I can program the board using the 'debug' menu. I want to release the executable to production. How do I program the board outside the IDE? I could not find anything in the manual. I am using an LPC4537.
FlashMagic does support ISP.
Depending on how you configure your boot pins you normally automatically get an empty chip to wait in the ROM monitor program for FlashMagic or other program to connect and perform ISP. If using an UART, then all you need is a RS232-to-TTL of suitable voltage level. Or maybe a USB-to-3V3 logic-level RS232 cable for maybe $15.
So FlashMagic works both for low volume 1-10 boards or high volume. And is free for development but requires a not too expensive license for factory use - or for field programming. And the licensed versions has scripting support.
But you reall have quite a number of options besides JTAG with that specific LPC4357.
It is even possible to send a programming cable to a customer and have them download FlashMagic and pretend to be developer if you want them to do a full factory reprogramming of a device, i.e. replace everything including the boot loader.