A command-line interface to Inja, a C++ string template library loosely inspired by Jinja.
inja input_file_template.html output_file.html
With a JSON data file:
inja -d data.json input_file_template.html output_file.html
# or
inja --data data.json input_file_template.html output_file.html
For a quick overview, refer to this syntax cheat sheet.
For more detailed information, refer to the Inja documentation.