Cold-chain shipping — which vendors use proper temperature control?

Taking the question as asked, rather than the general version of it. The useful checklist is about verifiability rather than presentation. Independent test results commissioned by buyers rather than by the seller, consistency across multiple batches over time rather than one flattering report, a physical address and a company registration that resolve, batch and lot numbers on the actual labelling, and a shipping practice that matches what the material needs. Everything a good-looking website provides is cheap to fake; none of the items above are.

LabKate said:

The useful checklist is about verifiability rather than presentation.

Agreed, with a caveat about community reputation: it is a lagging indicator. Reports arrive weeks after orders, so a supplier can look excellent for a month after quality has already changed.

Ask again with the specifics and you will get a better answer than this one.

alex_tucson said:

One order arrived in nine days, one was held at the border for a fortnight, and one came back with a seizure notice.

Right, and one flattering data point from a group buy is not consistency. Consistency means separate batches, separately commissioned, over months.

Adding the clinical framing, because it changes how the question reads.

My experience ordering cross-border ordering internationally: I've ordered from an Australian compounder. Customs can be hit or miss.

Shipping time: 5-10 days
Customs clearance: was seized once, reshipped free
Quality: Janoshik tested at 97.0% purity

International ordering adds complexity but can save 60-80% compared to US prices. Research your country's import laws first.