Cairo-Fuzzer is a tool designed for smart contract developers to assess security. It operates both independently and as a library.


  • Execute Cairo contracts.
  • Execute Starknet contracts.
  • Replay fuzzing corpus.
  • Minimize fuzzing corpus.
  • Load previous corpus.
  • Manage multiple arguments.
  • Utilize workspace architecture.
  • Import dictionaries.
  • Integrate Cairo-fuzzer as a library.


To use Cairo-fuzzer, run the following command:

cargo run --release -- --cores 3 --contract tests/fuzzinglabs.json --function "Fuzz_symbolic_execution"

This outputs:

For more usage information, follow our tutorial
CMDLINE (--help):

Usage: cairo-fuzzer [OPTIONS]

      --cores <CORES>              Set the number of threads to run [default: 1]
      --contract <CONTRACT>        Set the path of the JSON artifact to load [default: ]
      --function <FUNCTION>        Set the function to fuzz [default: ]
      --workspace <WORKSPACE>      Workspace of the fuzzer [default: fuzzer_workspace]
      --inputfolder <INPUTFOLDER>  Path to the inputs folder to load [default: ]
      --crashfolder <CRASHFOLDER>  Path to the crashes folder to load [default: ]
      --inputfile <INPUTFILE>      Path to the inputs file to load [default: ]
      --crashfile <CRASHFILE>      Path to the crashes file to load [default: ]
      --logs                       Enable fuzzer logs in file
      --seed <SEED>                Set a custom seed (only applicable for 1 core run)
      --run-time <RUN_TIME>        Number of seconds this fuzzing session will last
      --config <CONFIG>            Load config file
      --replay                     Replay the corpus folder
      --minimizer                  Minimize Corpora
  -h, --help                       Print help information