NetBox is a free and open source tool (Apache 2.0 license) used to model a network's entire presence through the use of purpose-built models, built to serve the needs of network engineers and operators.

Features include:

IP address management (IPAM) with full IPv4/IPv6 parity\
Automatic provisioning of next available prefix/IP
VRFs with import & export route targets
VLANs with variably-scoped groups
AS number (ASN) management
Rack elevations with SVG rendering
Device modeling using pre-defined types
Network, power, and console cabling with SVG traces
Power distribution modeling
Data circuit and provider tracking
Wireless LAN and point-to-point links
L2 VPN overlays
FHRP groups (VRRP, HSRP, etc.)
Application service bindings
Virtual machines & clusters
Flexible hierarchy for sites and locations
Tenant ownership assignment
Device & VM configuration contexts for advanced configuration rendering
Custom fields for data model extension
Support for custom validation rules
Custom reports & scripts executable directly within the UI
Extensive plugin framework for adding custom functionality
Single sign-on (SSO) authentication
Robust object-based permissions
Detailed, automatic change logging
NAPALM integration