Go 1.27 lands: JSON v2, generic methods, experimental SIMD
Six months after 1.26, Go's biggest standard-library refresh in years adds post-quantum TLS out of the box and trims small-allocation cost by up to 30%.
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encoding/json/v2 is finally in the box
A ground-up rewrite ships as encoding/json/v2 plus a low-level jsontext package — unmarshal is significantly faster and it now rejects invalid UTF-8 and duplicate keys by default. Need the old behavior? GOEXPERIMENT=nojsonv2 buys you time until 1.28, when v1 defaults are slated to go away.
Generic methods finally land
Methods can now declare their own type parameters, closing one of the largest gaps left open when generics arrived in Go 1.18. Standard-library APIs like math/rand/v2 already lean on it.
A portable SIMD package (experimental)
New simd and simd/archsimd packages expose vector-size-agnostic SIMD with real hardware acceleration — 128-bit on arm64/amd64/wasm, up to 512-bit on newer amd64. Build with GOEXPERIMENT=simd; it's the door to hand-tuned inference and vector-math kernels in pure Go.
Post-quantum crypto, no third-party lib
crypto/mldsa implements FIPS 204 ML-DSA, and TLS 1.3 gains MLDSA44/65/87 signatures plus MLKEM1024 hybrid key exchange. You can stand up post-quantum handshakes with only the standard library.
Small allocations up to 30% cheaper
Size-specialized malloc routines cut sub-80-byte allocation cost by up to 30% (about 1% overall in allocation-heavy code) for a ~60KB binary bump. Goroutine-leak detection also graduates to GA via runtime/pprof.