convert CLI

sudo npm i -g convert-cli
convert -c <freeconvert API key>

syntax

list the files you want to convert
and the output format you want to convert to

convert *.png jpeg # converts every png to jpeg in cwd
convert 1.png 2.png jpeg # converts 2 pngs to jpeg
convert 1.png jpeg # converts 1 png to jpeg

freeconvert API

1. create an account at https://www.freeconvert.com/auth/free/signup
2. go to API > API Keys > Create API Key
3. enter a name and click "create"
4. run convert -c <freeconvert API key>