Bean Network Tester

Break your network on purpose. See how your app really behaves.

Every app looks great on a fast, stable office connection. Then a real user opens it on hotel Wi-Fi, a crowded train, or a phone dropping from 5G to one bar - and things fall apart. Bean Network Tester lets you recreate those exact conditions on your own Windows machine, on demand, so you can find the bugs before your users do.

It sits underneath your whole system and shapes real traffic: add latency and jitter, drop and corrupt packets, throttle bandwidth, duplicate or reset connections, blackhole oversized packets, and more. Point it at everything, or at a single app, IP or port. No proxy setup. No code changes. It works with any program on the machine, over any TCP/IP protocol, and even over localhost.

Why this tool is useful

Testing on a perfect connection tells you almost nothing about the real world. Loading spinners that never appear in the office lock up on a slow link. Timeouts that never fire suddenly fire. Recconnection logic that was never exercised turns out to be broken. Bean Network Tester turns "it works on my machine" into "it works on a bad train Wi-Fi in December", which is the connection your users actually have.

It is built for the people who have to answer for that:

• QA and test engineers who need to reproduce a flaky, connection-dependent bug and prove it is fixed.
• Game developers and game QA who need to feel high ping, jitter, packet loss and sudden disconnects the way players do.
• Network engineers, sysadmins and support staff who need to recreate a customer's bad connection to understand a complaint.

How it works

Bean Network Tester captures live packets as they pass through the Windows network stack, applies the impairments you have chosen, and sends them on their way - all in real time, while your app keeps running. Start it and stop it whenever you like; your application never has to restart.

You decide exactly what gets touched. Filter by direction (inbound, outbound or both), by protocol (TCP, UDP, ICMP), by destination IP or port, or by process - including a process and its child processes, so targeting a browser catches its network worker too. A compact expression language handles lists, ranges, wildcards, regular expressions, CIDR blocks and both IPv4 and IPv6.

When you have a setup you like, save it as a profile, pick a named preset, or build a timeline scenario that changes conditions over time - "start clean, drop to 3G after twenty seconds, blackout in a tunnel, recover". Six real-world scenarios ship with the tool, from congested office Wi-Fi to a mobile handoff. Set a seed and every random impairment becomes repeatable, so a bug you found once you can find again - and hand to a developer with an exact reproduction.

There is also a full command-line mode with proper exit codes and machine-readable output, so the same tool that runs on your desk can run inside an automated test pipeline.

Key features

• Latency, jitter, packet loss, corruption, duplication, reordering-style delays
• Bandwidth throttling (separate up and down limits)
• Link flapping, TCP reset, SYN drop, MTU black-hole, NAT timeout, latency spikes
• Target by direction, protocol, IP, port, or process (and its children)
• Powerful filter expressions: lists, ranges, wildcards, regex, CIDR, IPv4 + IPv6
• Presets, saveable link profiles, and editable timeline scenarios
• Seeded, reproducible runs with a one-click reproduction report
• Full CLI with exit codes and JSON output for CI/CD
• Live statistics, a connection view, and a timestamped event log
• Bilingual interface (English / Polish), dark theme, sharp on any display
• No telemetry. It captures traffic on your machine, and that data never leaves it. No accounts, no tracking, no phone-home.
• Free for personal and commercial use.

Requirements

Windows 10 or 11 (64-bit). Administrator rights are needed to load the capture driver (the tool asks when it needs them). The first launch may show a SmartScreen notice because the build is not yet certificate-signed. The app probably works on older x64 Windows, not tested there.

Documentation: https://donislawdev.com/bean-network-tester-documentation/

Bean Network Tester is built with an AI-assisted workflow.