10 UI Localization Best Practices for Developers

Want to make your app feel at home anywhere in the world? Here’s how to nail UI localization:

Plan early – bake localization into your development process
Use resource files for text – keep content separate from code
Make room for text expansion – some languages need more space
Get dates, times, and numbers right – format according to local norms
Support right-to-left languages – flip your layout when needed
Use Unicode for characters – ensure proper display across languages
Let users pick their language – make it easy to switch
Localize images and icons too – visuals matter across cultures
Test thoroughly – catch issues before users do
Keep it consistent across versions – use tools to manage translations

Quick Comparison:

Best Practice	Why It Matters	Key Tip
Plan early	Saves time and money	Separate content from code
Use resource files	Easier translation management	Name strings clearly
Text expansion	Prevents UI breaks	Design with 30-50% extra space
Proper formatting	Avoids confusion	Use built-in formatting tools
RTL support	Reaches more users	Mirror your layout
Unicode	Displays all characters correctly	Use UTF-8 encoding
Language selection	Improves user experience	Don’t force redirects
Image localization	Ensures cultural relevance	Avoid stereotypes
Thorough testing	Catches issues early	Use real devices and native speakers
Consistency	Maintains quality	Use translation management tools

Good localization isn’t just translation – it’s about making your app feel natural to users worldwide. Get it right, and you’ll boost engagement, reach new markets, and make your users happy.

What is UI localization?

UI localization is more than just translation. It’s about making your software feel like it was built for users in different countries and cultures.

UI localization basics

UI localization adapts:

Text (considering context and cultural nuances)
Date and time formats
Currency symbols
Number formats
Images and icons
Text direction (for languages like Arabic)

Here’s a real-world example:

Airbnb‘s Japan localization went beyond translation. They redesigned their booking flow to match local preferences, adding features like detailed cleaning schedules and specific check-in times. The result? A 73% boost in Japanese bookings within a year.

Localization vs. internationalization

These terms are often confused. Here’s the difference:

Aspect	Internationalization (i18n)	Localization (l10n)
Definition	Design for multiple languages/cultures	Adapt for specific languages/cultures
Timing	During initial development	After internationalization
Who does it	Developers	Translators and local experts
Focus	Flexible codebase	Tailored content and features

Internationalization sets the stage, localization brings it to life for specific markets.

Take Netflix:

Their internationalization let them expand quickly. But localization drove growth. In India, they created local content like “Sacred Games” and added Hindi support. Result? A 700% increase in Indian subscribers from 2017 to 2020.

Good localization is invisible. Users shouldn’t notice they’re using a localized version – it should just feel right.

1. Plan localization early

Planning for localization from the start can save you time and money. Here’s why it matters and how to do it right:

Build a localization-ready structure

Separate content from code: Use resource files for text. It’s easier to translate without touching the code.
Design with room to grow: Make UI layouts that can handle longer text. Some languages need up to 50% more space than English.
Use Unicode: Make sure your app can handle different character sets.
Make it adaptable: Design your software to work with various languages and regions without major changes.

Set up a smooth workflow

Bring in experts early: Get localizers on your team from the start. They’ll spot potential issues.
Create a localization kit: Give translators the tools they need – docs, style guides, and glossaries.
Test with fake text: Replace real text with placeholders to find problems before they happen.
Keep it rolling: Make localization part of your development cycle to handle updates easily.

Planning early helps you dodge common mistakes. Take Wix, for example. They found that only 35% of their 238 million users spoke English. This pushed them to focus on localization from the get-go.

Why plan early?
Cut costs and launch faster
Make users happier
Easier to maintain
Reach more markets

Localization isn’t just translation. It’s about making your whole product fit different cultures. Wix learned this when adapting for German users:

“Germans don’t like answering personal questions online. We changed questions to tasks and added reassuring text. This led to more German users getting a personalized experience.”

This shows how early planning and understanding culture can boost user engagement in new markets.

