Local AI transcription
OpenAI Whisper runs in your browser via WebAssembly — no upload, no API key, no third-party cloud.
"Hello, world!"
"Amazing video!"
"Subscribe now!"
"Watch this..."
No upload · No signup · Pure SRT out
Convert MP4 to SRT in your browser
Drop your MP4 file and Captionly transcribes the audio with AI Whisper, then exports a clean SRT subtitle file. No upload, no quota, no watermark. Works with MP4, MOV, WebM, MKV and more.
Sometimes you just need an SRT file — to drop into Premiere, CapCut, DaVinci Resolve, an FFmpeg pipeline, or YouTube Studio. Captionly is a free MP4 to SRT converter that does the transcription locally with AI, so you don't ship your video to anyone's servers and you don't wait in a render queue. Drop the file, edit any wrong words, download the .srt. That's it.
Free AI subtitle generator — drop a video to get started
Drop your video here
or click to browse your files
Supports MP4, MOV, AVI, WebM (max 500MB)
100% freeno signupno watermark50+ languagesSRT · VTT · TXTprivate by defaultAI-powerededit on the flyTikTok-readypodcast-readycreator-loved100% freeno signupno watermark50+ languagesSRT · VTT · TXTprivate by defaultAI-powerededit on the flyTikTok-readypodcast-readycreator-loved
✦ A no-nonsense MP4 → SRT pipeline
A no-nonsense MP4 → SRT pipeline
Built for editors who want the subtitle file, not a hosted "experience".
Industry-standard SRT
Plain SubRip text with HH:MM:SS,ms cues. Drops cleanly into Premiere, FCP, DaVinci, CapCut, Resolve, FFmpeg, YouTube Studio and Vimeo.
Auto language detection
Captionly detects the spoken language automatically and transcribes in 50+ languages including English, Spanish, Portuguese, French, German, Japanese and more.
Click-to-fix transcript
Spot a wrong word, click it, type the right one. Timings stay locked and the SRT export reflects every edit.
Glossary for recurring fixes
Map "Whisper-misheard" phrases to the correct spelling once — Captionly applies them across the whole transcript and every export.
Also exports VTT and ASS
Need WebVTT for HTML5 video or ASS for full styling? One click switches the format. Same transcript, three exports.
✦ ShowcaseReal videos.
Real videos.
Real captions.
See how creators of every kind are using Captionly. Drag to browse, click to play.
EN0:42
Neon Pop
thischangedmylife
EN1:18
Box Highlight
andthat'swhenIquit
EN0:21
Gradient Wave
onemorerep!
EN2:04
Karaoke
Tokyoatgoldenhour
EN0:56
Bounce
bestadviceever
ES0:33
Outline
novasacreer
EN0:28
Shadow Pop
let'sgo!victory
EN1:45
Underline
watchthistrick
EN0:52
Glitch
thisisinsane
EN0:38
Minimal
feelthebeat
EN0:19
Rainbow
hitthatmove
EN0:47
Pill
waitforit
✦ FAQ
MP4 to SRT — quick technical answers
Practical Qs for editors who'd rather have the file than a UI.
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Free · Local · No watermark
Get the SRT file
Drop your MP4, edit if needed, download a clean SRT. No upload, no signup, free forever.