Lastime I used mathcloud it worked beautifully, several months ago.
Now when I press the process button it frequently fails to produce results, even with simple equations, but sometimes it does.
Is there a backend server not worker?
I input in MathML to get SVG results I can use in ePub where many viewers still do not render MathML.
Sometimes telling it my input is ascii and then switching back to mathml works but that may have been coincidence.
Example of simplicity it sometimes chokes producing no output or errors but sometimes renders:
<math>
<mi>L</mi>
<mo>=</mo>
<mfrac>
<mi>c</mi>
<mi>f</mi>
</mfrac>
</math>