JWLMerge, JWL Manager or JW Sync: choosing a JW Library merge tool
JW Library can back up and restore but not merge. JWLMerge, JWL Manager and JW Sync are three free tools that can. What each does, what it runs on, and which suits you.
JW Library's Restore replaces the whole library with the one in the backup. So once you have studied on two devices, restoring either backup deletes the other device's work, and the app has no merge command to combine them. Several free, independent tools exist to do that instead, and the three people search for most are JWLMerge, JWL Manager and JW Sync.
All three are free, all three work on the same .jwlibrary backup file, and none of them is made by or connected with the makers of JW Library. Where they differ is what you have to install, which devices they run on, and what else they do besides merging. This page sets that out so you can pick the one that fits.
Step by step
Back up every device
In JW Library on each device: Personal Study → three-dot menu → Backup and Restore → Create a backup. Whichever tool you use, these .jwlibrary files are what it works on.
Pick a tool that runs where you are
On a Windows PC any of the three will do. On a Mac or a Linux computer, JWL Manager or JW Sync. On a phone or tablet with no computer to hand, JW Sync, because it runs in the browser.
Merge the backups into one file
Load all the backups into the tool and let it combine them into a new file. Keep the original backups until you have checked the result.
Restore the merged file on each device
Restore the merged .jwlibrary file in JW Library on every device. Each one then carries the notes, highlights, bookmarks and tags from all of them.
JWLMerge
JWLMerge is a free, open-source Windows desktop program, originally written by Antony Corbett, that merges two or more .jwlibrary backups into one. It has a long track record and includes a command-line version for people who want to script it. Two things are worth knowing before you use it: it runs on Windows only, and it has had to be updated each time JW Library changed its backup database. Older copies stopped working after one such change in 2023, and development has since continued in community forks, so make sure the version you download supports backups from the JW Library version you have.
JWL Manager
JWL Manager is a free, open-source desktop program for Windows, macOS and Linux. It is closer to a full editor than a merger: it lets you view, edit and delete the notes, highlights, bookmarks, favourites and playlists in a backup, change colours in bulk, and export notes to a spreadsheet, a text file or Markdown. It can merge directly, or by exporting the items you want from one backup and importing them into another. It suits someone who wants fine control and is comfortable installing a desktop program.
JW Sync
JW Sync is this site. It runs in the browser, so there is nothing to install and it works the same on a phone, a tablet, a Mac or a PC; your backups are read on your own device and never uploaded. Besides merging, it has a Conflict Reviewer for the one case that needs a decision (the same note edited differently on two devices), a tag manager that renames and merges tags across hundreds of notes at once, a way to send someone only the notes under one tag or from one date range, and a search that finds a note by what it means rather than its exact words.
Which one to choose
If you only need to merge, you are on a Windows PC and you already know JWLMerge, it does that job. If you want to edit and tidy a backup in detail on a desktop, JWL Manager has the most controls. If you want to merge from whatever device you are holding without installing anything, or you also want the sharing, tagging and search features, use JW Sync. Whichever you pick, the routine is the same: back up every device, merge, check the result, restore the merged file everywhere, and keep the originals.
Frequently asked questions
- Can JW Library merge backups by itself?
- No. Backup and Restore moves a whole library from one device to another, and a restore replaces what was there. Combining two libraries needs an outside tool.
- Are these tools official?
- No. JWLMerge, JWL Manager and JW Sync are all independent projects, not made or endorsed by the makers of JW Library. They work on the .jwlibrary backup file the app already produces.
- Do I need Windows to merge JW Library backups?
- Only for JWLMerge. JWL Manager also runs on macOS and Linux, and JW Sync runs in any modern browser, including on phones and tablets.
- Will merging change my original backups?
- No. A merge reads the backups and writes a new file. Keep the originals anyway until you have restored the merged file and checked that everything is there.
- Is my data uploaded anywhere?
- The two desktop programs work on files on your computer. JW Sync reads the backups inside your browser, and the files are never sent to a server.