2. Use resource files for text

Keeping text separate from code is key for UI localization. Resource files are the way to go.

Organizing resource files

To make resource files easy to use:

Put them in a specific folder (like “App_GlobalResources”)
Make sure they’re compiled right
Use clear names for different languages

For example, in a .NET project:

resource.resx (default)
resource.de.resx (German)
resource.fr.resx (French)

This setup makes managing multiple languages a breeze.

Naming localized strings

Name your localized strings consistently. It helps avoid mistakes and makes sure you’re using the right resources. Here’s a quick comparison:

Text	Bad Name	Good Name
Save Changes	key1	common.modal.save_changes.header
Learn More	link-text	blog.cta.learn_more
Name	form.name1	form.name_person
First Name	rg_frm_fnam_lb	registration_form.label.first_name

Using clear, structured names gives context and helps both devs and translators.

When using resource files in your code, grab the localized strings the right way. Here’s an example in C#:

Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo("de-DE");
var LANGUAGE = resource.LANGUAGES;
Console.WriteLine(LANGUAGE);

This sets the culture to German and grabs the “LANGUAGES” value from the German resource file.

“The most likely reason for this is a typo in the Maximize resource name.”

This quote from Marin Bratanov of the Telerik team shows why getting your string references right is so important when working with resource files.

3. Plan for text expansion

Different languages take up different amounts of space. This can mess up your UI if you’re not careful.

Why does this matter? Simple:

Some languages are wordier (English to German, for example).
Longer text can break your UI (think cut-off words or hidden buttons).
Fixing it later? That’s gonna cost you.

Let’s look at some real numbers:

From English to	Content Type	How Much Longer?
German	Marketing	18%
German	Technical	16%
Spanish	Legal	15%
Spanish	Marketing	21%
Spanish	Technical	26%

See how it varies? That’s why you need to plan ahead.

Real-life oops: TED‘s mobile app hit a snag in German. Words got cut off. Not a good look.

Want to avoid that? Try these:

Keep it simple. Don’t get fancy with words.
Leave some breathing room in your design.
Don’t put text in images. Or if you do, make sure you can edit it.
Test it out. Fill your UI with random letters to see what breaks.
Set limits. Use tools that cap how long translations can be.

“Think about text expansion NOW. Don’t wait until later. It’ll save you headaches.”

That’s from a pro who knows their stuff. Take their advice.

4. Format dates, times, and numbers correctly

Dates, times, and numbers can make or break your UI. Here’s how to handle them right:

Dates and Times

Countries show dates and times differently:

Country	Date Format	Time Format
USA	MM/DD/YYYY	12-hour
Germany	DD.MM.YYYY	24-hour
Japan	YYYY/MM/DD	24-hour

Use Intl.DateTimeFormat in JavaScript to avoid confusion:

const date = new Date("2024-01-27T14:00:00Z");
console.log(date.toLocaleDateString("en-US")); // 1/27/2024
console.log(date.toLocaleDateString("de-DE")); // 27.1.2024
console.log(date.toLocaleDateString("ja-JP")); // 2024/1/27

Numbers

Number formats vary too:

Country	Number Format
USA	1,234.56
Germany	1.234,56
India	1,23,456.78

Use Intl.NumberFormat to handle this:

const number = 1234567.89;
console.log(new Intl.NumberFormat('en-US').format(number)); // 1,234,567.89
console.log(new Intl.NumberFormat('de-DE').format(number)); // 1.234.567,89
console.log(new Intl.NumberFormat('hi-IN').format(number)); // 12,34,567.89

Quick Tips

Detect user’s locale
Use built-in formatting tools
Test with various locales
Consider cultural differences
Allow user preferences

“Proper date, time, and number formatting is not just about aesthetics—it’s about clear communication across cultures”, says Akshay Kothari, CPO at Notion.

Getting these details right shows respect for your users and makes your app feel natural to them.

