Free open-source tool: downgrade GDL objects (.gsm) to older Archicad versions

Jochen Suehlo — Tue, 30 Jun 2026 20:57:01 GMT

Hi all,

There have been frequent enquiries here on the forum about whether and how it is possible to convert GDL objects from a higher version of Archicad to a lower one.

So I built a simple, easy-to-use GUI tool for exactly that, and I'm sharing it for free.

GDL-Downgrader (free, open-source, MIT license)

What it does:

Converts .gsm objects from a newer to an older Archicad version
Built on Graphisoft's own LP_XMLConverter (no black box)
Auto-detects the source version from the object header and finds your
installed converters automatically
Command safety check: warns about GDL commands that don't yet exist in the
target version
Keeps password protection (re-encrypts after downgrade)
Recursive folder processing, keeps the original structure
Bilingual UI (EN/DE), runs fully offline, no external services

macOS (Apple Silicon) and Windows downloads, plus full details here:
https://www.b-prisma.de/develop/gdl-downgrader/

It's free and open source — feedback and bug reports are very welcome.

topic Free open-source tool: downgrade GDL objects (.gsm) to older Archicad versions in GDL

Free open-source tool: downgrade GDL objects (.gsm) to older Archicad versions