CLA Assistant – Easily Handle Contributor License Agreements (CLAs)

I was recently asked by a third party to tighten the way contribution IP/license is handled with Py4J[1] and found this service, which looks painless for contributors.

I've been burned in the past by having to physically sign and scan or fax (!) contributor license agreements and I did not want to impose this additional hassle to potential contributors. Anybody has experience with this particular service or other alternatives?

[1] https://www.py4j.org/