Self-serve is nice, though IPv4.online notes that full self-serve browsing is still on the way, so for now you look at the live snapshot and request a quote. They have a documentation section and BYOIP pages for AWS, Google Cloud, Azure and Cloudflare, which I found useful. When you’re ready, ask exactly what they need for the LOA. For a first IPv4 deal I’d talk to them anyway, to avoid surprises. Documentation matters more than the sales deck, so read how LOAs and BYOIP are explained before you commit. If the docs are thin, that’s a signal. Ask for a sample LOA to share with your upstream. Also check how fast they reply: if answers take days before you’ve paid, support will be slow afterwards.