line up.
- Use the overlap. The overlap margin PosteRazor adds makes trimming and aligning sheets far easier — don’t set it to zero on your first try.
- Test with 4 sheets first. Before committing to a 20-sheet monster, do a small 2×2 test to check colors, alignment, and your taping technique.
Quick comparison: your options on Mac
| Option | Install needed | Works on | Best for |
|---|---|---|---|
| Mac app (Intel build) | Yes (+ Rosetta 2 on M-series) | Intel & Apple Silicon Macs | Offline use, repeated poster jobs |
| PosteRazor Online | No — runs in the browser | Any Mac with a modern browser | One-off posters, locked-down Macs |
Frequently asked questions
Is there a native Apple Silicon (M1/M2/M3) version of PosteRazor?
No. No official ARM64 Mac build has ever been released. The Intel build runs on Apple Silicon Macs through Rosetta 2, which macOS installs automatically the first time you open an Intel app.
Is PosteRazor safe to install on a Mac?
PosteRazor is free and open-source software, and the Mac package linked here is the official build. Gatekeeper warnings appear because the app is old and not notarized — not because it is malware. As with any old software, download only from the official SourceForge project page (or our redirect to it), and avoid repackaged downloads from random websites.
Why does macOS say PosteRazor “is damaged and can’t be opened”?
That message is Gatekeeper’s way of blocking unsigned software on newer macOS versions. Use the right-click → Open method or the xattr Terminal command described above; both are standard workarounds for legitimate older apps.
Which macOS versions are supported?
The build dates from the Intel era, so it was designed for much older macOS versions — but it continues to launch on modern releases via Rosetta 2. If a future macOS version ever drops Rosetta 2, the online tool remains a working fallback.
Can I just use PosteRazor in my browser instead?
Yes. PosteRazor Online runs the same poster-splitting workflow in any modern browser on your Mac — no download, no Gatekeeper dialogs, and no Rosetta needed.