5. Support right-to-left languages

Over 820 million people use RTL languages like Arabic, Hebrew, and Persian. Here’s how to make your UI work for them:

Mirror your layout

Flip everything:

Logo and nav? Top right.
Text? Right-aligned.
Sidebars? Left to right.

Adjust text and fonts

RTL text needs tweaks:

Bump up font size by 3 points.
Skip italics and all caps.
Make sure RTL scripts render correctly.

Handle directional elements

Some things need special care:

Element	What to do
Arrows, icons	Flip horizontally
Progress bars	Reverse direction
Breadcrumbs	Mirror order
Calendars	Mirror layout

Keep some elements LTR

Not everything flips:

Numbers (dates, phone numbers)
Latin text in RTL content
Media player controls

Test thoroughly

Zoomcar‘s Egypt expansion in March 2022 shows why testing matters. Their UX lead said:

We had to question every component, image, and gesture to ensure they worked for RTL users. It was a major undertaking, but essential for our success in the Egyptian market.

To test:

Use Android’s “Force RTL layout direction”
In iOS, use Xcode’s Pseudo RTL language
Get native speakers to review

6. Use Unicode for characters

Unicode is a must for displaying characters correctly across languages. Here’s why it matters for UI localization:

What is Unicode?

Unicode is a standard that gives each character a unique number. It works across platforms and programs, solving language support issues in apps.

Benefits of Unicode

Global reach: Supports 144,000+ characters from almost every language, including emoji.
Space-saving: UTF-8 encoding uses less space for common characters.
Consistent display: Text looks right on different systems and devices.

Using Unicode in your UI

To make Unicode work for you:

Use Unicode strings for text in your app.
For databases, pick NVARCHAR(n) over VARCHAR.
Use UTF-8 encoding for web pages (95% of the web does).
Handle Unicode code points (like U+00639) correctly.

“UTF-8 saves space. Common characters like ‘C’ take 8 bits, while rare ones like ‘💩’ take 32 bits.” – Adam Hooper, software developer

Tips for success

Keep encoding consistent across platforms.
Choose UTF-8 when you can.
Test your UI on different systems to check character display.

Remember: Unicode is key to making your UI work for users worldwide. It’s not just about supporting languages – it’s about creating a seamless experience for everyone.

7. Add language selection options

Language selection is crucial for UI localization. It lets users pick their preferred language, making your app or website more user-friendly.

Here’s how to nail it:

Make it easy to find

Put your language selector in obvious spots:

Header or footer
Use a globe icon (not flags)
Label it in the current language

Airbnb nails this. They use a globe icon in the top menu and footer on desktop, and in the footer on mobile. Simple and effective.

Use native language names

List languages in their native format:

English
Español
Deutsch
日本語

This helps users quickly spot their language.

Don’t force redirects

Let users choose their language. Don’t automatically redirect based on location. It’s annoying.

ASOS does this well. They suggest a language but let users easily change it.

Separate language and location

Some folks might want to browse in English while shopping from France. So:

Let users pick their language
Let them choose their location separately
Allow currency selection if needed

Revolve.com gets this right. They let users pick shipping country, site language, and currency independently.

Think about mobile

For mobile designs, consider space:

Use a compact dropdown
Or a separate language selection page

Tesla groups languages by region in a dropdown. It saves space but stays user-friendly.

8. Localize images and icons

Images and icons are key in UI design, but they’re not one-size-fits-all. What works in one culture might flop in another. Here’s how to nail it:

Pick smart visuals

Steer clear of stereotypes or symbols that could rub users the wrong way. A thumbs-up might be great in the US, but it’s a no-go in some Middle Eastern countries.

Mind your colors

Colors speak different languages across cultures. Red screams danger in the West but spells luck in China. Kendra Schaefer, a Chinese UI expert, found that Chinese users prefer brighter app colors than Westerners.

Go for universal symbols

The ISO has cooked up symbols that work across cultures. They’re perfect for getting your point across without words.

Don’t forget image text

Got text in your screenshots or infographics? That needs translating too.

