Assetnote ASM vs Subra: 2026 Comparison
Assetnote ASM is a commercial external attack surface management tool by Assetnote. Subra is a free external attack surface management tool. Compare features, ratings, integrations, and community reviews side by side to find the best external attack surface management fit for your security stack.
CST VerdictBased on our analysis of NIST CSF 2.0 coverage, core features, company size fit, deployment model, here is our conclusion:
Mid-market and enterprise security teams managing sprawling external infrastructure will get the most from Assetnote ASM because its hourly asset discovery actually catches exposures before your business units spin up new services, not weeks after. The platform covers ID.AM and DE.CM across NIST CSF 2.0, meaning you're building a real asset inventory while monitoring it continuously, and the exploit-based verification eliminates the noise that buries actionable findings in traditional scanners. Skip this if your organization lacks the headcount to operationalize a workflow-driven program; Assetnote's strength is enabling lean teams to prioritize, not giving you a dashboard to ignore.
Security teams running manual subdomain discovery workflows or evaluating attack surface management on a budget should start with Subra; it wraps the open-source subfinder tool in a web interface that cuts the friction of command-line enumeration without requiring infrastructure spend. The 54 GitHub stars and free pricing model mean you can validate subdomain coverage gaps in minutes, not weeks of vendor evaluation. Skip this if you need continuous monitoring, prioritization scoring, or integration with your existing vulnerability management stack; Subra is a one-time discovery tool, not a platform.
