Joiner for GoPro documentation

Install Joiner for GoPro

Joiner for GoPro runs on macOS 14 Sonoma or later, on Apple silicon and Intel Macs. After buying, download the app zip from your Polar receipt, unzip it, and drag Joiner for GoPro to your Applications folder.

The app is signed and notarized by Apple. Confirm Open at the normal first-launch prompt.

The app works without a license key. The key in your receipt turns on automatic updates: enter it in Joiner for GoPro → License…. Once a day, the app checks for a new version, shows what’s new, and installs it with Install and Relaunch. Joiner for GoPro → Check for Updates… checks right away. A key works on 3 Macs. To move it to another Mac, choose License… → Deactivate This Mac first. Your receipt always has the latest version, too.

Scan the card

Take the card out of the GoPro and put it in your Mac’s card reader. A GoPro plugged in with its cable doesn’t show up as a disk, so the app can’t see it.

The start screen says “Drop your GoPro’s card or a folder here”, and gets a button with the card’s name, like Scan NO NAME. Click it and the app looks for videos on the card.

For chapters you already copied to your Mac:

Drop a card, a folder or video files on the window.
Click Choose Folder… and pick a card, a folder or the video files themselves. File → Open Folder… (⌘O) does the same.
Click Downloads, Desktop or Movies.
Click Add Folder… to keep a folder you often copy your footage to on the start screen. Right-click it to remove it.

The app also remembers the last 5 folders you scanned. They show under Recent on the start screen, and in File → Open Recent. Right-click a recent folder for Keep on This Screen, Remove from Recent and Clear Recent Folders.

The first time, macOS asks whether Joiner for GoPro can read files on the card. Click Allow. macOS asks the same for Desktop, Documents and Downloads. The app never reads any of them until you click.

How a GoPro splits a recording

A GoPro cuts a long recording into chapters, about 4 GB each on most cameras and about 12 GB on the newest ones with a card of 64 GB or more. The chapters of one recording share the last four digits, and the two digits after the first two letters are the chapter number:

File	What it is
`GX010141.MP4`	Recording 0141, chapter 1
`GX020141.MP4`	Recording 0141, chapter 2
`GX030141.MP4`	Recording 0141, chapter 3
`GX010141.THM`	The thumbnail of chapter 1
`GL010141.LRV`	The low-quality copy of chapter 1, for the GoPro phone app

Older GoPros name the first chapter GOPR0141.MP4 and the next ones GP010141.MP4, GP020141.MP4. Their small files keep the video’s name: GOPR0141.THM, GOPR0141.LRV. The app reads both styles.

The list

After a scan, the window lists what it found, in two parts.

At the top are the recordings your GoPro split, under a header like “4 recordings were split into several files”. Each recording is one row with a thumbnail, the name of the file it will become (GX010141 joined.MP4), and a line like “GoPro · 3 files, 11.8 GB, 26 min”. Click Show the 3 files to see its chapters, each with its size and length. GoPro recordings start ticked.

Below are the other videos, the ones in one piece, like short clips that fit in one chapter. Each row has a checkbox, a thumbnail, the file name, and a line with the date, the length and the size. They start unticked. Select All and Select None are in the header.

What else the scan found is in an Also found line under the list: a chapter whose recording isn’t on the card, a file that can’t be read, or a video of a type the app doesn’t read, like “1 .360 video”. Click it for the details.

Videos from another camera in the same folder are listed too, and can be joined the same way.

Preview a video

Click a row and its video plays in a small panel over the bottom right corner of the list. The checkbox and the grip don’t select a row, so ticking and dragging work as before.

A video in the list plays that file.
A recording plays its first chapter, and the panel’s title says so, like “GX010141.MP4 · chapter 1 of 3”.
A row that says Joined and checked plays the joined file.

The video starts on its own with the sound off. The speaker button in the panel’s title turns the sound on. The up and down arrows move to the next row, and Space plays and pauses. Close the panel with its close button or with Escape.

When a video can’t be played, the panel says “This video can’t be previewed.” and the video can still be joined.

Join

The Join button says what it will do:

Join 2 Recordings when only recordings are ticked
Join 3 Videos into One when only other videos are ticked
Join 2 Recordings and 3 Videos when both are

Each ticked recording becomes its own file. Ticked videos become one more file, in the list’s order, with a row at the top of the videos for it, like “3 videos into one · 5 min · 1.7 GB”.

The bar under the list says where the files go: Save joined files to Movies. That’s your Movies folder unless you click Change…. Under it, the app adds up the space the joins need, like “Needs 17.98 GB. Macintosh HD has 182.4 GB free.” When the disk doesn’t have enough, the line turns red and starts with “Not enough space”, and the Join button stays off until you untick something or choose another disk.

When you save to a folder on the card itself, the bar warns you: “This folder is on the card itself. The joined files will take up space there.”

While it joins, the bar shows “Joining 1 of 2” with the file’s name, and each row shows its stage: Reading, Copying, then Checking. Cancel stops it and leaves nothing half-done behind.

The GPS and motion data

A GoPro saves its GPS position, its speed and its motion sensors inside the video file, next to the picture and the sound. The joined video keeps all of it, chapter after chapter, so apps that read that data see the whole recording.

