This page collects information about the serprog protocol and the programmers implementing it.
See serprog-protocol.txt in the source tree. It is designed to be compact and allow efficient storage in limited memory of programmer devices.
AVR flasher by Urja Rannikko
The Prototype RS232 AVR parallel flash programmer of Urja Rannikko was the first implementation of the serprog protocol.
The source code can be found here.
AVR flasher by eightdot
Arduino Mega flasher by fritz
InSystemFlasher by Juhana Helovuo
atmegaXXu2-flasher by Stefan Tauner
Like the InSystemFlasher this one uses LUFA on an AVR microcontroller to tunnel the serial data over USB.
Various Arduino based flashers
For detailed instructions on how to use different Arduino models to access SPI flash chips see Serprog/Arduino flasher.
The source can be found here
Teensy 3.1 SPI + LPC/FWH Flasher
serprog-stm32vcp by Chi Zhang
The most powerful serprog-based programmer is built upon an ARM Cortex-M3 (STM32F103) featuring up to 36 MHz SPI clock. See his github page for further details, source code etc.