Chicken Scheme 6.0 introduces R7RS compliance across core libraries, enhances Unicode support via UTF-8 string handling, and replaces blob modules with bytevector operations. Key changes include UTF-8/Latin-1 file encoding support, process-object handling, and improved file-locking with `flock(2)`. Module reorganizations move primitives to R7RS standards, remove deprecated features like `#${...}` syntax, and add binary port creation. Security fixes address CVE-2022-45145, neutralizing egg metadata risks. Build systems now use `configure` scripts, require POSIX shells on Windows, and support `zig cc` compilation.

The update emphasizes bytevector operations over strings, with `read-bytevector` replacing older methods. Process management shifts to object-oriented models, and symbol escaping rules tighten. Security hardens runtime option parsing, blocking post-`-:` arguments. Tools like `csc` now handle spaced paths without quotes, while `chicken-install` locks cache directories during egg installation.

Notable removals include `srfi-0` aliases and `#ci` read syntax. New features include `include-ci`, `number-vector-data`, and expanded `define-library` capabilities. Complex number handling in `make-rectangular` and `string->number` improves precision. Compiler optimizations enable closure reuse/sharing via `-merge-reusable-closures` and `-merge-shareable-closures`.