• Cold/hot wallet split — never keep more than a small operational float in hot wallets

• Multi-sig withdrawal approval — single-key custody is how most 2024-25 hacks happened

• Third-party smart contract audit — before mainnet, not after a scare

• Rate-limited API + DDoS protection — matching engines get hammered during volatile sessions

• Insurance fund / SAFU-style reserve — rebuilds user trust fast if something does go wrong

• Regular penetration testing — quarterly minimum once you're handling real volume

Most teams underestimate how much of the launch budget should go here versus UI/marketing. If you're scoping a build, it's worth studying how an established crypto exchange development service structures this stack before finalizing your own architecture saved me from a few rookie mistakes early on.

What's everyone else prioritizing security-wise before going live anything on this list you'd rank differently?