Best syzkaller Alternatives in 2026
The top syzkaller alternatives are Mayhem, OSS-Fuzz and ClusterFuzz: 15 fuzz testing software our editors would look at instead of syzkaller, in our ranking order.
syzkaller: A focused open-source choice for coverage-guided operating-system kernel fuzzing. Where it falls short: focused on operating-system kernels rather than general application fuzzing.
Switching from syzkaller? For most fuzz testing software buyers the best syzkaller alternative is Mayhem, built for teams needing broad managed fuzz testing. OSS-Fuzz has a free plan.
Why People Look for a syzkaller Alternative
- 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
Quick Picks by What You Need
- Best overallMayhem9.4
Teams needing broad managed fuzz testing
Visit Mayhem - Best free optionOSS-Fuzz9.2
Has a free plan
Visit OSS-Fuzz
All 15 syzkaller Alternatives, Ranked
Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.
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Best forTeams needing broad managed fuzz testing
- Better than syzkaller:
- Editor score 9.4 vs 8.1
Mayhem brings broad hybrid fuzz testing, triage, and regression coverage to CI workflows.
- Coverage guidance
- CI/CD support
- Crash triage
9.4/10★★★★★Visit Mayhem -
Best forFree continuous fuzzing for open-source projects
- Better than syzkaller:
- Editor score 9.2 vs 8.1
A cloud-based continuous fuzzing service for qualifying open-source projects.
- Coverage guidance
- CI/CD support
- Crash triage
9.2/10★★★★★Visit OSS-Fuzz -
Best forOrganizations needing managed fuzzing infrastructure
- Better than syzkaller:
- Editor score 8.9 vs 8.1
A broad, self-managed fuzzing platform for continuous security and stability testing.
- Coverage guidance
- CI/CD support
- Crash triage
8.9/10★★★★☆Visit ClusterFuzz -
Best forGeneral-purpose native and binary fuzzing
- Better than syzkaller:
- Editor score 8.7 vs 8.1
A broad, free fuzzer for native code, binaries, libraries, and file-processing tools.
- Coverage guidance
- CI/CD support
- Crash triage
8.7/10★★★★☆Visit AFL++ -
Best forAPI teams testing REST, GraphQL, and RPC
- Better than syzkaller:
- Editor score 8.5 vs 8.1
A broad, free API testing tool for teams covering REST, GraphQL, and RPC.
8.5/10★★★★☆Visit EvoMaster -
Best forSecurity teams wanting AI-assisted broad workflows
- Better than syzkaller:
- Editor score 8.3 vs 8.1
An AI-assisted fuzzing platform spanning local, cloud, API, firmware, and embedded workflows.
- Crash triage
8.3/10★★★★☆Visit FuzzForge -
Best forJVM application and library fuzzing
- Better than syzkaller:
- Editor score 8.2 vs 8.1
A free, open-source JVM fuzzer with strong CI and build-tool integration.
- Coverage guidance
- CI/CD support
- Crash triage
8.2/10★★★★☆Visit Jazzer -
Best forCommercial firmware security testing
A commercial platform for deep, hardware-independent firmware security analysis.
- Coverage guidance
- CI/CD support
- Crash triage
8.0/10★★★★☆Visit Metalware -
Best forBlack-box protocol and binary testing
A broad black-box fuzzer for protocol, binary, file, hardware, DLL, and API testing.
- Crash triage
7.9/10★★★★☆Visit Fortra -
Best forBroad local native and binary fuzzing
A broad local fuzzer for native code, binaries, APIs, and network servers.
- Coverage guidance
- Crash triage
7.8/10★★★★☆Visit Honggfuzz -
Best forJavaScript engine fuzzing
A focused open-source fuzzer for finding crashes and coverage in JavaScript engines.
- Coverage guidance
- CI/CD support
- Crash triage
7.7/10★★★★☆Visit Fuzzilli -
Best forSelf-hosted OpenAPI and GraphQL testing
A free, self-hosted API fuzzer for schema-driven Python testing.
7.6/10★★★★☆Visit Schemathesis -
Best forStateful REST API fuzzing from OpenAPI
A focused choice for dependency-aware REST API fuzzing and reproducible findings.
7.5/10★★★★☆Visit RESTler -
Best forSpecialized embedded-firmware fuzzing
A focused choice for rehosting and fuzzing embedded firmware without physical hardware.
