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

[Tinder](https://yomu.fyi/company/tinder) · Tinder · Feb 26, 2025

**Type:** Problem & solution

## Summary

Supporting over 50 languages across numerous statically linked targets led to a substantial build size footprint in Tinder's iOS application. Because Apple's code signing mandates a minimum 4KB per file, shipping dozens of localized files per target inflated the final application package. Tinder addressed this by stripping comments and whitespace, merging localized strings into a single file per language via custom Bazel rules and Aspects, and compressing the strings using Emerge's SmallStrings tool into LZFSE files. The runtime decompresses these files dynamically through existing code-generated string accessors. Consequently, Tinder reduced download size by 10.7MB and install size by 51.3MB with no impact on developer workflows.

## Context

Tinder supports over 50 languages across more than 190 countries, resulting in at least 50 localization files per build target for static linking. Apple's code signing imposes a minimum overhead of 4KB per file regardless of content size, significantly inflating the final IPA size.

## Approach / What changed

Tinder stripped translator comments and whitespace, then used custom Bazel rules and Aspects to merge localization files into a single file per language. They integrated Emerge's SmallStrings to compress keys and language values into LZFSE files decompressed dynamically at runtime via existing code generation.

## Takeaways

- Apple code signing requires at least 4KB per file, making high file counts a major contributor to application binary bloat.
- Collapsing per-target localization files into a single file per language reduced Tinder's download size by 5.5MB and install size by 30.1MB.
- Compressing strings with Emerge SmallStrings into LZFSE files saved an additional 5.2MB in download size and 21.2MB in install size.

**Tags:** [iOS](https://yomu.fyi/topic/ios), [Performance](https://yomu.fyi/topic/performance)

[Read original post](https://medium.com/tinder/how-the-tinder-ios-app-reduced-the-size-of-our-localizations-by-95-using-emerge-af624d5b0ff0)