What is the difference between OASIS and GDS?

OASIS files are much smaller compared to GDSII. When we started working on advanced nodes like 7nm and 5nm, the GDS files were becoming huge and difficult to handle. That’s when we switched to OASIS, and it really helped with faster load times and tool performance.

Yeah, OASIS is definitely more efficient. One thing you’ll find interesting is that OASIS supports compression and repetition better than GDS. So if your design has a lot of repeated cells or patterns, OASIS will store them smartly without duplicating everything. We saved a lot of disk space when we moved from GDS to OASIS in our tapeouts.

I agree with both of you, but I'd just add that GDS is still more widely used in older design flows. If you're working with legacy tools or IPs, you’ll often get GDSII format. But if you're in a modern flow or dealing with huge designs, especially with foundries, they’ll usually ask for OASIS. So you might end up converting between both depending on the flow you follow.