Machine Coders are robotic creatures designed to destroy intruders inside a computer system. They appear in TMHT Adventures comics by Fleetway Publications.
After Shredder and Krang managed to hack into New York’s financial computer system, the Turtles set out to stop their evil plans. April O'Neil arranges for them to have some privacy inside the Wall Street Stock Exchange computer room. Donatello rigs up a system that allows the Turtle's minds to enter the computer to find the evil duo. Almost as soon as they've entered the computer system, they are set upon by what Don calls 'Machine Coders', robotic creatures designed to destroy intruders. Nearly as tall the the Turtles, they have metal arms with sharp sheers on the end, round metal bodies, and large jaws of jagged steel.
As Don baps one with his staff, he adds that unfortunately, the Coders don’t realize they are there to help. Machine Coders advance on the Turtles, who begin battling the robots. Raph comments on how quickly they move and when Leo tries to use his katana on one, he learns the hard way that they are also armor plated. When the Turtles’ tactics don’t slow the robots down, Leo asks Don for ideas on getting out of there. Don says to jump, since being in a computer world means the laws of reality don’t apply. They hop down onto an energy wave, which takes them through the computer system like a moving sidewalk and away from the Coders
After locating Shredder and Krang, and defeating the Computer Bytes the villains set on them, Shredder yells at the Turtles for making too much noise. This is because the sound has attracted the Machine Coders, and since they are not something created by Krang or Shredder, they will attack them too. Leo tells his brothers to think quick to try to see a way out of this. Don suddenly has an idea and says they can make themselves disappear. He explains that they are in a mind control link with the computer, so their bodies are made of mental energy. They can use their ninja powers of concentration to make themselves disappear. By becoming invisible, the machine coders won’t get them. Don demonstrates and is quickly invisible, so Leo tells the others to follow his example. As a ninja, Shredder is also able to accomplish invisibility, but Krang cannot. He yells at Shredder and pleads for help, managing to bother Shredder enough to break his concentration. The last the Turtles see of the evil pair, they are being chased by the Machine Coders.