Getting Started With DeckMerge — Your First Merge & Common Fixes
By Josh Comstock · Updated June 2026 · ~6 min read
DeckMerge does one thing, and it tries to do it with as little ceremony as it can get away with — turn several presentations into one clean file, right on your own computer. So this is the short version: how to run your first merge, then fixes for the handful of things people actually ask about.
What You Need
DeckMerge runs on Apple Silicon Macs (M1 or newer) on macOS 13 Ventura or later, and a Windows 10/11 version is on the way. There's no account to create — you download the app, start the 14-day free trial, and you're merging. After the trial it's a one-time $29 — a 3-seat license with lifetime updates. Two of the input formats lean on the app that owns them: opening legacy PowerPoint (.ppt) uses Microsoft PowerPoint, and Keynote (.key) uses Keynote on your Mac. Modern .pptx and .odp need nothing extra.
Your First Merge, Step by Step
- Add your files. Drag the presentations you want to combine into the drop zone. PowerPoint, Keynote, LibreOffice Impress, and downloaded Google Slides can all go in together — mix and match freely.
- Put them in order. Drag the rows to arrange the decks the way you want them to play. This is the order the final presentation follows, top to bottom.
- Choose a canvas. Pick Auto, 16:9, or 4:3. Auto is the safe bet — if your decks mix aspect ratios, each slide is fitted onto the chosen canvas with its proportions preserved and centered, never stretched.
- Add separators if you want them. Optionally drop a black, white, or blank slide between decks, and open or close the merge with a blank title or end slide. Skip it and nothing's lost.
- Export. Choose your output — PowerPoint, Keynote, or LibreOffice Impress — and DeckMerge writes one merged file to your computer. Or connect Google to publish straight to Google Slides (within Slides’ upload limits). The merge itself is never uploaded.
And that's the whole flow. For most merges it's add files, glance at two options, export. Done.
Common Questions & Fixes
A Font Changed in the Merged Deck
If a slide's text looks different after merging, here's what happened: the original used a font that isn't installed on the computer doing the merge, so the system reached for the closest match it had. Install the missing font (or embed fonts in the source deck before merging), then merge again. And to be clear — this is the same substitution PowerPoint and Keynote do whenever a file moves to a machine that lacks its fonts. It isn't unique to merging.
A Video Won't Play After Merging
DeckMerge carries each slide's embedded media into the merged file, so a clip that was truly embedded should keep playing. If one doesn't, the culprit is almost always the same: it was linked rather than embedded in the original — the source slide pointed at a video file sitting elsewhere on the author's disk, so there were no media bytes to carry in the first place. Re-embed it in the source (in PowerPoint, Insert → Video → This Device), then merge again. There's a fuller explanation in merging PowerPoint without losing video.
The Merged File Is Very Large
A big output file is usually a good sign — it means the embedded videos and high-resolution media actually came across rather than getting stripped on the way in. But if you do need something smaller, compress the videos in the source decks before merging, or export and then run PowerPoint's own media-compression on the result.
A Keynote File Won't Add on Windows
Keynote (.key) is macOS-only, because Keynote is an Apple app — so the Windows version (launching soon) won't read it. The fix is straightforward: open the file on a Mac and export it to PowerPoint (.pptx) first, then add that to your merge. On Windows, DeckMerge will work with PowerPoint, OpenDocument, and Google Slides.
Slides From Different Decks Still Look Different
That's intentional — it's not a bug. DeckMerge duplicates each deck's theme into the merged file instead of flattening everything onto one template, so every section keeps its original styling. But if you want a single consistent look, apply one theme to the source decks before merging, or unify the design in your presentation app afterward.
Is the Merge Really Local?
Yes. The merge runs entirely on your machine — nothing is uploaded to produce your file, and there's no telemetry. The only outbound features are opt-in and clearly labeled: checking for updates, and publishing a finished deck to your own Google Slides if you connect Google (within Slides’ upload limits). That's it. Details are in the privacy policy, and the reasoning behind it is in merging presentations offline.
Still Stuck?
If something isn't behaving, just email studios@peaceharbor.com with the formats you're merging and what you're seeing — and tell us which apps the source decks came from, because that's usually the detail that cracks it.
Related: How to Merge PowerPoint Files Without Losing Embedded Video · How to Combine PowerPoint, Keynote & Google Slides into One Deck · How to Merge Presentations Offline Without Uploading.