Customer: “Why is this app so big?”

Company: “Very cool features & lots of them + you have no way to check what I’m saying”

Not today corporate. Not today.

🧵 Why @ouraring is ~450 MB This might be a bit long, so TL;DR

Oura is just duplicating a bunch of images, json, & localizations. The size isn’t b/c it’s “powerful with many features”

Here’s what the size actually is 👇

Assets: 207.8 MB
Localizations: 49.2 MB
JSON: 35.5 MB
Audio: 26.5 MB

In 2024, @DraftKings decreased app size by 65% and improved app launch by +50%

Let’s take a look at what they did

🔬 Migrating from Xamarin → Native The main app binary went from 97 MB → 11 MB (the project also changed its name from DK.Gaming.iOS → Sportsbook)

Aside from that, much of the size decrease came from completely removing all dynamic-link libraries (.dll, used in Xamarin projects)

We got tagged to analyze this app on Thre*ds so we're posting it here too 🤭

🧵 Let's take a look at why the @intesasanpaolo iOS app is 699 MB 😳 A quick breakdown 👇

448 MB (64%) dynamic frameworks 🫠
72 MB (10%) main app target
74 MB (11%) of assets

We've got to stop meeting like this 😅

🧵 taking a look under the hood of the @Yelp iOS app Install size weighs in at ~318 MB, but ~4 MB of that is the watch app ⌚️

High-level breakdown:

130 MB dynamic frameworks
47 MB assets
34 MB main app target binary
26 MB localizations

For reference, @GoogleMaps weighs in at ~296 MB (7% smaller)

Did someone say app size?!

Here's why @thetrainline iOS app is so big 🧵 Total install size is 342 MB

Basic breakdown:

115 MB of Plugins
109 MB main app target binary
34 MB sqlite file 👀 (more on this later)
23 MB Dynamic Frameworks

The rest is assets, localizations, misc. Let's start with the Plugins 🔌

Do you want a paid wallpaper app from @MKBHD?

Maybe not? Well do you want to know how its made 🤓

🧵 Looking inside the new @Panels_art app, starting with ads 🎤 Ads have been a big topic

Panels is using Google Ads in both iOS (GAD) & Android

On Android, is the largest dependency in the dex com.google.android.gms.internal.ads

Oohhoho this one looks fun!

Let's take a look at why the @SantanderUK iOS app is at a whopping 613.3 MB and how 35% of it does nothing for the user 🧐 Right off the bat, it looks like most of the app (587.6 MB) is dynamic frameworks

Dylibs let you share code between targets, but are larger than static frameworks b/c static let's the compiler strip dead code. It's likely that Santander doesn't need ALL of those to be dynamically linked

Good question @VishalMalvi_ ! Here's what's going on behind the scenes of the @gmail iOS app 👇 Here are the biggest chunks of the app

Main app target - 225 MB
Plugins - 99 MB
Dylibs - 46 MB
Localizations - 130 MB 👀

Another day, another "How is this app so big tweet" 🤓

This time its the @DJIGlobal iOS app, which comes in at 1 GB A lot of the comments speculated that the app was large due to assets & while there are 155 MB of .mp4 video files, the bulk of the size is coming from ML models

Yes, we can be that someone 🤓

Looking into the @smartthings iOS app

https://x.com/austboston/status/1789247681849962517

Most the app is made up of dynamic frameworks - 633 MB of dylibs

The 4 largest dylibs take up ~350 MB

TVController2: 95.3 MB
SmartThingsCore: 91.1 MB
SmartThingsOnboarding: 90.8 MB
UnityFramework: 73.5 MB

... no clue what this app that "does nothing but tell me if I left the fridge door open" is using Unity for, but it's probably super important and needs to be there...

