Tonne Software

Download page for
Elsie the filter design program

When Elsie is run, it normally operates in the Student mode. If it finds the purchased key, it automatically and transparently upgrades itself up to the full Professional mode with no effort on the part of the user.

By purchasing the key - priced at only US$ 95 - the program operates in the Professional mode.

The key you purchase unlocks the free Student edition so that it operates as the full Professional edition, even after installing an updated version.

The keyless Student Edition is designed for the student, hobbyist or light industrial user. It can handle fewer network components than the full Professional Edition. This has been done to encourage purchasing the key to unlock the program up to the Professional level. And some features in the Professional Edition are not available in the Student Edition to further encourage purchase of the upgrading key.

Elsie is supplied as self-extracting 32-bit Windows® installation file of about 6MB.

The current version of Elsie is 2.86 - get it here:

(The manual was current as of version 2.50 and so is in need of upgrading but is nevertheless still quite useful.)

You may go to to check a given executable file. They check executables using 55 different scanners for viruses. All of our programs and install files come up clean!