Latest Release: Tcl/Tk 9.0.2 was released on Jul 2, 2025. It's the latest major release with new capabilities and incompatibilities with Tcl/Tk 8.

• Download: Download Tcl/Tk 9.0.2 Source Releases

Tcl 9.0 Highlights:

• 64-bit capacity for data values larger than 2Gb.
• Unicode and encodings support including full codepoint range, added encodings, and encoding profiles.
• Zip filesystems can be mounted as filesystems.
• Attached archives enable starkit-style app deployment.
• New notifiers using epoll or kqueue.
• Many new commands and features.

Important Incompatibilities in Tcl 9.0:

• Namespace varname resolution is in the current namespace, not global.
• I/O malencoding now raises an error by default.
• Tilde (~) in pathnames is no longer interpreted as the home directory.
• tcl_precision no longer affects number formatting.

Tk 9.0 Highlights:

• Access to OS facilities like notifications, print, and tray systems.
• Scalable Vector Graphics with partial support in images and extensive use in widgets and themes.
• Full access to image metadata and alpha channel.
• Improvements in platform features and conventions including two-finger gesture support.

Summary of Changes for Tcl:

• Major features include 64-bit capacity, internationalization, zip filesystems, etc.
• Notable incompatibilities in various aspects like namespace resolution, I/O, etc.
• Incompatibilities in the C public interface.
• New commands like array default, chan isbinary, etc.
• New command options.
• Improvements in numbers handling.
• TclOO facilities like private and class variables.

Summary of Changes for Tk:

• Many improvements in using platform features and conventions.
• New commands and options like tk sysnotify, tk systray, etc.
• Widget options like new ttk::progressbar option and more.
• Improved widget appearance like ttk::notebook with nondefault tab positions.
• Partial SVG support and access to image metadata.