Size a web application firewall properly

Describe the applications once, and the tool sizes them across F5, Imperva and Citrix NetScaler using each vendor's own sizing method - layer-7 requests per second, application throughput, new TLS handshakes per second and the connection table, never the headline figure on a datasheet. It picks the smallest platform that still has headroom, shows every step of the arithmetic, maps the licences each vendor actually needs, draws the connectivity and inspection design, and exports the lot as Word, PowerPoint and Excel.

48 models 35 licence SKUs 3 vendors 5 insertion modes

1. The design

What this is, so the exported documents carry the right names.

Design name Customer Site or environment Prepared by Compliance driver Sites in scope

2. The traffic

A measured figure always wins. Give whatever you have: the tool takes the highest number the form can produce, because a WAF has to survive the worst of them.

Application profile Peak requests per second measured, at the busy hour Peak application throughput (Mbps) Concurrent users Average transaction size (KB) Concurrent connections Protected applications Encrypted traffic (%) Certificate key type Requests per TLS connection keep-alive reuse

Re-encrypt to the back-end servers doubles the TLS work - a second handshake per connection

3. Where it sits, and how it is inserted

The insertion mode changes the processing cost and, for out-of-band, whether the WAF can block at all.

Where the WAF sits Insertion mode High availability Cluster nodes only used for a cluster Form factor

Growth per year (%) Over years Design headroom (%)

5. Vendors to compare

All three by default. The result page shows one vendor at a time with a tab for each.

F5 BIG-IP Advanced WAF (formerly ASM) Imperva Imperva WAF Gateway / Cloud WAF Citrix NetScaler NetScaler Web App Firewall (AppFirewall) - Premium edition

Nothing is saved unless you ask for it. Guests see results; saving and exporting need a free account.

Performance figures in the catalogue are indicative values held for relative sizing between models, last reviewed 2026-09. Every vendor publishes against a different test profile and revises the numbers per release, so confirm the final model against the current datasheet before quoting.

WAF Sizer by NiyyasoftHelp