Tcl/Tk 9.1.0 is now available, according to the official Tcl Developer Xchange site at tcl-lang.org. Released on September 29, 2026, it is the current development work on Tcl and Tk, adding new features and interfaces to the foundation laid by Tcl/Tk 9.0. The project says it is aiming toward stable releases in September 2026.
For developers and founders in hacker circles, this is more than a routine version bump. Tcl/Tk has powered everything from network tools and test automation to desktop GUIs for decades, and the 9.x line represents its biggest modernization push in years.
What's new in Tcl/Tk 9.1.0
The release builds directly on Tcl/Tk 9.0, extending the core language and the Tk toolkit with new features and interfaces. The project positions 9.1.0 as development work rather than a final stable release, with stable versions targeted for September 2026. Source releases are available for download from the official site.
Because the changelog details are not included in the source, developers should check the official release notes for the full list of additions and any compatibility notes before upgrading production systems.
- Version: Tcl/Tk 9.1.0
- Release date: September 29, 2026
- Status: current development work toward stable releases in September 2026
- Focus: new features and interfaces on top of Tcl/Tk 9.0
