Shodan vs SurfaceDiff: What's the Difference?
People searching "Shodan alternative" are usually looking for one of two different things: another way to search what's already known about a target on the public internet, or a way to be told when something changes on infrastructure they're actually responsible for. Shodan is genuinely excellent at the first. It was never designed for the second. Here's the actual difference, honestly.
What Shodan is
Shodan is a search engine that continuously scans the public internet and indexes what it finds - open ports, banners, service versions, certificates - across essentially every reachable IP address, whether or not the owner asked for it or even knows it's being scanned. Point it at an IP or run a query and you get back whatever it already has on file. That's enormously useful for security research, threat intelligence, and quick one-off lookups: "what does the internet currently know about this address?"
What Shodan isn't built for
It isn't watching your specific domains on your schedule. Its scan cadence for any given target is its own, not yours. It doesn't verify who owns what it indexes - it indexes everything, which is exactly why it's a research tool and not something you'd want doing your organization's change monitoring: there's no workflow for "we reviewed this and it's expected," no audit trail of who acknowledged what and why, and no concept of an account scoped to just your domains.
What SurfaceDiff is
SurfaceDiff only ever scans domains an account has explicitly added and verified ownership of - never anything else, even if it happens to share a server with something you do monitor. Each of your domains gets scanned on a schedule you control, every scan is diffed against the last one, and only real changes become incidents: a new port, a changed certificate, a service that disappeared. Findings can be reviewed and muted with a reason, and every action is kept as a permanent, attributed record - see what an EASM tool actually does for the fuller picture.
When to use which
- Reach for Shodan/Censyswhen you want a one-off lookup on any target - including checking what's already publicly known about your own IPs - or you're doing broader research that isn't about one specific set of domains you own.
- Reach for SurfaceDiffwhen you want ongoing monitoring of domains you're actually responsible for, with alerts, a review workflow, and a record you can point to later.
They're not really substitutes for each other - most teams that need both end up using an internet-wide index for research and a continuous monitor for their own domains, not one instead of the other.
Run a free scan on a domain you manage to see the difference directly, or check pricing for ongoing monitoring.