If you’re a Nextion user you might have run across the name TJC. TJC is Taojin Chi, a Chinese company that is somehow affiliated with Nextion and which Nextion generally denies any involvement with.
This is pretty hard to swallow, because their products look a little bit alike. For example, check out the 2.4" devices from each vendor:
Apart from the silkscreened logo and the first characters of the part number, these PCBs are
100% identical. The part numbers are the exact same, silkscreened part references the same, PCB traces the same, everything except the model is identical. (see below)
Now take a look at the editing software offered by each organization:
Apart from one being in Chinese and one in English, these too are identical. All features, buttons, etc are the same. When pressed, the Nextion support crew will tacitly acknowledge that TJC is the same product, but is supposed to only be sold in mainland China. TJC panels typically sell for less than half the price of the equivalent Nextion panel. Anyone selling TJC outside of mainland China is pretty quickly shutdown, presumably by the Nextion team to protect their profit margins.
The challenge with this is that the source (HMI) and compiled (TFT) files for each device are nearly identical but region-locked, so you cannot use a Nextion HMI in the TJC editor and vice versa, nor can you flash a Nextion TFT to a TJC panel, etc. After some basic investigation this appears to be due to security measures enabled on the STM32 processor which prevents simple hardware attacks from allowing the translation.
There have been tools created which tweaked the HMI or TFT files to allow cross-compatibility, but those tools no longer work on recent firmware releases. This is an ongoing area of research, which is explicitly protected in the US by interoperability exceptions outlined in the Digital Millennium Copyright Act (DMCA) under 17 U.S. Code § Section 1201 subsection (F) paragraph (1).
So that’s the deal - TJC is the Chinese Nextion, (officially) sold only in China, and the tools for programming it are only offered in Chinese language. The Nextion folks freak out whenever anyone brings it up, because they are busy collecting 100% extra $$$ whenever they can sell you a Nextion LCD instead of a TJC LCD.