There's more than one good option out there for combining JW Library backups. Here's where JW Fusion focuses its energy, so you can see if it's the right fit for you.
A few free tools exist for this, and most of the good ones share the same basic promise: your backup files are processed locally in your browser and never uploaded anywhere. That part isn't unique to JW Fusion, and it shouldn't be — it's simply how a tool handling personal study data ought to work.
Where JW Fusion tends to differ is in scope. Some tools branch out into note browsing and editing, duplicate cleanup, study statistics, or a community forum — genuinely useful if that's what you're looking for. JW Fusion stays deliberately narrow: it merges your backups, correctly and completely, and gets out of your way. No account, ever, and nothing else to learn.
A few practical things also set JW Fusion apart: it's available as a real native app for Windows (not just a browser tool), free with no tiers or upsells, and works the same whether you're merging two backups or seven.
If you want a fuller toolkit around your JW Library data, it's worth exploring what else is out there — there's no one right answer. If you just want your backups combined cleanly and privately, that's exactly what JW Fusion is built for.