hi ,
Pavan is right that as such you cann't find any tool which is 100% free. But ya you can try for Demo/student version of the Tool. Cadence usually provide the student version of several tool. You can try in their website.
Apart of this please cehck the following website. I am not sure how mush it will help you but you can try.
- alliance
Index of /pub/alliance/distribution/5.0
- magic
Magic
- electric
ftp://ftp.gnu.org/pub/gnu/electric/
- **broken link removed**