FlowViewer

At a glance

• Editor score
  6.5 / 10
• Pricing
  Free plan
• Best for
  Basic free flow reports and long-term graphs
• Free plan
  Yes
• Paid from
  Free
• Facts checked
  20 Sep 2026

• Where it wins

  • Free, open-source flow reports with extensive filtering
  • IPv4 and IPv6 analysis across several flow protocols
  • Long-term graphs, saved reports, and operational dashboards

• Where it doesn't

  • Requires exported flow data and an existing collection setup
  • Designed for on-premises Unix servers or virtual appliances
  • Does not provide verified application or conversation analysis

Our verdict on FlowViewer

FlowViewer is an open-source network traffic analysis toolset for organizations that export NetFlow or related flow data from network devices. Its browser-based suite includes FlowViewer for text-based reports and filtering, FlowGrapher for traffic graphs, and FlowMonitor for long-term traffic monitoring. It is intended for network operations and security teams that manage their own flow collection infrastructure, rather than teams looking for a hosted monitoring service.

The suite covers NetFlow v5, NetFlow v9, IPFIX, and sFlow through its underlying components. Reports can be filtered by addresses, ports, interfaces, AS numbers, protocols, TCP flags, and next-hop values, with support for both IPv4 and IPv6 analysis. Graphs show bits per second, flows per second, and packets per second. Long-term views include peak, minimum, mean, and 95th-percentile values, while saved reports, saved filters, and dashboards support recurring operational monitoring. The documentation describes sFlow support through SiLK as available.

FlowViewer is free and open source, with no paid software tier described in its published pricing model. The vendor also offers paid installation, router configuration, training, and custom support services. Deployment is on premises, using a Unix server or virtual appliance, so the product fits teams prepared to operate their own flow environment. Choose it for basic flow reports, detailed filters, and long-term traffic graphs without a software license cost. Choose an alternative when verified application-level or conversation analysis is a central requirement, or when a hosted deployment is preferred.

Your product? Our editors can test FlowViewer in depth and publish a review, labelled as paid · from $149/mo →

FlowViewer pricing

FlowViewer fact sheet

Alternatives to FlowViewer

• ManageEngine NetFlow AnalyzerA broad traffic-analysis suite with a free edition and paid tiers for growing networks.9.3
• ntopngA broad self-hosted traffic analysis suite with a capable free Community plan.9.2
• SNSolarWinds NetFlow Traffic AnalyzerA focused choice for multi-vendor flow analysis, drill-downs, and historical reporting.9.0

See all FlowViewer alternatives →

Featured on iTechGuides

FlowViewer is listed in our Network Traffic Analysis Software directory. Add the badge to your site — it links back to this page.

<a href="https://www.itechguides.com/products/flowviewer/"><img src="https://www.itechguides.com/best/badge/flowviewer.svg" alt="Featured on iTechGuides" width="230" height="46"></a>

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.

Last updated 7 Oct 2026 · How we research and update