Flip for right-to-left

For languages like Arabic or Hebrew, mirror your images and icons to match the text flow.

Icon smarts

Icons aren’t just eye candy. They’re navigation tools. But they need to make sense locally. Here’s a quick cheat sheet:

Do	Don’t
Use abstract designs	Use hand gestures
Show nature or objects	Use religious symbols
Use standardized warning symbols	Use flags for languages

Learn from oops moments

Sony’s PlayStation controllers had different default controls in Japan versus the rest of the world. Why? In Japan, “O” means yes and “X” means no. It’s flipped elsewhere. This tiny oversight left users scratching their heads.

Tool up

Image editors like Photoshop or GIMP can help you tweak visuals. For bigger projects, try localization platforms like Transifex or Crowdin. They make juggling multiple languages a breeze.

Get local feedback

Always run your designs by people in your target market. They’ll catch things you might miss.

9. Test localized versions thoroughly

Testing localized versions can make or break your UI localization. It’s not just about typos – it’s about making sure your app works perfectly for users around the world.

Here’s how to ace your localization testing:

Test early and often

Don’t wait until the end. Test throughout development. You’ll catch issues early and save time and money.

Use real devices

Forget emulators. Test on actual devices to mimic real-world use. BrowserStack offers 3000+ real devices and browsers for thorough testing.

Look beyond text

Check more than just translations:

UI layout and design
Localized input functionality
Date, time, and number formats
Currency symbols and conversions
Right-to-left language support

Create a checklist

A detailed checklist keeps you on track. Include:

Text visibility and overlap
Button sizing
Layout logic
Grammar and terminology consistency
Cultural appropriateness of images and colors

Work with native speakers

Native speakers catch things automated tools miss. They spot awkward phrasing or culturally insensitive content.

Watch for text expansion

Some languages need more space. Make sure your UI handles text up to 70% longer than the original.

Language	Potential Text Expansion
German	Up to 35%
French	Up to 20%
Spanish	Up to 30%

Avoid common mistakes

Keep an eye out for:

Broken strings
Untranslated text
Wrong character encoding
Misaligned text in buttons or menus

Track issues

Use a good system to log and follow up on localization bugs. It prevents repeat issues and speeds up fixes.

10. Keep localized versions consistent

Consistency across localized versions is crucial. Here’s how to nail it:

Use translation management tools

Tools like Crowdin are your secret weapon. They let you manage translations in one place, making it easy to track progress and update content.

“Crowdin gives you real-time updates on translation status. You can spot issues fast and keep quality high.” – Crowdin Team

Implement translation memory

Translation memory (TM) is a game-changer. It stores past translations for reuse, saving time and money while keeping your voice consistent.

Here’s what TM can do for you:

Benefit	How it helps
Save time	Reuse translations for similar content
Cut costs	Fewer words to translate = lower costs
Stay consistent	Key terms always translate the same way
Boost quality	Standardized content improves overall translation

Create a style guide

A solid style guide keeps everyone on the same page. Include:

Go-to terms
Brand voice rules
Formatting dos and don’ts
Cultural tips

Stick to one terminology

Don’t mix “email”, “e-mail”, and “Email.” Pick one and use it everywhere.

Match UI and docs

If your UI button says “Send”, your docs should too. Don’t confuse users with mixed terms.

Centralize localization

Get all teams using the same tools and processes. It keeps things consistent across your products.

Conclusion

UI localization isn’t optional. It’s crucial for global success. Here are the key takeaways:

Plan early
Use the right tools
Localize ALL elements
Test rigorously

Get it right, and you’ll see results. Copperleaf Technologies boosted revenue after localizing for new markets.

“Localization isn’t just translation—it’s about forging bonds with customers by delivering an intuitive, tailored experience”, says Akshay Kothari, CPO at Notion.

Remember: Good localization creates a seamless, culturally relevant experience. It’s your ticket to winning over users worldwide.