Keystone — multi-architecture assembler library
Keystone (keystone-engine/keystone) is a multi-architecture assembler library. Release 0.9.2 (2020-06-21 UTC) remained the latest GitHub Release on 2026-10-24. License is GPL-2.0. Use it to encode instructions for tooling that modifies binaries you are authorized to change.
Snapshot
| Field | Value |
|---|---|
| License | GPL-2.0 |
| Latest checked | 0.9.2 (2020-06-21 UTC; still latest Release object 2026-10-24) |
| Job | Multi-arch assembly → machine code (library) |
| Stars (order of magnitude) | ~2.7k on GitHub (counts change daily) |
| Peer | Capstone for the decode direction |
When Keystone fits
- You are writing a patcher or fuzzer mutator for owned/lab binaries.
- An open-source project already links Keystone and you are extending it under authorization.
- You need encode bindings alongside Capstone decode in one toolkit.
When to prefer something else
| Need | Prefer |
|---|---|
| Interactive patching GUI | Ghidra / Cutter |
| Fast x86/x64 decode only | Zydis |
| Full RE suite | Ghidra / Binary Ninja / IDA (licensed) |
Legal note
Assembling bytes does not authorize modifying arbitrary third-party software. Keep patches inside policy.
- Use Keystone when you need a library to encode instructions.
- Pair with Capstone for decode in the same pipeline.
- Prefer interactive suites when you are still learning RE basics.
For legal, authorized and educational use only.
FAQ
What is Keystone?
Keystone is a multi-architecture assembler framework — you give it assembly text and it returns machine code bytes. It is commonly paired with Capstone (disassembly) in custom tooling.
Which version is cited?
0.9.2 published 2020-06-21 UTC on keystone-engine/keystone Releases (still the latest GitHub Release object on 2026-10-24).
What license applies?
GitHub reports GPL-2.0 for keystone-engine/keystone (checked 2026-10-24). Confirm COPYING/LICENSE in the tree you pin.
Capstone or Keystone?
Capstone decodes machine code to assembly; Keystone encodes assembly to machine code. Many pipelines use both.
Does this teach patching commercial DRM?
No. Encode only patches for binaries you own or may modify under authorization.