jsonlint software package provides validating parser of JSON data structures, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install jsonlint
jsonlint is installed in your system.
Make ensure the jsonlint package were installed using the commands given below,
$ sudo dpkg-query -l | grep jsonlint *
You will get with jsonlint package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | PHP |
| Package | jsonlint |
| Version | 1.4.1-1 |
| Description | validating parser of JSON data structures |
| Sub Section | PHP |