Online Tool for Assembly ↔ Opcode Conversion + Emulation

Hey everyone!

During my recent reverse engineering sessions, I found myself needing a quick and convenient way to convert assembly code to opcodes and vice versa. While great libraries like Capstone and Keystone exist (and even have JavaScript bindings), I couldn’t find a lightweight online tool that made this workflow smooth and fast - especially one that made copying the generated opcodes easy (there are official demos of Capstone.js and Keystone.js yet I found them to be little bit buggy).

So, I decided to build one!

What it does:

• Converts assembly ↔ opcodes using Keystone.js and Capstone.js.
• Supports popular architectures: x86, ARM, ARM64, MIPS, SPARC, and more.
• Includes a built-in emulator using Unicorn.js to trace register states after each instruction.

Notes:

• There are some differences in supported architectures between the assembler/disassembler and the emulator—this is due to varying support across the underlying libraries.
• Yes, I know Godbolt exists, but it’s not ideal for quickly copying opcodes.

I’d love for you to try it out and share any feedback or feature ideas!