How the Tinder iOS App reduced the size of our localizations by 95% using Emerge

Tinder ships their iOS app to 190+ countries in 50+ languages. That localization overhead was costing them 51MB of install size.

The Tinder iOS team tackled a sneaky performance problem: Apple's 4KB minimum file size for code signing meant hundreds of tiny localization files were bloating their app. They combined Bazel build optimizations with Emerge's SmallStrings compression tool to dramatically reduce their footprint.

Key Takeaways

• Reduced download size by 10.7MB and install size by 51.3MB
• Collapsed 50+ localization files per target into single compressed files
• Used Bazel aspects to traverse build graph and merge strings automatically
• Applied LZFSE compression to keys and values separately
• Zero impact to developers: changes hidden behind code generation

The team discovered even more optimization opportunities during this work, including a way to dynamically remove unused strings at build time.