The Unicorn emulator framework, now available for JavaScript.

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Before going to the Installation / Tutorial panels below, you might want to see Unicorn.js in action. Below you have simple demos, showing realtime client-side emulation of foreign architectures thanks to Unicorn.js, as well as Capstone.js and Keystone.js to assemble/disassemble instructions.



Unicorn.js is a port of the Unicorn emulator framework for JavaScript, done with Emscripten. It's released as a 19 MB JavaScript file supporting the architectures: ARM, ARM64, M68K, MIPS, SPARC, and x86. Alternatively, per-platform Unicorn.js releases are also available here. Follow the Readme to build Unicorn.js manually.

Unicorn is a lightweight multi-architecture CPU emulator framework originally developed by Nguyen Anh Quynh et al. and released under GPLv2.


To use the Unicorn.js in your web application, download and include it with:

<script src="unicorn.min.js"></script>

or install it through the Bower command:

bower install unicornjs


var addr = 0x10000;
var code = [
  0x37, 0x00, 0xA0, 0xE3,  // mov r0, #0x37
  0x03, 0x10, 0x42, 0xE0,  // sub r1, r2, r3

// Initialize engine
var e = new uc.Unicorn(uc.ARCH_ARM, uc.MODE_ARM);

// Write registers and memory
e.reg_write_i32(uc.ARM_REG_R2, 0x456);
e.reg_write_i32(uc.ARM_REG_R3, 0x123);
e.mem_map(addr, 4*1024, uc.PROT_ALL);
e.mem_write(addr, code)

// Start emulator
var begin = addr;
var until = addr + code.length;
e.emu_start(begin, until, 0, 0);

// Read registers
var r0 = e.reg_read_i32(uc.ARM_REG_R0);  // 0x37
var r1 = e.reg_read_i32(uc.ARM_REG_R1);  // 0x333