Network Diagram Builder

What is a network diagram?

A network diagram is a picture of how devices are connected. It shows what equipment exists, such as a router, switch or firewall, and what sits between each one. Diagrams are used to plan a new network, explain an existing one to a colleague, record a change, and troubleshoot a fault by spotting the device that should be on a path but is not.

Why draw a network diagram?

How to use this network diagram builder

1. 1Start from a template if one fits, or choose Blank canvas and build it yourself.
2. 2Drag a device from the library onto the canvas. You can also search for it and press Enter to add it at the centre.
3. 3Connect devices by dragging from a handle on the right of one device to the handle on another. The connection type and line style can be changed afterwards.
4. 4Select a device or a connection to edit its label, address and notes in the Properties panel.
5. 5Use Undo and Redo freely. Every add, delete, move and property change is a step you can step back through.
6. 6Save the diagram to this browser when you are happy with it, then export JSON, SVG or PNG for documentation.

Starting templates

Six layouts cover the usual shapes of network, from a home connection to a tiered enterprise design. Load one as a starting point and edit it freely.

Common network diagram symbols

There is no single worldwide standard for these shapes, but the conventions below are common enough that a reader will usually guess correctly.

Router

A rounded box with crossed arrows. Moves traffic between different networks and holds the default gateway for your devices.

Switch

A box with crossed arrows, often on a horizontal line. Connects devices on the same layer 2 network and carries VLANs as virtual LANs.

Firewall

A brick wall or a box with a shield. Sits at the boundary between networks and enforces rules about what may pass.

Wireless access point

A box with radiating waves. Bridges wireless clients to the wired network, often with a dotted line for the wireless link.

Server

A stacked box. A plain rectangle in this tool is a server, which keeps a large diagram readable at small sizes.

Cloud or external service

An outline or a cloud shape. Marks anything outside your control, such as a provider's data centre or a SaaS application.

Physical and logical diagrams

A physical diagram shows where equipment actually sits: which rack, which floor, which cable run. A logical diagram shows how traffic flows regardless of location, so two offices on different continents can appear side by side. The same network needs both, because a physical drawing cannot show a VLAN and a logical drawing cannot show a cable length.

How to make a diagram readable

• Give every device a name. A box labelled Router 01 tells a reader far more than an empty box.
• Flow from left to right, with the internet or uplink on the left and end users on the right.
• Label connections only where the type matters, such as a trunk, a VLAN number or a VPN tunnel. A diagram covered in labels stops being readable.
• Group related devices into a segment or data centre note when a diagram outgrows one screen.
• Keep one diagram per scope. A diagram showing the whole estate at once usually shows too little of anything.

What this tool does not do

• It does not read your network. There is no scanning, no discovery and no ping, so nothing is detected automatically.
• It does not import Visio, draw.io or Lucidchart files. Import accepts the JSON this tool exports.
• It does not validate your addressing plan. It points out malformed addresses and duplicate IPs, but it cannot tell you whether a subnet design is right.
• It does not sync or share. Saving is local to this browser, so a diagram on another device or another browser is a separate copy.

Frequently asked questions