JSON viewer for OS X

Jsoneditor is a browser-based editor that you can deploy locally or use the ad-sponsored online version provided by the author. It's handy for small JSON files, and I find it the easiest and most feature-full. It will highlight broken json, but it's not a 100% compatible validators like https://jsonlint.com/ because, for example, it treats raw tabs as valid within strings although this is not allowed by the JSON spec.

JSONMate seems to be a usable open-source project with an online editor which probably won't be able to handle large files, but you can fork it on github, adapt to your needs and run it locally.

Intellij Idea and derivatives have decent JSON support but large files take time to load.

SublimeText is also usable for JSON if you install the plugins for beautifying and extra features.

For windows XMLMarker does a good job as an XML and JSON visualizer, but the last version which added JSON support is a limited trial.

Disclaimer: I am not affiliated with any of these tools and projects.

Checkout Jason, although it appears to be no longer maintained since Osx 10.7, I just opened a JSON in it with Osx 10.11 and it works ok.

Please Note: since it is no longer maintained it is likely going to be unreliable.

Alternatively, I have opted for an online browser-based JSON editor:

• http://jsoneditoronline.org/

It is surprisingly fast, allowing you to browse the tree, search values, edit values, insert values, reorder values, even duplicate values. You can even drag and drop stuff around to really get creative :) Unfortunately, you can't see the filename of the json you are editing, but you can open up new browser tabs for multiple json file editing at once.