About NetTools

NetTools is a free platform of professional network engineering tools designed for network engineers, students, and IT professionals.

Tools available

• Subnet Calculator — IPv4 CIDR calculator with wildcard masks, broadcast address, and binary representation
• VLSM Planner — Variable Length Subnet Masking planner for optimized IP addressing
• Cisco IOS Script Generator — Generate interface configs, OSPF, ACLs, VLANs, and DHCP ready for the console
• Topology Simulator — Drag-and-drop network design with automatic IP assignment

Philosophy

All tools run entirely in your browser. No login required, no data collected, no registration. Just open the tool and use it.

Who built this

NetTools is built and maintained by a network engineer and software engineering student. The motivation is straightforward: the best tools for subnetting, Cisco IOS configuration, and network design are either locked behind expensive software licenses or buried in interfaces that were not designed for day-to-day professional use.

NetTools exists to provide professional-grade, free alternatives — tools that work the way engineers actually think about problems, without accounts, paywalls, or tracking. The primary audience is practising network engineers, students working toward CCNA and CCNP certifications, and IT professionals who need quick, accurate results.

Quality and maintenance

NetTools is open source and hosted on GitHub. The codebase is covered by 127 unit tests and a suite of end-to-end tests run on every push. All calculations are verified against RFC-correct results — the subnet calculator, VLSM planner, wildcard calculator, and CIDR summarizer are tested against known-correct outputs for a wide range of inputs. Tools are updated regularly as bugs are reported and new use cases are identified.

View the source code and test suite at github.com/AnderBarandiaran/nettools.

Contact

For bug reports, feature requests, or general questions, reach us through either of the following:

• GitHub — github.com/AnderBarandiaran/nettools (open an issue or discussion)
• Email — contact@nettools.engineer