A word of caution: some editors will choke on large files or, in particular, long lines.

Opening a one-line JSON file of a few MB in Emacs can be painful. The editor struggles to handle the long line and the matching-parenthesis-highlighter runs its stack machine down the whole length looking for the closing delimiter.

There are ways to avoid this, like pretty-printing the JSON across multiple lines, or forcing fundamental-mode when large files are opened, but I still haven't set these up as default.