- Coverage guidance
- CI/CD support
7.4/10★★★★☆Visit Fuzzware -
Best forProtocol reverse engineering and fuzzing
A free, open-source toolkit for modeling, simulating, and fuzzing proprietary protocols.
7.3/10★★★★☆Visit Netzob
syzkaller Alternatives: Common Questions
What is the best alternative to syzkaller?
Mayhem: #1 in our Fuzz Testing Software ranking, with an editor score of 9.4 out of 10. Mayhem brings broad hybrid fuzz testing, triage, and regression coverage to CI workflows.
Is there a free alternative to syzkaller?
Yes. OSS-Fuzz, ClusterFuzz, AFL++, EvoMaster and FuzzForge have a free plan or a free tier (11 of the 15 alternatives on this page).
Why do people look for syzkaller alternatives?
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.
How do I switch from syzkaller?
Export your data from syzkaller (most tools have an export in their settings). Sign up for the alternative; start on its free plan or trial if it has one. Import your export and set up the integrations your team relies on. Run both side by side for a short while, then cancel syzkaller.
How to Switch from syzkaller
- Export your data from syzkaller (most tools have an export in their settings).
- Sign up for the alternative; start on its free plan or trial if it has one.
- Import your export and set up the integrations your team relies on.
- Run both side by side for a short while, then cancel syzkaller.
syzkaller vs Each Alternative
| # | Tool | Free plan | Paid from | Input generation methods | Target types | Coverage guidance | Crash triage | Score |
|---|---|---|---|---|---|---|---|---|
| 8 | syzkaller | Free | generation, mutation | operating-system kernels and syscall interfaces: FreeBSD, Fuchsia, gVisor, Linux, NetBSD, OpenBSD, Windows | Yes | Yes | 8.1 | |
| 1 | Mayhem | hybrid | Linux binaries; Windows PE binaries; TCP/UDP applications; REST APIs; gRPC APIs; containers; automotive vECUs | Yes | Yes | 9.4 | ||
| 2 | OSS-Fuzz | Yes | Free | mutation | source-code fuzz targets; untrusted user or network inputs; complex input formats | Yes | Yes | 9.2 |
| 3 | ClusterFuzz | Free | mutation, generation, hybrid | binary formats, HTML, JavaScript, browser DOM, native programs | Yes | Yes | 8.9 | |
| 4 | AFL++ | Yes | Free | mutation | source-code targets, binary-only targets, file inputs, stdin inputs, Android native libraries, Win32 PE binaries | Yes | Yes | 8.7 |
| 5 | EvoMaster | Yes | Free | 8.5 | ||||
| 6 | FuzzForge | Yes | generation | codebases, binaries, containers, APIs, GraphQL, protocols, firmware, embedded systems | Yes | 8.3 | ||
| 7 | Jazzer | Yes | Free | mutation, generation | JVM applications, Java, Kotlin, Scala, Clojure, JNI/native libraries | Yes | Yes | 8.2 |
| 8 | Metalware | generation and mutation, with symbolic input generation | ELF and raw .bin firmware; ARM Cortex-M, embedded peripherals, DMA, RTOS, and bare metal targets | Yes | Yes | 8.0 | ||
| 9 | beSTORM | generation | network protocols, file formats, hardware, DLLs, APIs, binary applications | Yes | 7.9 | |||
| 10 | Honggfuzz | Free | mutation | file inputs, standard input, APIs, binaries, network servers | Yes | Yes | 7.8 | |
| 11 | Fuzzilli | Free | mutation, generation, hybrid | JavaScript programs and JavaScript engines/interpreters | Yes | Yes | 7.7 | |
| 12 | Schemathesis | Yes | Free | 7.6 | ||||
| 13 | RESTler | Yes | Free | 7.5 | ||||
| 14 | Fuzzware | mutation | ARM Cortex-M firmware; Infineon AURIX TriCore firmware; MMIO and interrupt-driven embedded systems | Yes | 7.4 | |||
| 15 | Netzob | Yes | Free | mutation, generation | network protocols, structured files, text protocols, delimiter-based protocols, fixed-field protocols, variable-length/TLV protocols, IPC, drivers and devices | 7.3 |
Head-to-Head
- syzkaller vs Mayhem
- syzkaller vs OSS-Fuzz
- syzkaller vs ClusterFuzz
- syzkaller vs AFL++
- syzkaller vs EvoMaster
- syzkaller vs FuzzForge
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Last updated · How we research and update