Willow vs Zap: What are the differences?

Developers describe Willow as "A powerful, yet lightweight logging library written in Swift, by Nike". Willow is a powerful, yet lightweight logging library written in Swift. On the other hand, Zap is detailed as "Blazing fast, structured, leveled logging in Go (by Uber)". Zap takes a different approach. It includes a reflection-free, zero-allocation JSON encoder, and the base Logger strives to avoid serialization overhead and allocations wherever possible. By building the high-level SugaredLogger on that foundation, zap lets users choose when they need to count every allocation and when they'd prefer a more familiar, loosely typed API.

Willow and Zap can be categorized as "Logging" tools.

Willow and Zap are both open source tools. Zap with 7.22K GitHub stars and 553 forks on GitHub appears to be more popular than Willow with 1.13K GitHub stars and 61 GitHub forks.