Auto Subtitle Generator

Detects speech, generates timed captions in white text with a black outline, and burns them into your video. Free for videos under 60 seconds, three a day.

100% free
No signup needed
Browser-based

Loading subtitle tool…

Why use Jupitrr's free subtitle generator?

Short, timed lines

Captions come back timed per word and grouped into lines of up to four words, so each line appears as it is spoken.

Burn-in on your device

After detection, the export runs in your browser. The finished file is never uploaded.

MP4 and SRT

Download the captioned video, the SRT file, or both.

How it works

Drop a short video

MP4, MOV, WebM, or M4V under 60 seconds and 500 MB.

Generate and edit

Hit Generate Subtitles. Fix any word in the cue list, then set the font size and position from the bottom.

Burn in and download

Hit Burn In Captions to export the MP4 in your browser, or download the SRT.

What is an auto subtitle generator?

Speech to timed captions, then captions onto the picture.

An auto subtitle generator listens to the speech in a video, turns it into text with timestamps, and places that text on screen in sync. With Jupitrr's Auto Subtitle Generator, detection runs on a transcription service and the burn-in runs on your device, and you get a captioned MP4 plus an SRT. It is a small slice of the captioning inside the Jupitrr AI Video Editor.

When to reach for it

Reels, TikTok, and Shorts

Captions keep viewers watching with the sound off.

LinkedIn video posts

Most LinkedIn video plays silently in the feed.

Quick client updates

Add captions to a short recorded message before sending.

Checking caption placement

Test size and position on a short clip before captioning a full video.

Frequently asked questions

Is the auto subtitle generator free?

Yes, for videos under 60 seconds, up to three videos a day. It is part of the Jupitrr Free Video Toolkit. For longer videos and unlimited use, sign up for Jupitrr.

Why is there a 60 second limit?

Speech detection runs on a paid transcription service. Keeping free videos short lets us keep the tool free. Videos longer than 60 seconds are rejected before upload.

Is my video uploaded?

Yes, once. The file is uploaded to a private storage location under a per-job key so the transcription service can read it. It is used only for transcription and is not shown anywhere public. The captions are then drawn onto the video in your browser, so the subtitled export never leaves your device.

Can I edit the captions before exporting?

Yes. Each caption line is editable. Click a timestamp to jump the preview to that moment, fix the text, then burn in or download the SRT.

What do the captions look like?

Bold white text with a black outline, the style most TikTok and Instagram captions use, centered near the bottom of the frame. You can change the font size and the position from the bottom. Lines are short, up to four words, so they read at a glance.

What languages are supported?

The language is detected automatically. English gives the best results. Other major languages are supported by the transcription service, with accuracy varying by language and audio quality.

What do I get at the end?

An MP4 with captions burned in at the original resolution, capped at 1920 pixels on the long side, and an optional SRT file with the same timings for YouTube, LinkedIn, or your editor.

What is Jupitrr AI?

Jupitrr is the AI video editor for coaches and consultants. The full editor adds animated caption styles, filler-word removal, B-roll, and one-click publishing. See the AI subtitle generator feature page for the complete version of this tool.

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