https://felixselter.github.io/MurmelRechner/
Load your code
Save your code
Generate a flowchart
Format your code
Add a register/marble store
remove the last register/marble store
Execute your entire code
Execute this line. The current position is indicated by this pointer 
Click this to stop your program if youre stuck in an infinite loop
Enable the collaboration mode
Enter the fullscreen mode
Click the id to get a link so you can invite others
Becomes
It can automatically generate a flowchart from your code
Enable the collaboration mode to work with others at the same time
Example multiplication code
tst 1
--jmp 4
hlt
dec 1
tst 2
--jmp 8
jmp 12
dec 2
inc 3
inc 4
jmp 5
tst 3
--jmp 15
jmp 1
dec 3
inc 2
jmp 12