There is a rest API, https://keybase.io/__/api-docs/1.0 https://keybase.io/__/api-docs/1.0 Additionally, I have used GPG and their website with javascript base

There is a rest API, https://keybase.io/__/api-docs/1.0 https://keybase.io/__/api-docs/1.0 Additionally, I have used GPG and their website with javascript based crypto in some cases without using their NPM app. I believe their goal is to get other client implementations out there on the public api.