Go 1.27 makes encoding/json/v2 default after 5½ years – timeline and benchmarks
After a five‑year experimental phase, Go’s new json/v2 package becomes the default in Go 1.27; the author traces its history, presents on‑machine benchmark comparisons showing faster struct unmarshalling but slower map handling, and reveals three undocumented issues—including format‑tag removal, altered UTF‑8 output, and map[string]any slowdown—that developers must consider when migrating.
