Free tool
Add captions to a Twitter video on X
To add captions to Twitter video posts, now on X, make an SRT from the clip with the free generator below. Then post from X on the web: add the video, select Upload caption file (.srt) below it, choose the file with Upload captions and select Done.
- Free
- SRT for X
- No sign-up
Drop your video or audio file here, or Choose your video or audio file
MP4, MOV, MKV or WebM video, or MP3, M4A or WAV audio. Up to 30 minutes of each file, 3 free files a day. The language is detected automatically.
Clipping podcasts and talks for X? NoteOwl transcribes the full recordings on your Mac, unlimited, and saves SRT captions with each speaker’s name.
How it works
How do you caption a clip before posting it on X?
Drop the clip on the generator first. It sends the sound off in short pieces to be transcribed, then lays the words out as numbered captions in step with the speech. Skim them, download the SRT and keep it in the folder with the clip.
- 1
Use the final clip
The trimmed version you’ll post, as MP4, MOV or WebM, so the captions start on time.
- 2
Scan the captions
The first 30 minutes of the file are captioned, each caption showing its timing.
- 3
Download SRT
One file, named after your clip, ready for X’s caption upload.
How do you upload an SRT file to a post on X?
On X in a web browser, upload the video to your post, then select Upload caption file (.srt) below it. In the pop-up, select the Upload captions button, choose the SRT from your computer and select Done. The caption language appears under the video; then post.
- 1
Add the video
Upload it to a new post on X on the web.
- 2
Upload caption file (.srt)
Select it below the video.
- 3
Upload captions
In the pop-up, select the button and choose the .srt from your computer.
- 4
Done, then post
Select Done, check the language name under the video, and post.
Can you add a caption file in the X app on your phone?
No. X’s help says uploading a caption file is currently available on the web only. Make the SRT, then post the video from x.com in a browser on your computer, where Upload caption file (.srt) sits right below the video.
What SRT format rules does X list?
X’s Media Studio help asks for captions in chronological order, times written HH:MM:SS,mmm with a comma before the milliseconds, and one space before and one space after the arrow between the two times. The SRT made here follows all three.
Editing the file by hand? Keep the comma and the spaces around the arrow. An SRT that runs early or late can be moved as a whole with the subtitle shifter.
- Order
- What X asks forCaptions in chronological order
- In the file made hereNumbered from 1 in the order spoken
- Time format
- What X asks forHH:MM:SS,mmm
- In the file made here00:00:02,140
- Arrow
- What X asks forOne space before it and one after
- In the file made here00:00:02,140 --> 00:00:05,300
| Rule | What X asks for | In the file made here |
|---|---|---|
| Order | Captions in chronological order | Numbered from 1 in the order spoken |
| Time format | HH:MM:SS,mmm | 00:00:02,140 |
| Arrow | One space before it and one after | 00:00:02,140 --> 00:00:05,300 |
What is the Subtitles tab in X Media Studio?
A second way in, for verified subscribers who use Media Studio: select the video there, open the Subtitles tab, pick the language of your SRT and select Upload. X supports one subtitle file per video there, so choose the language most of your viewers need.
The generator writes the captions in the language spoken in the clip. For a version in another language, translate the SRT with the subtitle translator before uploading it.
Can you get captions with speaker names for X clips?
With NoteOwl you can. On your Mac it transcribes recordings you import using on-device AI models, keeps track of each voice and saves SRT subtitles that open with the speaker’s name, unlimited. A two-person podcast clip then makes clear who is talking without extra on-screen text.
FAQ
Questions about captions on X
Where is the caption option when posting a video on X?
Below the video in the post you’re writing, on the web: select Upload caption file (.srt). It isn’t in the mobile app, because X currently offers caption uploads on the web only.
Do viewers see the captions automatically?
X’s help says that when the video plays and a viewer has captions enabled, they appear toward the bottom of the video. On the web, the CC control is where viewers switch them.
Does X accept VTT caption files?
X’s caption upload is labelled for .srt files, so upload the SRT, which is the generator’s first download.
Can I add captions in more than one language on X?
X’s Media Studio help says it supports one subtitle file per video. Pick the language that matters most; the generator writes the language spoken in the clip and doesn’t translate it.
What’s the longest clip I can caption?
Each file is captioned for up to 30 minutes, and you can do 3 files a day without an account. Anything past that point in a longer file is left uncaptioned.
Do you upload my video to make the SRT?
No. The page reads the video on your device and sends its soundtrack in short pieces to a cloud AI transcription service, which discards each piece once it’s transcribed. The SRT is assembled in your browser, and NoteOwl holds on to nothing.
Keep exploring
More subtitle generator tools
- Subtitle generatorA free AI subtitle generator: drop in a video or recording and download SRT or VTT subtitles timed to the speech, two short lines per cue; only the sound is sent, nothing is stored
- Subtitles for Zoom recordingsMake subtitles for a Zoom recording and add them where the recording is shared
- Subtitles for Google DriveMake an SRT and add it to a video in Google Drive with Manage caption tracks, on a computer
- Subtitles for PowerPointMake a WebVTT caption file and insert it into a video on a slide: Playback > Insert Captions on Windows and Mac, Edit Captions on the web
- Subtitles for VLCMake an SRT for any video and load it in VLC with Add Subtitle File, or name it like the video so VLC finds it
Related
- Subtitles for LinkedInMake an SRT and attach it as the caption file when you post a video on LinkedIn from a computer
- Subtitles for FacebookMake an SRT already named the way Facebook requires (video.en_US.srt) and upload it to a video or Reel
- Subtitle generatorTurn a recording into an SRT subtitle file with timecodes and speaker names, on your Mac
Speaker-named captions for every clip, on your Mac
Free to download. Runs entirely on your Mac.
macOS 26 or later · Apple Silicon (M1 or newer) · 16 GB memory minimum, 24 GB recommended
About NoteOwl
NoteOwl is private AI meeting notes and memory for the Mac. It captures meetings without a bot joining the call, labels every speaker, writes summaries and action items, and builds a memory of every conversation that you can chat with — fully offline, because the speech recognition and the AI run on the Mac itself. Dictation into any app is free; Pro is a one-time purchase.
NoteOwl pricing: what’s free and what Pro adds
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