hermes-decomp v0.2.2 — A powerful decompiler that lets you reverse-engineer React Native mobile apps by converting their compiled Hermes bytecode (.hbc) files back into readable JavaScript.

Hermes Bytecode Decompiler

Rust decompiler for Hermes bytecode (.hbc), the JS engine behind React Native. Supports HBC 40 to 99.

Install

Pre-built binaries (Linux / macOS / Windows) from Releases or Actions:

Asset suffix	Platform
`linux-x86_64` / `linux-arm64`	Linux
`macos-arm64` / `macos-x86_64`	macOS
`windows-x86_64`	Windows

Archives include hermes-decomp and hermes-mcp. Verify: shasum -a 256 -c SHA256SUMS.

hermes-decomp update --check      # or --install / --version v0.1.7

From source (Rust 1.70+):

git clone https://github.com/SymbioticSec/hermes-decomp.git
cd hermes-decomp && cargo build --release
# → target/release/hermes-decomp  target/release/hermes-mcp

Quick start

hermes-decomp info app.hbc
hermes-decomp disasm app.hbc --function 5 --info --show-offsets
hermes-decomp decompile app.hbc -o out.js          # progress on stderr
hermes-decomp decompile app.hbc --function 42
hermes-decomp tui app.hbc
hermes-decomp xref app.hbc --query "loginWithToken"

Disassembly Example

Decompilation Example

What it does

Area	Commands (highlights)
Read	`info`, `disasm`, `decompile`, `tui`, `extract`, `modules`, `deps`
Analyze	`xref`, `callgraph`, `graphviz`, `closures`, `debug`, `dump`, `bin-diff`
RE helpers	`secrets`, `frida-hooks`
Write (bytecode only)	`emit-hasm`, `asm`, `asm-check`, `patch-string`, `patch-function`, `inject-stub`, `create`

Full flags and examples → docs/USAGE.md.

Notes:

Full-bundle decompile uses an on-disk .hdcache for fast reloads. Pass --no-cache to force.
Write tools patch bytecode / HASM. They do not recompile decompiled JavaScript.
decompile -o … prints pipeline stages on stderr.

MCP & library

MCP server (hermes-mcp) for AI assistants → docs/MCP.md
Config template: mcp-config.example.json
Rust crate hbc-decomp → docs/LIBRARY.md

cargo build --release -p hbc-decomp-mcp

Contributing

See CONTRIBUTING.md. Please open an issue before a PR.

cargo build --release --workspace && cargo test --workspace

Resources

Hermes Engine · React Native

License

MIT. See LICENSE.