Over-the-air and Mobile SDKs: Recommended Practices for Optimization

Optimize Your OTA Usage and Reduce Costs

Your data usage is influenced by three key factors: number of users, bundle size, and number of bundle releases. By following the optimization tips below, you can significantly reduce your bundle size and avoid overpaying.

1. Establish a Single Source of Truth

We highly recommend using a single source for all your translation data, ideally Lang Q. This means all modifications to keys and values should happen in your Translation Management System (TMS). Changes should then be pushed to other locations like your local development environment, GitHub, and servers.

Avoid modifying translations in multiple places simultaneously to prevent complex data management and inconsistencies, such as accidentally overwriting or deleting new keys. Remember that our mobile SDKs do not automatically export local changes back to Lang Q; you must use other tools for this.

2. Sync Local Files Before Building Apps

Before creating a new mobile app build, make sure it includes all translation data and that your local files are synced with Lang Q. Why? This practice is crucial for minimizing the OTA bundle size later, especially when combined with the other techniques in this guide.

The Golden Rule: OTA is only meant to deliver translations modified between app releases.

3. Limit OTA Bundles to Only Necessary Keys

When creating an OTA bundle on Lang Q, only include keys that were modified since the last app build. Do not include all translation data in every OTA bundle. App builds should contain all available translations, but OTA bundles should only contain the incremental changes.

How to Filter and Tag Modified Translations

To easily select only the relevant data, use Lang Q filters and tags:

Filter: Open your project editor and apply a new filter: Translation — was modified after — [Date of your last app release]. This isolates the keys that need an OTA update.
Tag: Select all filtered keys and use the bulk action to add a unique tag, such as post-release-1.
Build Bundle: Proceed to the Download page, choose your SDK format, and in the "Content to export" section, add the unique tag (post-release-1) to the Include tags field. Click Build only.

Your resulting bundle will contain only the modified data, significantly optimizing its size.

Performance Impact of Large Bundles

Bundle sizes larger than 2 MB can cause significant performance degradation, such as slow app startup or hanging, particularly for Android apps that use a dedicated database for translation storage. Optimize your bundles to keep them as small as possible.

4. Automate Bundle Generation Wisely

Automation is great, but we advise against overusing tools like the API or webhooks for OTA bundle generation.

Undesirable Approach: Creating a webhook that generates a new OTA bundle every time any translation is updated. Translators often make multiple changes before a final version, leading to dozens of redundant bundles and overused OTA capacity.

Recommended Approach: Create a webhook that listens to finalization events, such as project.task.closed or team.order.completed. This ensures a bundle is generated only when a set of translations is ready for deployment, preventing redundancy.

5. Utilize Bundle Freezes for Stability

A Bundle Freeze lets you assign a specific OTA bundle version to serve all users on a selected app build range.

Example: You can set app builds 1-5 to always use v1_2022_11_05, while later versions use v2_2022_12_30.

This prevents users on older app versions from accidentally receiving translations that were meant for newer builds.

Avoiding Translation Overrides with Bundle Freeze

A key use case is preventing a newer OTA bundle from overwriting local translations in a fresh app version.

Scenario:

App v1 released. OTA v1_2022_11_05 created.
A translation key (welcome) is updated on Lang Q.
App v2 is built with the new, updated welcome translation included locally.
App v2 is released. The Lang Q SDK automatically downloads the most recent OTA bundle, which is still v1_2022_11_05 or a subsequent, more recent one that overwrites the welcome key's local translation in v2.
Users on App v2 see the overridden (older) value.

Solution: Create a Bundle Freeze before building and releasing App v2. Freeze OTA bundle v1_2022_11_05 to only be served to App v1 users. This prevents the old OTA from being downloaded by v2, ensuring v2's correct local translation is used.

The Lite Bundle Trick

If a new app version (e.g., v3) contains all necessary translations locally and has no specific bundle freeze, it will still download the latest Production bundle by default. This redundant download can be fixed using a lite bundle trick:

Create an OTA bundle containing only a single key across all project languages (making it extremely small).
Create a new Bundle Freeze that distributes this lite bundle only to App v3.

This ensures a bundle is downloaded, but its minimal size minimizes performance impact while preventing the download of an unnecessarily large Production bundle.

6. Use OTA as an Enhancement, Not a Replacement

Lang Q mobile SDKs are designed to enhance your localization process, not completely replace native solutions. Continue to use in-built libraries and include local translation files in your app builds.

Only use OTA to deliver translation data that was modified between releases. It is not intended to be the sole mechanism for delivering all translations since the app's first release.