Best bulk uploader for print on demand?

I only know of podlify. I'm about to take the premium account.​

Has anyone tested it before ? Is it worth it ? (I have 1500 tshirt)

Here's tehir description :

"Simplify Print On Demand.​

PODlify automates the upload, amplifies marketing and enables sustainable monetizing of designs across Redbubble, Society6, Teespring, Teepublic, Threadless Spreadshirt, Cafepress and Spreadshirt.co.uk with more marketplaces coming soon."​

Apparently they're dead... any competitor?

PODlify going OFFline :-(​

Unfortunately we will be stopping our services for reasons beyond our control. We loved serving our amazing community of creators, but time has come for us to say goodbye. Website will stay online till 7th March for you to delete data, if needed. Once we go offline, all data will be completely destroyed.
Effective immidiately, our upload and verification systems are not processing any data anymore.More Options
If you are a PRO or PREMIUM subscriber, we will be issuing you a refund for last month.

anyone have any experience with podturbo?

So basically, this tool just uploads the design.

Does it have some sort of automated design "conversion" between the different POD platforms?

You've listed Redbubble, Society6, Teespring, and others.

It's my understanding that they have different formats.

Or, is there some sort of standard format that these sites use?

It would be great if such a tool has a standard design input and it would just make the necessary adjustments while it automatically shares to those different sites.

I see this doing quite well for purely text-based t-shirt designs.

You can use lazymerch there are all platforms and a good Research Tool.