Convert Git logs to JSON. The first script (git-log2json.sh) is all you need, the other two files contain only optional bonus features :)

git-log2json.sh

#!/usr/bin/env bash

# Use this one-liner to produce a JSON literal from the Git log:

git log \
    --pretty=format:'{%n  "commit": "%H",%n  "author": "%an <%ae>",%n  "date": "%ad",%n  "message": "%f"%n},' \
    $@ | \
    perl -pe 'BEGIN{print "["}; END{print "]\n"}' | \
    perl -pe 's/},]/}]/'

git-stat2json.sh

#!/usr/bin/env bash

# OPTIONAL: use this stand-alone shell script to produce a JSON object
# with information similar to git --stat.
#
# You can then easily cross-reference or merge this with the JSON git
# log, since both are keyed on the commit hash, which is unique.

git log \
    --numstat \
    --format='%H' \
    $@ | \
    perl -lawne '
        if (defined $F[1]) {
            print qq#{"insertions": "$F[0]", "deletions": "$F[1]", "path": "$F[2]"},#
        } elsif (defined $F[0]) {
            print qq#],\n"$F[0]": [#
        };
        END{print qq#],#}' | \
    tail -n +2 | \
    perl -wpe 'BEGIN{print "{"}; END{print "}"}' | \
    tr '\n' ' ' | \
    perl -wpe 's#(]|}),\s*(]|})#$1$2#g' | \
    perl -wpe 's#,\s*?}$#}#'

merge.js

/*
 * OPTIONAL: use this Node.js expression to merge the data structures
 * created by the two shell scripts above
 */

var gitLog, lstat;

gitLog = require('git-log.json');
lstat = require('git-stat.json');

gitLog.map(function(o){
    o.paths = lstat[o.commit];
});

merge.sh

#!/usr/bin/env bash

# OPTIONAL: Use jq to merge the two JSON files.

jq --slurp '.[1] as $logstat | .[0] | map(.paths = $logstat[.commit])' git-log.json git-stat.json