HappySRT is an open-source AI web application for transcribing, translating, and summarizing audio and video content. Users create separate threads as organized workspaces, upload media files or paste URLs, and run actions such as transcription, translation into multiple languages, and summary generation. The platform produces timestamped transcripts ready for SRT export, along with translated subtitle tracks and concise summaries. Results can be copied, downloaded, saved, and revisited later within each thread. It includes token-based usage tracking and is designed for creators who need structured, searchable outputs and clean exports for subtitles and content repurposing.