JSON Editor Online is described as 'web-based tool to view, edit, and format JSON. It shows your data side by side in a clear, editable treeview and in a code editor'. There are more than 10 alternatives to JSON Editor Online, not only websites but also apps for a variety of platforms, including Windows, SaaS, Mac and Android. The best alternative is VisualJsonEditor, which is both free and Open Source. Other great sites and apps similar to JSON Editor Online are JSONedit, HtmlStrip, JSONMate and Json Editor.
Visual JSON Editor is a JSON schema draft v4 based file editor for Windows: When opening a JSON file, the application auto-generates an editor GUI based on the provided JSON schema. The goal is to make JSON editing more effective and easier for users.