Open Network Diagram

Overview

Rather than treating an infrastructure map as a static drawing, Open Network Diagram stores its data in JSON. That makes the record reusable, back-upable and optionally versionable, while the visual interface helps document how machines, virtual machines, devices and racks relate. The project is licensed under GNU GPL v3.

The scope is focused: it covers topology, inventory, cabling and basic IP address management, not a general-purpose infrastructure-management platform. It is a sensible fit for a home lab or similarly bounded environment; teams needing built-in access controls should look elsewhere or put an authenticated proxy in front of it.

Key features

The network view maps topology with Ethernet labels, subnets and VLANs. Hosts & VMs provides inventory and service mapping, including expandable VM lists per machine. Rack view records managed racks, U positions and equipment height, supports side-by-side shelf items and lets users click through to the editor. Together, these views provide more operational context than a network-only diagram.

The IPAM panel reports subnet utilisation, detects duplicate IP addresses and suggests the next free address. Cable connections can record type, colour and length; colour-coded links and hover details make those attributes easier to follow in the map. This is useful for keeping a small environment legible, but the described capabilities are focused on documenting infrastructure rather than managing it broadly.

In self-hosted mode, changes autosave to JSON, writes are persisted atomically and the last five rolling backups are retained. Docker-first deployment supports writable data volumes and Docker Compose. Published images support AMD64 and 64-bit ARM, including Raspberry Pi systems. The runtime exposes GET and PUT operations at /api/network-data, which gives API-capable stacks a direct way to read or update the data.

There is no runtime dependency on external APIs, and the locally vendored icon catalogue supports offline-friendly operation. That reduces reliance on external services, though it does not remove the need to protect the data itself: topology records may reveal host names, addresses, MAC addresses and other sensitive infrastructure details.

Pricing

Open Network Diagram has one free plan: 0.00 USD per free. It includes self-hosted Docker deployment under GNU GPL v3, with device inventory, IP address management, network diagrams and relationship mapping. There are no paid tiers or seat limits described. The cost advantage is clear for users able to host and secure it themselves; hosting and access protection remain their responsibility.

Platforms

Open Network Diagram is available as a web application, a self-hosted deployment and an API. Docker images cover AMD64 and 64-bit ARM, so the same self-managed approach can run on standard AMD64 hosts or Raspberry Pi systems.

Who it's for

Choose it if you run a home lab and want one maintained record of network topology, machines, virtual machines, device relationships, cabling and rack placement. The JSON source of truth, backups and local operation suit builders who value control over their infrastructure data and are comfortable with Docker.

It is a poor fit for a deployment reachable by others unless access is restricted. Open Network Diagram provides neither authentication nor TLS. Its read-only mode, enabled with NETWORK_READ_ONLY=true, can prevent changes in a public demonstration, but it does not hide configured topology or authenticate viewers. The project advises against directly exposing a writable deployment to the internet; use a firewall, LAN or VPN, or an authenticated reverse proxy that terminates TLS.

Pros and cons

Pros

• Structured, reusable source of truth: JSON can be backed up, reused and optionally versioned, rather than leaving infrastructure details trapped in a diagram.
• Several complementary infrastructure views: network, Hosts & VMs and rack views cover topology, inventory and physical placement.
• Practical IPAM and cabling detail: subnet utilisation, duplicate detection, next-IP suggestions and cable attributes help keep a small map actionable.
• Self-hosted and offline-friendly: Docker Compose, writable volumes, local icons and no runtime external API dependency support local operation.

Cons

• No built-in authentication or TLS: a reachable instance needs protection through network restrictions or an authenticated TLS-terminating proxy.
• Read-only is not a privacy control: public demonstrations can still expose configured topology, which may include sensitive infrastructure identifiers.
• Self-hosting carries operational responsibility: users must provide deployment, backups beyond the retained five files if needed, and access controls.

Alternatives

For a broader shortlist, see Network Documentation Software.

• Scanopy is worth considering when you need a freemium option with a free self-hosted Community Edition capped at one network and one user seat, or want its paid Starter plan at 11.99 USD per month billed yearly.
• GestióIP is a better fit when IPAM is the central need: its free standard package is complemented by a Configuration Management Module priced at 400.00 USD per year for up to 50 devices.
• LOGINventory may suit teams prioritising device inventory, with a free Forever-Free tier capped at 20 devices and an Inventory360 plan priced at 6.50 EUR per year.
• Nautobot is an option for teams seeking a self-managed community platform intended for exploration, initial workflows and limited production deployments.
• Obelinf is an alternative for a small, bounded setup: its free Personal plan allows one user, one organization, one site, four racks and 30 devices.
• Danbyte is another free, open-source, self-hosted option, with all features included and no seat license, enterprise tier or license expiry.
• ITFlow is a free, open-source self-hosted option if its broader IT documentation approach better matches your needs; hosting and sponsor support are paid services.
• phpIPAM is a straightforward alternative when free, self-hosted IP address management is the priority.

Verdict

Open Network Diagram is a strong choice for home-lab builders who want a free, self-hosted map that combines network topology, inventory, rack placement and practical IPAM in a reusable JSON record. Choose it for that focused breadth and local control; choose another tool, or secure it behind an authenticated TLS proxy, if you need access protection built in.