Cargo Features

[dependencies]
doi = { version = "0.3.0", default-features = false, features = ["proxy", "socks-proxy", "metadata"] }
default = metadata, proxy

These default features are set whenever doi is added without default-features = false somewhere in the dependency tree.

proxy default

Enables proxy-from-env of ureq

socks-proxy

Enables socks-proxy of ureq

metadata default

Enables json of ureq

DOI has 4 features without comments.