Gist of the nbdiff backend (very rough idea)

nbdiff.py

from flask import Flask

class NBDiffFlask(Flask):
    def set_files(self, file1, file2):
        self.file1 = file1
        self.file2 = file2

app = NBDiffFlask(__name__)

@app.route("/diff.js")
def diff():
    return open('src/JSDiff/diff.js').read()

@app.route("/")
def main():
    return open('src/JSDiff/diff.html').read()

@app.route("/file1.json")
def file1():
    return open(app.file1).read()

@app.route("/file2.json")
def file2():
    return open(app.file2).read()

def main():
    import argparse
    parser = argparse.ArgumentParser(__name__)
    parser.add_argument('file1')
    parser.add_argument('file2')
    args = parser.parse_args()
    app.set_files(args.file1, args.file2)
    app.run()

if __name__ == '__main__':
    main()