Test the speed between your Macs.
A peer-to-peer speed-test app for diagnosing the network you actually have. No third-party servers. No telemetry.
$9.99 · One-time. No subscription.
What it measures
Four numbers, honestly measured.
Every test reports the same four headline numbers, using methodology that matches how real networks actually behave.
Median round-trip latency over 20 samples.
How steady that latency is, sample to sample.
Sustained throughput across 4 parallel TCP streams.
Same methodology, the other direction.
Why peer-to-peer
Measure the network you actually care about.
Most speed-test apps measure the path to a data center. That's fine for proving your ISP's plan, but it doesn't tell you anything about the wire between you and the thing you actually use.
Jitter Box measures the Wi-Fi between your bedroom and the router. The cable between your switch and your iMac. The VPN tunnel between your office and your laptop.
The link you care about — not the one your ISP wants you to look at.
How it works
Three steps. About ten seconds.
- 1
Install on two Macs.
Same app, no special role. Every install can act as either the tester or the target.
- 2
Flip on the receiver.
On one Mac, open Settings and toggle “Listen for incoming tests.” It listens on port 7878 by default.
- 3
Run the test.
On the other Mac, type the receiver's name or IP and hit Run Test. Ten seconds later you have your four numbers.
Privacy
Your data never leaves your network.
No analytics. No telemetry. No third-party SDKs. The app is sandboxed. Your test history lives in the macOS sandbox container on your Mac, and nowhere else.
Linux, too.
A free companion command-line tool runs the same receiver on anything Go cross-compiles to — a home NAS, a cloud VM, a Raspberry Pi. Same wire protocol, so a Mac test against a Linux box works exactly like a Mac-to-Mac test.
Download the free CLI$9.99. One-time.
No subscription.
Buy it once, own it forever. Updates land through the Mac App Store like every other Mac app you trust.
Requires macOS 14 Sonoma or later.