The latest (tip-of-tree) protocol changes frequently and may break at any time. However it captures the full capabilities of the Protocol, whereas the stable release is a subset. There is no backwards compatibility support guaranteed for the capabilities it introduces.
Latest browser_protocol.json version updated:
Date: Mon Apr 24 16:47:21 2017 -0700
Latest js_protocol.json version updated:
Date: Tue Apr 18 19:11:14 2017 +0200