jadx-rpc

A headless jadx engine for LLM agents. It answers structured questions about an APK, DEX or JAR over a plain command line, one JSON object per call.

$ jadx-rpc callers 'com.example.Payments.sign'
$ jadx-rpc members com.example.Payments
$ jadx-rpc class com.example.Payments --lines 40:120

Despite the name, there is no RPC in it. No daemon, no socket, no port, nothing running between calls. The name follows ghidra-rpc, which established <tool>-rpc as the headless component that lets an agent drive a decompiler. Ghidra needs a live process because its analysis exists only inside a JVM. jadx writes plain files, so this one does not, and a session is just a directory.

Why it exists

jadx has two shapes today and neither suits an autonomous agent. The GUI is built for a human reading code on a screen, and the plugins that expose it to a model need that GUI running. The command line tool is a batch decompiler with no memory between runs, so an agent that asks twenty questions pays the full parsing cost twenty times.

More to the point, jadx can already emit the two things that make Java analysis more than text search, and neither is usable as it stands: the symbol index arrives as a 35 MB single-line JSON file, and the call graph as a list of node and edge ids. No model can read either. Something has to query them. That is what this is.

If you only need to read and grep decompiled source, you do not need this at all. Run jadx -d out app.apk and use your normal tools. See docs/INTEGRATION.md for where that line falls.

Related MCP server: Apktool MCP Server

How it works

The session is a directory:

~/.local/state/jadx-rpc/<hash>/
  session.json      what was opened and how
  mapping.json      every class, method and field, original and displayed names
  res/              decoded resources, including AndroidManifest.xml
  src/              decompiled Java, written by the optional full export
  callgraph.json    resolved call edges
  cache/            classes decompiled on demand
  renames.mapping   recorded renames in Enigma format

Nothing runs between commands. Two agents can query the same session at once because they are only reading files, and a session survives a reboot.

What it costs

Measured on a 12 MB APK containing 10761 classes, with jadx 1.5.6 on an eight core desktop. Your numbers will scale with the size of the application.

The split is the point. Triage, symbol lookup and reading individual classes are all cheap, and the one expensive operation is opt in and runs in the background.

Install

jadx

jadx-rpc calls the jadx launcher, so install jadx first.

# any platform, from the release zip
curl -LO https://github.com/skylot/jadx/releases/download/v1.5.6/jadx-1.5.6.zip
mkdir -p /opt/jadx && unzip jadx-1.5.6.zip -d /opt/jadx
ln -s /opt/jadx/bin/jadx /opt/jadx/bin/jadx-gui ~/.local/bin/

# or from a package manager
brew install jadx                                  # macOS
sudo pacman -S jadx                                # Arch
flatpak install flathub com.github.skylot.jadx     # Flathub

jadx needs a 64 bit Java 11 or later. The zip ships both jadx and jadx-gui. jadx-rpc only uses jadx, the GUI is there when you want to look at the same target yourself.

jadx --version    # 1.5.1 or newer

If jadx is not on PATH, point JADX_BIN at the launcher.

The version is detected at open and reported by status. On an older jadx, callers and callees fail naming the version they need and nothing else is affected.

jadx-rpc

uv tool install git+https://github.com/AsherDLL/jadx-rpc

# or
pipx install git+https://github.com/AsherDLL/jadx-rpc

# or with the MCP server included
uv tool install "jadx-rpc[mcp] @ git+https://github.com/AsherDLL/jadx-rpc"

Python 3.10 or later. The base install has no dependencies at all, everything it needs is in the standard library.

jadx-rpc list     # expect {"ok": true, "result": {"sessions": [], "count": 0}}

Output is indented by default. The examples below use --compact, which prints one line, because that is easier to read in a page and easier to pipe.

Use

$ jadx-rpc open app.apk --export
{"ok": true, "result": {"id": "1781c62d0f3b", "classes": 19705, "methods": 117352,
                        "elapsed_s": 12.6, "export": "running"}}

--export starts the full decompile in the background. You do not have to wait for it, the commands below work immediately.

$ jadx-rpc entrypoints
{"ok": true, "result": {"package": "org.fdroid.fdroid", "target_sdk": "30",
                        "components": [...], "exported_count": 10, ...}}

$ jadx-rpc symbols 'crypt|token|secret'
{"ok": true, "result": {"scope": "app", "app_package_prefix": "org.fdroid",
                        "matched": 0, "matched_all_scopes": 2030,
                        "hidden_by_scope": 2030, ...}}

That result is the reason scoping exists. All 2030 hits were in bundled libraries and none in the application's own code, so unscoped the honest answer "this app does not do that itself" is buried under 2030 that say otherwise. --scope all widens, and nothing is ever hidden without being counted.

