Feel free to browse the site to see what filter tools are available. Here we deal with passive filter: Butterworth, Chebychev, Bessel, Elliptic are the most common ones. There is also a dedicated site for microwave filters.
It is possible save a single design for up to 24hrs, so repeat analysis perfection can be carried out in that period. However, thie space allocated for this function is limited and will be allocated on a first come, first served basis ie: a design could be ersed before the nominal 24hrs.
Sponsorship welcomed from component manufactures etc.