Masscan review
A free, open-source CLI for fast, large-range SYN scanning.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Masscan is a free, open-source command-line TCP port scanner for security teams, network administrators, and researchers who need to scan very large address ranges. Its core approach uses asynchronous SYN packets, with support for arbitrary IP-address and port ranges, IPv4 and IPv6, and internet-scale scanning. It runs on Windows, macOS, and Linux, making it suitable for environments where a cross-platform CLI is preferred.
The published feature set emphasizes control over scan execution. Users can configure the transmission rate, shard scans across machines or network adapters, and perform TCP banner checks for several protocols. Results can be saved as XML, binary, grepable, JSON, or list output, which supports different downstream workflows. The free pricing model and open-source license also make Masscan accessible for teams that want to run scans without a paid tier structure.
Masscan’s main trade-off is its narrow focus: it prioritizes speed and scale over intensive inspection of individual hosts. That makes it a strong choice for broad port discovery and exposure checks, but less suitable as a standalone tool when the primary need is deeper host analysis or a more guided interface. Teams comfortable with command-line operation and responsible for large IPv4 or IPv6 ranges should consider Masscan; teams seeking a broader detection workflow should choose a product designed around more extensive host inspection.
Masscan pros and cons
- Where it wins
- Asynchronous scanning supports very large address ranges
- Controls transmission rate and supports scan sharding
- Exports XML, binary, grepable, JSON, and list formats
- Where it doesn't
- Command-line deployment requires comfort with terminal workflows
- Focused on broad scanning rather than intensive host inspection
- No AI features
Masscan fact sheet, pricing and score →
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