here is a link to a mdi2, which seems to be the "easiest" to use. it is a clone but should accept the bosch software updates to work with techline for programming.
Find many great new & used options and get the best deals for MDI2 WIFI multiple diagnostic interface diagnosis programming scanner Hardware.. at the best online prices at eBay! Free shipping for many products!
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then there is the vcx nano which can be a royal pita to get up and running, but it also comes with tech2win and gds2 software both of which are hacked so you don't have to pay exhorbirant fee's (for diagnostic purposes) and getting it to work for techline programming can be very hard as the vcx will need to be updated often it seems to be a battle between gm and the hackers, gm fixing loopholes and the hackers finding new ones. if you get a vcx I recomend use a laptop dedicated to just using it for the car because you have to turn all the windows security off to install the software because it is hacked and windows see's it as a virus which it most likely also has but that's the only way to get it installed because the windows files have to be changed there is no other way around it. so just don't be signing into your bank or something if you have that installed lol
then you get into more pricier stuff like a mongoose plus, autemaxi flash, etc those are in the $500+ range they are more legit type products but may not be worth the extra cost, just depends on your needs
or a autel maxiflash