CaptionStack

Subtitle your videos in every language you speak — and do the whole job on your iPhone. Import a clip, pick your languages, and CaptionStack transcribes what you said, then translates it into the rest. Your spoken language sits on top, emphasised; each other language stacks beneath it in its own colour. Edit everything, then export a video with the subtitles burned in at full quality. Subtitle your videos in every language you speak — and do the whole job on your iPhone. Import a clip, pick your languages, and CaptionStack transcribes what you said, then translates it into the rest. Your spoken language sits on top, emphasised; each other language stacks beneath it in its own colour. Edit everything, then export a video with the subtitles burned in at full quality. EVERYTHING STAYS ON YOUR DEVICE Transcription uses Apple's on-device speech recognition. Translation uses Apple Intelligence's on-device language model. Your video never leaves your iPhone — no servers, no accounts, nothing to sign up for. Once the language models are installed, it all works in airplane mode. SPEAK 10 LANGUAGES, SUBTITLE 15 Transcribe in German, English, Spanish, French, Italian, Portuguese, Japanese, Korean, Chinese and Cantonese. Translate into all of those except Cantonese, plus Dutch, Danish, Norwegian, Swedish, Turkish and Vietnamese. Portuguese comes in Brazilian and European, Spanish in Spain and Latin American, Chinese in Simplified and Traditional. BUILT FOR THE WHOLE JOB • Transcribe the language you actually spoke • Auto-translate into every other language you picked • Edit any caption's text, per language • Nudge start and end times to the frame you want • Raise or lower individual captions to dodge whatever's behind them • Add captions anywhere on the timeline, delete the ones you don't want • Restyle live: colour per language, text size, outline weight, line spacing, distance from the bottom WHAT YOU SEE IS WHAT YOU PUBLISH The live preview and the exported video are laid out by the same code, so the finished file is exactly what you designed. Full quality. No watermark. Ever. PROJECTS THAT WAIT FOR YOU Every project is saved on your iPhone. Close the app mid-edit and pick it up later, exactly where you left off. Rename or delete projects whenever you like — nothing is kept anywhere else. ONE PURCHASE Buy it once. No subscription, no in-app purchases, no ads, no account. REQUIREMENTS iOS 26 or later. Automatic translation requires an Apple Intelligence capable iPhone (iPhone 15 Pro or later) with Apple Intelligence turned on in Settings. Transcription, editing, styling and export all work on any iPhone running iOS 26 — without Apple Intelligence you simply type the other languages yourself. The first time you use a given language, iOS downloads Apple's model for it. That is a one-time system download handled by iOS, not a connection to any server we run. After it completes, everything runs offline.