Translate a JSON file with POEditor following the steps below:
1. Create localization project
Log in to your account, create a new translation project and add a language to it (the software's default language).
2. Import JSON file
In the project page, click on "Import Terms" in the Options Menu on the right, to upload the strings from your key-value JSON file. Don't forget to choose to "Also import translations to..." the language you added at step 1.
This language will automatically be set as your project's Default Reference Language after you import the translations. You can change the DRL in Project Settings.
3. Start strings localization
Add the languages you want your app to be localized in, invite contributors to join the translation and start localizing your app.
When you are done with the localization, you can export your localized languages to your computer by using the Export function in any Language page.