Game Boy flash cartridges

Re-writeable Game Boy cartridges

inside gadgets flash carts:
The top recommendation! Different models from 10 to 58$ available.
With or without USB, with SRAM or FRAM, with and without RTC support, even a model with custom boot logo is available. RAM size from 32KB up to 4MB. Besides inside gadgets offers the best cart-reader/writer, in my opinion!
https://www.insidegadgets.com/

krikzz Everdrive GB:
The most known flashcarts of current times. Usage via Mirco-SD card. Different versions from 39 to 129$.
The newest model supports RTC (real time clock). Caution! Version X3 and older versions are not fully compatible with LSDJ or the Game Boy Camera! X5 and X7 can run LSDJ without any issues.
https://krikzz.com/store/

Benn Venn’s El Cheapo SD:
Different cartridges available in a variable price range. Mostly only available temporarily or through preorder.
Usage via Micro-SD or via cart-reader/writer, depends on cartridge.
https://bennvenn.myshopify.com/

EZ Flash jr:
Available at different sellers. Cartrdige for usage with Micro-SD, similar to Everdrive GB.
https://www.ezflash.cn/product/ezflash-junior/

EMS GB USB 64m:
Probably the most used cartridge within the last 10 years in the chiptune scene.
Isn’t produced any longer, but still available rarely.
Optimal usage via USB under Windows XP or with the help of a cart-reader/writer.
For Windows 7, 10 and Linux users, I recommend using the software called “qart” instead of the original software.

Drag’n Derp:
Back in the days the first cartridge with FRAM support! Not available anymore.
Best use under Windows 7 or with a cart-reader/writer.
http://derpcart.com/buy.html

Other:
There are several other flash cartridge DIY- and hobby-projects.
For example jrodrigos flash mermory adapter.
Listing them all would be way to much though.

Definition:
USB – USB port directly on the cartridge itself.
SD – Micro SD slot on the cartridge.
Reader/Writer – Specific hardware to read from, and write onto Game Boy cartdriges.
SRAM – storage type, needs a battery (coin cell) within the cartrdige to be able to save.
FRAM – storage type, doesn’t need a battery to save.
RTC – real time clock, is only use by a few specific games.
Custom boot logo – own custom logo can be used, instead of the typical Ninendo logo while starting.

*The whole article was written with Windows systems in mind.