Names

A recording keeps the camera’s name with ” joined”, like GX010141 joined.MP4.

Videos you tick are named after the day they were recorded, like 2026-10-08.MP4. When they were recorded over several days, the name has the first day and the last: 2026-10-08 to 2026-10-15.MP4.

Joiner for GoPro never replaces a file. When the name is taken, the row says “Name already used” and explains it: “A file named GX010157 joined.MP4 is already in Movies. It won’t be replaced.” Click Save as GX010157 joined 2.MP4 to use the next free name.

To call a joined file something else, click Rename… on its row after the join. Type the new name and press Return, or Escape to leave it as it was. The extension stays the same.

The order of the other videos

The other videos are listed by the date they were recorded, oldest first, and they’re joined top to bottom. To change the order, drag a row by the grip at its right edge, or right-click it and choose Move Up, Move Down, Move to Top or Move to Bottom. Sort by Date puts the date order back.

The chapters of a recording can’t be moved. Their order comes from the camera.

After the join

When a join works, its row says Joined and checked, with Show in Finder, Rename… and Move Originals to Trash… next to it. The bar sums up the run, like “4 files were joined and checked, in Movies.” and “Your original files weren’t changed.”

The app writes the joined video under a hidden temporary name. Then it reads it back from the disk and compares it with the chapters, piece by piece: the picture, the sound and the GoPro’s own data. Then it asks macOS to open the video, and its length has to be the length of the chapters added together.

Only then does the file get its name. If anything is off, the temporary file is removed and the row says Not joined with the reason. Your chapters are where they were.

Free the card

After a join that says Joined and checked, you can remove the originals. Click Move Originals to Trash… on the row for that join, or in the bar for every join of the run.

Nothing moves until you confirm. The confirmation says what’s about to happen, like “Move the 10 original files to the Trash?”, and Keep Originals is the default button, so Return, Escape and Space never remove anything.

On a memory card, the Trash is on the card. macOS keeps a card’s trashed files in a hidden folder on the card itself, so they keep taking up space until you empty the Trash. The confirmation says so: “In the Trash, they stay on NO NAME and keep taking up space there until you empty the Trash.”

When every original is on a card or a drive that can be taken out, the confirmation adds Delete Now. It frees the space right away, and it can’t be undone. On your Mac’s own disk there’s no Delete Now, only the Trash.

Right before it removes anything, the app looks at the joined file once more. It has to be where it was saved, with the same size and date. If you moved it or edited it in the meantime, the originals stay and the row tells you why. A rename with Rename… is fine, since the app follows the new name.

The small preview files

Next to each chapter, a GoPro saves a .THM thumbnail and an .LRV low-quality copy. When the chapters go, the confirmation has a box, ticked for you: “Also remove the 20 small preview files the camera made (482 MB)”.

Ticked, the small files go the same way as their videos: to the Trash with Move to Trash, deleted with Delete Now.
Unticked, they stay where they are.
Only the small files of the videos being removed go, matched by name in the same folder. Another video’s small files stay, and so do files with the same name in another folder.
When the videos have no small files left, there’s no box.

A small file that can’t be removed stays where it is, and the row lists it with macOS’s reason, like “GL020141.LRV was left where it is.”

After it’s done, the row says Originals in the Trash or Originals deleted, and the line under the summary says what went, like “10 original files are in the Trash on NO NAME. They take up space there until you empty the Trash. The 20 small preview files the camera made went with them.” Files in the Trash can still go back with the Finder’s Put Back.

What it reads

Joiner for GoPro reads MP4, MOV and AVI videos. It doesn’t read the .360 videos of a 360 camera: they’re listed under Also found and left alone.

The videos you join have to be recorded with the same settings, like the same picture size. Making different ones fit would mean rebuilding every frame, so the app refuses and names the odd one out.

It doesn’t trim or convert videos. It never changes, renames or removes an original, unless you confirm moving it to the Trash or Delete Now.

Troubleshooting

The GoPro doesn’t show up

A GoPro plugged into the Mac with its cable doesn’t appear as a disk. Turn it off, take the card out, and put it in a card reader. The start screen then shows Scan with the card’s name.

The folder couldn’t be read

If you clicked Don’t Allow when macOS asked, the window says “Joiner for GoPro couldn’t read Downloads. You can allow it in System Settings > Privacy & Security > Files & Folders, then try again.” Click Open System Settings, turn on the folder for Joiner for GoPro, then click Try Again.

A recording with a missing chapter

A recording with a missing chapter can’t be ticked. Its row says “Can’t be joined” and which file to look for: “GX020152.MP4 is missing. This recording has chapters 1 and 3, so it can’t be joined until chapter 2 is back.” Copy that file back to the card’s folder and scan again.

Nothing to Join

The scan found nothing the app can join. Check that you picked the right card or folder. A GoPro keeps its videos in a folder like DCIM/100GOPRO. The sentence under Nothing to Join says what was found instead.

Not enough space

The bar says how much the joins need and how much the disk has, and the Join button stays off. Untick something, choose another disk with Change…, or make room on the disk.

A card formatted as FAT32 can’t hold a file over 4 GB, so the app refuses to save a bigger joined file there and asks you to choose another disk.