These are the best 🥲... breaking down why @LinkedIn iOS is half a GB

https://twitter.com/t3dotgg/status/1772328210900074786

Here's a top level view of the latest version of LinkedIn

300 MB for just dynamically linked frameworks & Plugins is...a lot. In fact, just the Dylibs & Plugins today are bigger than the entire app was back in November 2022 🫠

Finding accessibility issues in an app is an incredibly manual task that can take hours depending on the size. Which seems like a perfect place for ✨AI ✨

🧵Surfacing accessibility issues in the @Drizly app w/ AI 🧠 A quick background - our Snapshots product turns Previews into snapshots. A recent feature gives the ability to use AccessibilitySnapshot w/ one line

You don't need to write test code to get snapshot tests or to snapshot VoiceOver elements

Localization files translate text in your iOS app, you'll have at least one for every language you support

They're are also a common source of size bloat. The @FedEx iOS app has 130+ MB of localizations - over 50% of total size

🧵 Avoiding common pitfalls + a size saving script Localization bloat is usually from one of two causes

1. File duplication
2. Inefficient file formatting

Last week we wrote how @peacock reduced app size & app launch after moving from RN to native

By beautiful chance, another streaming app did the same this week. Did the same effects occur? Well, yes, no & it depends

🧵 Breaking down HBO's new Max app

https://twitter.com/Baconbrix/status/1661058851054010392

So, HBO Max is now Max. New app, new bundle id, new logo, & entirely new codebase. Let's start by comparing the iOS size and architecture

iOS
HBO Max (old app): v53.20.1 - 60.4 MB install size
Max (new app): v1.0.1 - 108.8 MB

The new iOS app is 48.4 MB (~80%) bigger

How did the @Twitter iOS app change over the last 6 months? Why did the latest release of Google Translate Android reduce app size by 1/3rd?

We try to make these questions easier to answer, which is why we're very excited about our newest feature, AI summaries of build diffs Jumping right in - Twitter v9.59.1 vs. v9.34.6 (iOS)

Overall size decreased by 34 MB, but how quickly can we identify what changed?

So, what does the @OpenAI ChatGPT iOS app look like under the hood? Well we took a look at a decrypted build

🧵 How the ChatGPT iOS app is made Overall install size is 41.9 MB and has a fairly simple structure. Here's our X-Ray treemap

What happens to an app's performance when it goes from react native -> native?

The @peacock app just made the switch on iOS & Android and had a significant change in size and startup time

🧵 Performance impact of switching to native A quick primer

RN let's you create mobile apps for Android and iOS using js & react. 1 codebase, 2 apps. It has an active community & there are certainly reasons you'd want to use RN

That said, if performance is important, native is going to be better

Notable iOS app size changes (install size) over the last week

📈 Increases
@BestBuy: +26.3 MB
@indeedjobs: +26.2 MB
@github: +10.6 MB

📉 Decreases
@Shopify: -24.5 MB
@Reddit: -24.0 MB
@googlechrome: -19.9 MB

🧵 How Best Buy could've avoided the increase altogether Best Buy v22.12.10 (previous)
Install Size: 148.6 MB

Best Buy v23.1.10 (latest)
Install Size: 174.9 MB

The difference in size between the two is due to the latest release being built with Xcode 14

The @CandyCrushSaga iOS app (v 1.243.0) is made up of over 22k files

Over 90% of the files are under 4 KB

🧵 Why having many small files = size bloat
+ how Candy Crush could cut it's install size by almost 20% The candy crush iOS app has an install size of 264.8 MB

55.5 MB of the app is "levels", which are made up of .txt files like `episode190Level3.txt` that define a level in JSON format

Inspired by this @Kelset tweet, let's take a look at how the @discord iOS app increased by 54.2 MB (36%) install size in version 158.0

https://twitter.com/Kelset/status/1612856519271354369

Discord Version 157.0 measured at 148.7 MB install size.

More than a third of the app was from main.jsbundle (RN)

The largest iOS apps all have a common problem

Localization files account for
23% (74 MB) of @Uber
23% (30 MB) of @WhatsApp
17% (53 MB) of @MicrosoftTeams
17% (50 MB) of Nike Run Club

🧵 Here's how Airbnb reduced the size of localizations by 82% with the help of Emerge First, a quick primer on localization files

Localization files are used to store translations of text in your app. Each file is a list of key-value pairs for text that need translating. These files exist for every language your app supports