go install github.com/svennergr/originmap@latest
originmap will unpack a sourcemap JSON provided via stdin. The program will unpack the files into the directory defined by the -o flag. If no directory is specified, the ./out directory is used by default.
This repository contains a sample sourcemap at ./example/main.js.map, which can be parsed back to it's sources via the following command:
cat example/main.js.map | originmap
This will create a directory with the files main.js and random.js.