$ jadx-rpc members org.fdroid.fdroid.FDroidApp
$ jadx-rpc class org.fdroid.fdroid.FDroidApp --lines 1:80

Once jadx-rpc status reports the export ready:

$ jadx-rpc search 'javax\.crypto' --context 2
$ jadx-rpc strings '^https://'
$ jadx-rpc callers 'org.fdroid.fdroid.FDroidApp.onCreate'

Renaming obfuscated symbols, recorded now and applied in one pass later:

$ jadx-rpc rename class com.a.b.c com.example.PaymentHandler
$ jadx-rpc rename method 'com.a.b.c.d(Ljava/lang/String;)V' verifySignature
$ jadx-rpc renames
$ jadx-rpc reload

AGENTS.md has the full command reference, the cost of each command and a triage order that works. It is written to be read by a model, so point your agent at it. docs/INTEGRATION.md is the engineer-facing version: what the engine requires, what it guarantees, and how to map it onto a tool table.

Wiring it to an LLM

Three ways into the same functions. Pick whichever fits your stack.

Shell agents

Claude Code, Codex, Cursor, pi and anything else that can run a command. There is nothing to configure, the tool prints JSON. Give the agent the reference:

Read AGENTS.md in jadx-rpc, then triage app.apk and report every exported
component that reaches a crypto call.

MCP

claude mcp add jadx-rpc -- jadx-rpc mcp

or in a client configuration file:

{
  "mcpServers": {
    "jadx-rpc": {
      "command": "jadx-rpc",
      "args": ["mcp"],
      "env": {"JADX_RPC_TARGET": "/abs/path/to/app.apk"}
    }
  }
}

Twenty tools, one per command. jadx-rpc mcp --list-tools prints them without starting a server, and works on the base install. Serving needs the extra, pip install "jadx-rpc[mcp]".

Python, for ADK, LangChain and friends

Every command is an importable function that returns a dict and raises JadxRpcError on failure, so a framework can register it directly with no subprocess and no MCP hop.

from google.adk.agents import LlmAgent
import jadx_rpc

jadx_rpc.open_target("/abs/path/to/app.apk", export=True)

agent = LlmAgent(
    name="apk_triage",
    model="gemini-2.0-flash",
    instruction=open("AGENTS.md").read(),
    tools=[
        jadx_rpc.entrypoints,
        jadx_rpc.classes,
        jadx_rpc.symbols,
        jadx_rpc.members,
        jadx_rpc.decompile_class,
        jadx_rpc.search,
        jadx_rpc.callers,
    ],
)

The docstrings and type hints are the tool schemas, so nothing needs describing twice.

Environment

With exactly one session open, JADX_RPC_TARGET is optional. With several open and none named, commands fail and list the candidates rather than guessing.

Limits worth knowing

• open needs scratch space of roughly 25 times the input size, transiently. The index pass writes one JSON file per class beside the index it keeps, and jadx has no flag to suppress them. It refuses to start rather than fill the disk, and --index-tmp DIR points the scratch at a larger volume.

• Scoping uses the manifest package cut to two segments, so com.acme.app scopes to com.acme and catches sibling packages the same vendor owns. An app that ships its own code under an unrelated top-level package will see it counted as library code; --scope all is the escape, and hidden_by_scope is the signal.

• Field renames need a JVM descriptor, which the index does not carry. Build it from the declaration in the decompiled source. Class and method renames need nothing extra, members prints the exact string to pass back.

• jadx fails to decompile a small fraction of classes in most real applications. That is jadx behaving normally and the rest of the output is unaffected.

• Only local files are read. jadx-rpc does not fetch, upload or phone anywhere.

Development

git clone https://github.com/AsherDLL/jadx-rpc && cd jadx-rpc
uv venv && uv pip install -e . pytest
uv run pytest

The suite builds its own test jar with javac and runs real jadx against it, so it needs no network and no Android SDK. Tests skip cleanly when jadx or javac is missing.

License

GPL-3.0-or-later. See LICENSE.

jadx itself is a separate project under Apache-2.0. jadx-rpc runs it as an external program and does not include or link any of its code.