# GRASSMARLIN vs Nautilus OT: side-by-side comparison (2026)

[GRASSMARLIN](https://cybersectools.com/tools/grassmarlin) is a free [OT asset discovery](https://cybersectools.com/categories/asset-discovery) solution. [Nautilus OT](https://cybersectools.com/tools/nautilus-ot) is a commercial [OT asset discovery](https://cybersectools.com/categories/asset-discovery) solution by [Nautilus](https://cybersectools.com/companies/nautilus). Features, integrations, deployment and the company behind each one, side by side.

## Side-by-side comparison

| | GRASSMARLIN | Nautilus OT |
|---|---|---|
| Pricing model | Free | Commercial |
| Category | OT Asset Discovery | OT Asset Discovery |
| Verified | No | No |
| Deployment type | On-Premises | On-Premises |
| Company size fit | Mid-Market, Enterprise | Mid-Market, Enterprise |
| GitHub stars | 1,000 | – |
| Last commit | Aug 2017 | – |
| Company | – | Nautilus |
| Headquarters | – | – |

### Use cases and capabilities

| | GRASSMARLIN | Nautilus OT |
|---|---|---|
| SCADA | Yes | – |
| Network Topology | Yes | – |
| Critical Infrastructure | – | Yes |
| Network Visibility | – | Yes |
| Network Monitoring | – | Yes |
| Anomaly Detection | – | Yes |
| Ransomware | – | Yes |
| Vulnerability | – | Yes |
| Security Compliance Training | – | Yes |
| Network Discovery | – | Yes |

### Core features

**GRASSMARLIN**

No features listed.

**Nautilus OT**

6 features listed. Sign in on the page to see them.

## Which one fits you

Based on what each listing shows: deployment, company size, price and open source.

- [GRASSMARLIN](https://cybersectools.com/tools/grassmarlin) fits if you need a free product and you want an open-source product.

## GRASSMARLIN vs Nautilus OT FAQ

Common questions when comparing GRASSMARLIN vs Nautilus OT for OT asset discovery.

### What is the difference between GRASSMARLIN and Nautilus OT?

**GRASSMARLIN**: Passively maps and visually displays ICS/SCADA network topology for network security.

**Nautilus OT**: Built by Nautilus.

The table above shows where their features, integrations, deployment and company size fit differ.

### Who makes GRASSMARLIN and Nautilus OT?

**GRASSMARLIN** is open-source with 1,000 GitHub stars. **Nautilus OT** is made by Nautilus. The vendor behind a product decides its roadmap, support, and longevity, so check each company's profile before you commit.

### Is GRASSMARLIN a good alternative to Nautilus OT?

Often, yes. GRASSMARLIN and Nautilus OT are both OT Asset Discovery products. Key differences: GRASSMARLIN is Free while Nautilus OT is Commercial, GRASSMARLIN is open-source. Use the table above to see where features, deployment and company size fit differ.

## Related comparisons

- [GRASSMARLIN vs Vantelis Data Acquisition Platform](https://cybersectools.com/compare/grassmarlin-vs-vantelis-data-acquisition-platform)
- [GRASSMARLIN vs SAM Intelligence](https://cybersectools.com/compare/grassmarlin-vs-sam-intelligence)
- [GRASSMARLIN vs Redinent Deep Asset Intelligence](https://cybersectools.com/compare/grassmarlin-vs-redinent-deep-asset-intelligence)
- [Nautilus OT vs Vantelis Data Acquisition Platform](https://cybersectools.com/compare/nautilus-ot-vs-vantelis-data-acquisition-platform)
- [Nautilus OT vs SAM Intelligence](https://cybersectools.com/compare/nautilus-ot-vs-sam-intelligence)
- [Nautilus OT vs Redinent Deep Asset Intelligence](https://cybersectools.com/compare/nautilus-ot-vs-redinent-deep-asset-intelligence)

## Alternatives to each

- [See all GRASSMARLIN alternatives](https://cybersectools.com/alternatives/grassmarlin)
- [See all Nautilus OT alternatives](https://cybersectools.com/alternatives/nautilus-ot)

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Source: https://cybersectools.com/compare/grassmarlin-vs-nautilus-ot

For AI agents: each product above has its own Markdown page (add .md to its URL, for example https://cybersectools.com/tools/grassmarlin.md). Every CybersecTools shortlist is listed at https://cybersectools.com/shortlists.md.

More on GRASSMARLIN and Nautilus OT: funding, momentum, hiring and news, plus the full product and company record, are available through the Mandos MCP Server (paid plans), which connects to AI assistants: https://mandos.io/mcp?utm_source=cybersectools.com&utm_medium=compare-md