spf13/viper

Prefer this fork only if you specifically want its trimmed feature set and can accept major upstream lag. Most adopters needing broad config-source support or current maintenance should stay on upstream Viper.

This fork is materially different enough that adopters should validate long-term maintenance and upgrade cost.

Prefer this fork if you want a maintained, simplified Viper and do not depend on remote config or HCL. Prefer upstream if you need the full breadth of Viper features or want the safest path for long-term compatibility.