Simple IPAM for quickly see reserved/available IP blocks

Hello guys,

At my current client, we are using a simple Excel spreadsheet to see our used/unused subnets. We started with a single line, our /8, that we split into 2 lines of /9, etc, etc... We just split what we need, and put the rest in grey color, to indicate unused blocks. We have a tab for each VRF.

Now, even thought this is pretty rare, we do make mistakes. Splitting let's say a /22 into /25 might ends up with a disappearing subnet, or miscalculated and overlapping subnets...

I've looked at multiple IPAM solutions. It looks like they do a thousand things, but not what I want. I don't want a 100K$/y clusterf*ck solution that I will use at 5%. I don't want to link it to my DHCP, nor my DNS, nor whatever. I just want multiple tabs for each of my VRFs with what I've used so far from my /8, and what is free.

If my Excel could pop an error for overlapping networks or do the splitting for me, that would be enough for me.

Do you guys have good solutions for that ?

Thanks !