Windows cmd
cmd /c 'copy /y /b *.json output.json'
Windows Power Shell
2 options are here:
Get-Content *.json | Set-Content result.json
Copy-Item *.json output.json
How to wrap joined lines into valid JSON
After merging json files we append commas to the end of each line and bracket around the whole content with [ ] using eg. Notepadd++ for that. Thus we get a valid JSON:
[
{ "Full Year Tax":"145,26$"… },
{ "Full Year Tax":"139,00$"… },
{ "Full Year Tax":"100,00$"… }
]