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To flutter: to move in quick, irregular motions, to beat rapidly, to be agitated.
Doldrums: a period of stagnation.

Doldrums is a reverse engineering tool for Flutter apps targetting Android. Concretely, it is a parser and information extractor for the Flutter/Dart Android binary, conventionally named, for all Dart version 2.10 releases. When run, it outputs a full dump of all classes present in the isolate snapshot.

The tool is currently in beta, and missing some deserialization routines and class information. If it does not work out-of-the-box, please let me know.


Doldrums requires pyelftools to parse the ELF format. You can install it with

pip3 install pyelftools


To use, simply run the following command, substituting for the appropriate binary, and output for the desired output file. Note that the verbose option only works for Dart snapshot v2.12.

python3 src/ [-v] output

The expected output is a dump of all classes, in the following format:

class MyApp extends StatelessWidget {
    Widget build(DynamicType, DynamicType) {
        Code at absolute offset: 0xec85c

    String myPrint(DynamicType, DynamicType) {
        Code at absolute offset: 0xeca80

The absolute code offset indicates the offset into the file where the native function may be found.

Reading material

For a detailed write-up on the format, please check my blog post.

Related works

darter is a fully implemented and fully tested parser for Dart version 2.5 releases.


If you'd like to help the project, consider making a pull request, or donating to

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