Wikipedia
SASM
SASM (SimpleASM) — a simple Open Source crossplatform integrated development environment for NASM, MASM, GAS and FASM assembly languages with syntax highlighting and debugger.
SASM makes it easy to develop and run programs written in assembly language. The program works out of the box and is great for beginners to learn assembly language.
Licensed under the GNU GPL v3.0. Based on the Qt.
It was created by the programmer Dmitriy Manushin (Dman95).