The ARMlite simulator is a web-based simulator of a 32-bit 'ARM-like' processor and Instruction Set Architecture (ISA), developed by Peter Higginson and Richard Pawson for teaching Computer Science (CS) principles and Assembly Language. It is targetted particularly towards the AQA A-level computing syllabus. It is exceptionally user-friendly and fast, and great fun to experiment with!
Free online student textbook on the topic:
[1] Richard Pawson (with Peter Higginson), Computer Science from the Metal Up - Assembly Language Programming, v1.0.0, 2020
https://peterhigginson.co.uk/ARMlite/Assembly%20Language%20-%20Student%20version.pdf
Online simulator for the ARMlite ISA here:
https://www.peterhigginson.co.uk/ARMlite/