# Simulate a slow network for iOS and Mac apps | Lagsmith

> Simulate slow networks for one app: 3G, Edge, high latency, jitter and packet loss. Test loading states, retries and timeouts in iOS Simulator and Mac apps.

Source: https://lagsmith.com/simulate-slow-network

# Simulate a slow network and test your app on bad connections

Loading states, retries, timeouts and offline handling only get tested if you simulate a slow network. Lagsmith does it for one app at a time, with presets in real numbers and conditions that change over time.

[Download for Mac](https://lagsmith.com/download)

## What to test on a slow network

-   **Loading states**: does a spinner or skeleton appear, or a blank screen?
-   **Timeouts**: what happens when a request takes 30 seconds?
-   **Retries**: does the app retry, and does it give up sensibly?
-   **Double submits**: can the user tap Pay twice while the first request is slow?
-   **Images and large downloads** on Edge and 3G.
-   **Going offline** mid-request. [Airplane Mode for one app](https://lagsmith.com/simulate-airplane-mode-ios-simulator).

## Slow networks, in numbers

Lagsmith includes Edge, 3G, DSL, LTE, WiFi, Very Bad Network and 100% Loss, by the same names as Apple’s Network Link Conditioner. For example, 3G is 780 kbps down with 200 ms latency. Or set your own:

-   download and upload bandwidth,
-   latency and jitter,
-   packet loss,
-   which hosts it applies to.

Profiles change conditions over time, so you can test a connection that gets worse and recovers.

## Without slowing down your Mac

Only the app you pick is slowed down. [How this compares with Network Link Conditioner](https://lagsmith.com/network-link-conditioner-alternative).

## Frequently asked questions

### How do I simulate 3G on a Mac?

Pick the app in Lagsmith and choose the 3G preset (780 kbps down, 200 ms latency). Only that app slows down.

### Can I add jitter and packet loss?

Yes. Custom conditions include download and upload bandwidth, latency, jitter and packet loss.

### Can conditions change during a test?

Yes. Profiles change conditions over time instead of holding one fixed speed.

### Can I run slow-network tests in CI?

Yes. Use the XCTest UI test helper, the ivar command line tool or the local HTTP API. [Automation docs](https://lagsmith.com/docs/automation).

## Slow down one app, not your whole Mac

Free to download, with a 14-day Pro trial. No account, no card. Requires macOS 13 Ventura or later.

[Download for Mac](https://lagsmith.com/download) [Compare with Network Link Conditioner](https://lagsmith.com/network-link-conditioner-alternative)