SubtitleMate for YouTube

A lightweight extension that remembers your caption language and playback speed, then applies them on every YouTube video.

Year: 2026
My role: Product definition · UX · Development · Launch
Platform: Chrome Extension

View on Chrome Web Store

The problem

Every video starts with the same ritual: open the settings menu, hunt for the subtitle track, pick a language and adjust the playback speed. On multi-language videos the right track hides behind extra menus, and none of it sticks between videos.

Product approach

SubtitleMate turns the ritual into a one-time setup. The popup remembers your caption mode, source and target language and preferred speed; a background script applies them to every video automatically, with API-first control and a UI fallback for resilience.

Key product decisions

API first, UI as fallback

The extension drives YouTube's player API through a main-world bridge, and only falls back to simulated menu clicks when the API path is unavailable.

Check before retrying

The script verifies the current caption and speed state first, skips when already correct, and caps retries at three so a stubborn video never loops.

Minimal permissions

No activeTab or scripting permissions — the extension runs only on YouTube watch pages and stores all settings locally.

From need to launch

Prototype

Started with simulated clicks, then rebuilt on the player API after the first approach proved fragile.

Harden

Added pre-checks, deduplication and retry caps to survive YouTube UI changes and multi-language videos.

Ship

Aligned store screenshots with the real UI, moved the privacy policy into the repo and shipped v1.0.2.

What I learned

The feature was easy; the environment was not. Building layered fallbacks for a page that keeps changing taught me more about defensive engineering than any greenfield project.

Store promo graphics

Screenshots from the Chrome Web Store listing.