Cloud-powered fuzzing infrastructure that runs Echidna, Medusa, Halmos, and Foundry — 12,500+ campaigns and counting.
Fuzzing generates random inputs and transaction sequences to test your smart contracts for unexpected behavior. Stateful fuzzing (what Recon specializes in) maintains contract state across sequences, enabling it to find complex multi-step bugs that simpler testing approaches miss entirely.
We use the right tool for each job. Here's how the major smart contract fuzzers compare.
| Tool | Type | Strengths | Best For |
|---|---|---|---|
| Echidna | Property-based fuzzer | Mature, corpus-driven, grammar-based input generation | Complex stateful protocols, production-grade invariant suites |
| Medusa | Property-based fuzzer | Parallel execution, fast coverage, Go-based | Large codebases that benefit from parallelism |
| Halmos | Symbolic execution | Mathematical completeness, bounded model checking | Arithmetic properties, formal guarantees for bounded inputs |
| Foundry Fuzz | Stateless fuzzer | Fast iteration, integrated with Foundry workflow | Quick property checks, unit-test-adjacent fuzzing |
Recon Pro removes the infrastructure burden from fuzzing. Queue campaigns, monitor progress, view coverage reports, and share results — all from the browser. No Docker setup, no cloud provisioning, no DevOps overhead. We've run over 12,500 cloud fuzzing campaigns for teams building on Ethereum, L2s, and beyond.
Stateless fuzzing tests individual functions with random inputs. Stateful fuzzing chains multiple function calls together, maintaining contract state between calls — mimicking how contracts are actually used in production. This is critical for finding bugs that only appear after specific sequences of actions, like the multi-step exploits behind most major DeFi hacks.
Smart contract fuzzing automatically generates random transaction sequences to test your contracts for vulnerabilities. It's a form of property-based testing where stateful fuzzing maintains state across calls, finding complex bugs that unit tests and manual review miss.
Stateless fuzzing tests individual functions in isolation with random inputs. Stateful fuzzing chains multiple calls together, maintaining contract state — this finds multi-step exploits that stateless fuzzing can't reach.
Yes. Recon Pro provides cloud fuzzing infrastructure — queue campaigns, view results, and share with your team without managing any infrastructure. We've run 12,500+ cloud campaigns.
Fuzzing is faster to set up and more practical for real-world codebases. Formal verification provides mathematical guarantees but is expensive, slow, and breaks when code changes. Most teams get better ROI from fuzzing. Tools like Halmos offer a middle ground with bounded symbolic execution.
With a well-written invariant test suite, we typically achieve 90-100% line coverage and high branch coverage. Recon Pro provides detailed coverage reports so you can see exactly what's been tested.
Talk to our fuzzing engineers or try Recon Pro.
Send Audit RequestThorough manual review combined with invariant testing — the most rigorous approach to smart contract security available today.
DeFi-native security researchers who understand composability risks, economic attacks, and protocol-specific vulnerability patterns.
We write the invariant tests that catch the bugs your manual audit missed — then hand you a test suite you can run forever.
Deep Solidity expertise combined with automated invariant testing — covering every EVM chain from Ethereum to L2s.