r2flutter

r2flutter brings Dart and Flutter AOT awareness to radare2. It reads the snapshots embedded in release builds and turns their metadata into useful names, addresses, strings, classes, and references for reverse engineering. It is available both as the bin/r2flutter command-line tool and as an r2flutter command inside radare2.

Give it an extracted Android libapp.so, an Android directory containing one, an iOS .app bundle, or a direct AOT binary. AArch64 is the primary analysis target. The parser has in-tree layouts for Dart 2.10 through 3.12; see the support matrix for platform and version details.

What it can do

• Find Dart AOT snapshots in Flutter apps and supported standalone Dart containers.
• Recover snapshot headers, functions, classes, fields, type names, strings, ObjectPool values, instruction-table entries, and metadata references.
• Apply recovered names, flags, comments, classes, and code references to a radare2 session.
• Emit readable text, JSON for automation, or radare2 commands for importing into another session.
• Use Flutter's --save-obfuscation-map output to restore recovered names.

r2flutter is a metadata and analysis aid, not a Dart source-code decompiler. Recovery depends on what survived in the AOT snapshot, so some names and references are necessarily best effort.

Build and install

You need radare2 6.2.2 or newer (or a git build of 6.2.1), including its development headers, and r2 must be on PATH. The build obtains the required flags from r2 -H. Older radare2 versions lack the ic+ attribute support used to register class metadata and are rejected at compile time.

git clone https://github.com/trufae/r2flutter.git
cd r2flutter
make

The command-line tool is now ready at bin/r2flutter.

To install the radare2 plugin for your user account:

make user-install

For a system-wide command-line tool and plugin, build the plugin first and then use the usual install prefix:

make r2
sudo make install

First look at an app

Start with the snapshot header. It confirms that r2flutter found a Dart AOT image and shows the detected Dart profile:

bin/r2flutter -H path/to/libapp.so

Then try a small, practical extraction:

# Recovered Dart function entrypoints and names
bin/r2flutter -f path/to/libapp.so

# A compact JSON header, useful for scripts
bin/r2flutter -jH path/to/libapp.so

# The first 20 instruction-table entries
bin/r2flutter -l 20 -i path/to/libapp.so

Directory and bundle inputs work too. For example, pass an Android directory containing libapp.so, or an iOS Runner.app bundle directly.

After make user-install, open the same binary in radare2 and apply the Dart metadata to the analysis session:

r2 -q path/to/libapp.so
> r2flutter -AAA
> afl~method

-AAA is the Dart-aware analysis pass. For a concise list of every action and output modifier, run bin/r2flutter -h or r2flutter -h inside radare2.

Learn more

• Support matrix — accepted containers, platform scope, and Dart layout coverage.
• AuthPass walkthrough — a complete iOS AOT analysis example using recovered method names in radare2.
• ObjectPool internals and instruction-table entries — the two central structures behind function and constant recovery.
• Strings and cross references — what can be recovered and how reliable each result is.
• Flutter obfuscation maps — restore names from a map produced during a Flutter build.

Related projects

• Dart SDK
• blutter
• unflutter
• reFlutter

Released under the MIT license.