It is very exciting to see GitHub working on code intelligence features for open source.

Many folks are asking how this compares to Sourcegraph, so just thought I'd mention if you like this, you will probably like the Sourcegraph browser extension (https://docs.sourcegraph.com/integration/browser_extension). It provides:

* jump-to-def

* find-refs

* documentation tooltips

* fast, quality code search

* an open plugin API (https://sourcegraph.com/extensions)

with:

* high (in some cases, compiler-level) precision

* across many languages

and supports many code hosts:

* GitHub

* GitHub Enterprise

* GitLab

* Bitbucket Server

* Gitolite

* AWS CodeCommit

* generic git servers

for:

* public code

* private code

* on-prem private code

and:

* the source code is open

* there's a public issue tracker: https://github.com/sourcegraph/sourcegraph

(I am the Sourcegraph CTO :) )