This is the first preview of v4.
v4 is a ground-up redesign: more than twice the performance, stronger security by default, full Native AOT support, and many new features, including support for C# 14 union types.
The basic API shape is unchanged, and v4 is feature-compatible and wire-compatible with v3 (v3 and v4 read each other’s output). It does, however, contain many breaking changes; see the v4 README and its “Migrating from v3” section before upgrading.
Please report any problems in the Issues.