OSS-Fuzz vs syzkaller

OSS-Fuzz9.2Visit Ssyzkaller8.1Visit

Higher score OSS-Fuzz #2 in Fuzz Testing Software 9.2/10 Free plan Free plan✓ 3 of 3 features Visit OSS-Fuzz

vs

S syzkaller #8 in Fuzz Testing Software 8.1/10 Open source ✓ 3 of 3 features Visit syzkaller

• OSS-Fuzz fits best

  Free continuous fuzzing for open-source projects

• syzkaller fits best

  Operating-system kernel fuzzing

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Side by side

Feature	OSS-Fuzz 9.2/10 Visit ↗	Ssyzkaller 8.1/10 Visit ↗
At a glance
Editor score	9.2	8.1
Ranking	#2 in Fuzz Testing Software	#8 in Fuzz Testing Software
Best for	Free continuous fuzzing for open-source projects	Operating-system kernel fuzzing
Pricing model	Free	Free
Starting price	Free plan	Open source
Free plan	✓ (best)	Not checked yet
Free trial	—	—
Deployment	Cloud	Self-hosted
Platforms	Web	Linux, Windows, macOS
Support	Docs, Community	Community, Docs
Built for	Small business, Mid-market, Enterprise	Small business, Mid-market, Enterprise
Features OSS-Fuzz 3/3 · syzkaller 3/3
Coverage guidance	✓	✓
Crash triage	✓	✓
CI/CD support	✓	✓
Specs
Input generation methods	mutation	generation, mutation
Target types	source-code fuzz targets; untrusted user or network inputs; complex input formats	operating-system kernels and syscall interfaces: FreeBSD, Fuchsia, gVisor, Linux, NetBSD, OpenBSD, Windows
Execution mode	Cloud	Local
Supported languages	C/C++, Rust, Go, Python, Java/JVM, JavaScript, Lua	Not checked yet
Our review
Pros	Distributed fuzzing with libFuzzer, AFL++, Honggfuzz, and Centipede Sanitizer workflows, coverage reports, and fuzzer statistics Crash deduplication, reproduction, bug filing, and regression reporting	Generates and mutates syscall programs with coverage guidance Runs against virtual machines or physical devices Reproduces, minimizes, stores, and deduplicates kernel crashes
Cons	Limited to qualifying open-source projects Requires fuzz targets and build configurations for integration Cloud execution may not suit closed-source projects	Focused on operating-system kernels rather than general application fuzzing Requires teams able to build and instrument target kernels Local execution may demand kernel and device infrastructure
Our verdict	OSS-Fuzz is a Google service for qualifying open-source projects that need continuous testing against untrusted user or network inputs and complex input formats. Maintainers integrate fuzz targets and build configurations, after which the… Read the review →	syzkaller is an open-source, unsupervised coverage-guided fuzzer for operating-system kernels. It generates and mutates syscall programs, executes them through virtual machines or physical devices, collects kernel code coverage, and… Read the review →

Strengths and trade-offs

• OSS-Fuzz — where it wins

  • Distributed fuzzing with libFuzzer, AFL++, Honggfuzz, and Centipede
  • Sanitizer workflows, coverage reports, and fuzzer statistics
  • Crash deduplication, reproduction, bug filing, and regression reporting

  Where it doesn't

  • Limited to qualifying open-source projects
  • Requires fuzz targets and build configurations for integration
  • Cloud execution may not suit closed-source projects

• syzkaller — where it wins

  • Generates and mutates syscall programs with coverage guidance
  • Runs against virtual machines or physical devices
  • Reproduces, minimizes, stores, and deduplicates kernel crashes

  Where it doesn't

  • Focused on operating-system kernels rather than general application fuzzing
  • Requires teams able to build and instrument target kernels
  • Local execution may demand kernel and device infrastructure

• OSS-Fuzz9.2/10 · Free plan

  A cloud-based continuous fuzzing service for qualifying open-source projects.

  Visit OSS-FuzzFull verdict →
• Ssyzkaller8.1/10 · Open source

  A focused open-source choice for coverage-guided operating-system kernel fuzzing.

  Visit syzkallerFull verdict →