Subtitle a video with AI, on your PC
Word by word, nothing uploaded. Pick the style on a real frame and the video comes out ready for Reels, TikTok or YouTube.
Updated: October 2026 · 7 min read
To add subtitles to a video with AI on Windows: install AppGrabbit, open Download › Subtitles with AI, paste the link (YouTube, TikTok, Instagram, Facebook, X…) or drop your file, and click Get subtitles. The AI engine transcribes on your computer, word by word, and leaves an .srt, a .vtt and a .txt. Then you pick how they look on a real frame of your video (free) and Make the video burns them in. 1 credit · burning: Pro
Why the web's AI subtitle generators don't fit here
Almost everything you find when searching “automatic subtitles with AI” is a website: you upload the video (if it is on YouTube, you download it first), you wait, and the free plan leaves a watermark or caps your minutes. The video goes through someone else's servers. And there is one thing you notice on screen: many sync per sentence, so the text shows up before or after what is being said. Here the timing belongs to each word.
How AppGrabbit does it
From a link, the app downloads the full video (that is what gets subtitled); from a file of yours, it reads it where it is without moving it. It pulls the audio out with FFmpeg and transcribes it with Whisper (whisper.cpp) running on your PC, asking for the timing of every word: on your graphics card if you have an NVIDIA one, on the CPU if not. With those timings it builds the subtitles the way the trade does: two lines of up to 42 characters, breaks on silences and at the end of each sentence, never a lone word hanging. That is the .srt and the .vtt.
Then it shows you a real frame of your video with the subtitles on it, in three styles: Classic (two lines at the bottom, white with an outline), Box (on a black box, for busy backgrounds) and Center (three or four large words, with the spoken one lit up in yellow: the Reels and TikTok style). If you like it, Make the video burns the subtitles with the Poppins font that ships inside the app, so it looks the same on any PC. The MP4 comes out at the original size, named after your video plus “_subtitulos”, and lands in the Library.
How long it takes and how tight the sync is
- Transcribing — with an NVIDIA card, about 30 seconds per 10 minutes of video; CPU only, about 2 minutes per 10.
- Burning — a 51-second portrait video at 1080×1920 takes about 9 seconds.
- Sync, measured — on the final video, a subtitle appears on average 150 milliseconds before the voice, which is what subtitling guidelines recommend so the eye gets there in time; the burn adds not a single frame of delay.
- Wrong words — the Fast model about 8 in 100, the Accurate one about 5; mostly proper names. The .srt can be fixed in any text editor.
AppGrabbit against the other ways
| AppGrabbit | AI subtitle websites | CapCut and editors | YouTube Studio | |
|---|---|---|---|---|
| Your video never leaves your PC | ✓ Never | ✗ Goes to their servers | ✓ Yes | ✗ Uploaded to YouTube |
| Timing of every word | ✓ Yes | ~ Sometimes, paid | ~ Depends on the editor | ✗ Per sentence |
| Preview before paying | ✓ On your frame, free | ~ Watermarked | ✓ Yes | ✓ Yes |
| YouTube or TikTok link directly | ✓ Yes, downloads the video | ✗ You download and upload it | ✗ You download it | ✗ Only your videos |
| .srt and .vtt to take with you | ✓ Yes, with the credit | ~ Paid | ~ Depends | ✓ Only your own videos |
| Cost | 1 credit (5 free a month) · video: Pro $8.99/mo or $3.99 pass | Free minutes with watermark, then a subscription | Free with watermark, paid Pro | Free, your channel only |
What it is for, with examples
Reels, TikTok and Shorts: most are watched muted; the Center style with the lit word is the one that keeps people watching. Classes and tutorials: the .srt goes up to YouTube as closed captions and the video becomes accessible; that costs no Pro. Interviews and testimonials: Box over a moving background always reads. A video you shot on your phone: drop it in, it does not need to be on any network.
Step by step
- 1Install AppGrabbit for Windows — Download the free installer (everything included). Windows will say it protected your PC because the installer is not code-signed: click More info, then Run anyway.
- 2Open Download › Subtitles with AI — Paste the video link (YouTube, TikTok, Instagram, Facebook, X, Twitch…) or drop your mp4, mkv, mov or webm file. From the Library, any video has “Subtitles with AI” in its ⋯ menu.
- 3Click “Get subtitles” (1 credit) — The first time, the app gets the AI engine ready (a one-time download) and carries on by itself. The job shows at the top with its bar: Video · Transcription · Saving.
- 4Pick the style on a real frame — Classic (two lines at the bottom), Box (on a black box) or Center (three or four large words, the spoken one in yellow). “Previous / next moment” shows another sentence. This part is free.
- 5Click “Make the video” (Pro or the 7-day pass) — The subtitles are burned into the original video, at its own size. Follow it right there until “Video ready” and “Open folder”.
- 6Use the .srt anywhere — The .srt and .vtt have been in the Subtitles folder since step 3: upload them to YouTube as closed captions or load them in your editor, no Pro needed.
Frequently asked questions
Getting the subtitles (.srt, .vtt and .txt) costs 1 credit; Free comes with 5 a month. Previewing them on your video, in the three styles, is free. Burning them in (“Make the video”) is for Pro (USD 8.99 a month) or the 7-day pass (USD 3.99, no renewal).
The .srt and .vtt are plain text files: fix them in Notepad and use them on YouTube or in your editor. The video the app makes uses what the engine transcribed, with the timing of every word.
Yes, and it always transcribes on your PC: platform captions come per sentence, without the timing of each word, and the Center style needs to know when every word is spoken.
The engine detects the spoken language; you can pin it before starting if the video mixes languages. The subtitles come in the language of the audio, not translated.
The app tells you and gives the credit back. A music-only video gets no made-up text.
In the Subtitles folder inside your downloads folder, and in the Library. From the finished row in the queue, or from the .srt in the Library, “Choose style” takes you back to the preview step.
It is re-encoded in H.264 at the original size with AAC audio. On a phone or YouTube video you will not notice; the new file has your video's name plus “_subtitulos”.
Related guides
Subtitle your next video on your PC
Windows 10/11 · Get subtitles: 1 credit, 5 free a month · Make the video: Pro or 7-day pass