Hei.io

Hei.io turns audio and video into captioned, dubbed versions across 140+ languages using auto transcription, 440+ AI voices and voice cloning. Upload a file or YouTube link, review the transcript, pick a voice and export MP4, MP3 or SRT.

Hei.io is a browser-based dubbing studio built around a single workflow: take an existing audio or video file, transcribe it, translate it, and hand back a version that speaks a new language. The platform advertises support for more than 140 languages and a voice library of 440+ synthetic voices, with popular language pages (Chinese, Spanish, Hindi, Portuguese, French, German, Japanese) offering sample clips so you can judge output quality before committing. In practice the tool works in three stages. You upload a file from your computer or paste a YouTube link, then set the source and target languages; subtitle files in SRT or VTT can be supplied and custom dictionaries applied to steer transcription. Hei.io generates captions with timing already aligned, so manual syncing is not part of the job. From the transcript you start dubbing with a stock AI voice or with Voice Cloning, which aims to preserve the original speaker's timbre across languages. The finished asset downloads as MP4, MP3 or SRT, and projects can be reopened for edits and redubs. That puts it closest to dedicated localization suites rather than general video editors. Teams that already cut footage elsewhere use Hei.io purely as a caption and voiceover layer, while solo creators use it to publish one recording across several markets without booking voice talent. The homepage highlights a claimed 90 percent translation accuracy for voiceover and captions, and cites usage by media, telecom and public sector organizations as social proof. Voice Cloning is the most constrained feature: it is listed for up to 32 languages rather than the full 140+, so anyone planning cloned dubs in a niche language should confirm coverage first. Lip Sync is flagged as coming soon, meaning mouth movement is not matched to the new audio yet. Pricing tiers and usage limits are not published on the homepage, so cost comparison against rivals has to start with the free trial.