How do I generate subtitles automatically?

Sign up for free, upload your video or audio file, and FlowSub automatically generates accurate subtitles using OpenAI Whisper AI. The process usually takes 1–3 minutes. Download in SRT, VTT, ASS, or TXT format.

Is FlowSub free to use?

Starter ($8.99/mo) covers full transcription + FFmpeg tools. Pro ($16.99/mo) unlocks all AI generation: voice, music, image, video. Elite ($29.99/mo) includes everything with double the credits.

What video and audio formats are supported?

FlowSub supports MP4, MKV, MOV, AVI, WebM (video) and MP3, WAV, M4A, OGG (audio). Maximum file size is 500 MB.

How accurate is AI subtitle generation?

FlowSub uses OpenAI Whisper, achieving near human-level accuracy on clear audio. Accuracy depends on audio quality, speaker clarity, and background noise.

Can I get subtitles in multiple languages?

Yes. Whisper supports 29+ languages and auto-detects the spoken language. Pro users can also translate subtitles into any language on demand.

What subtitle formats does FlowSub export?

SRT (most compatible), VTT (web standard), ASS (advanced styling, Pro), and TXT (plain transcript). All formats generated with every transcription.

Free — No Sign-Up Required

Burn Subtitles into MP4

Hardcode SRT, VTT, or ASS subtitles directly into your MP4 video. No re-encoding step needed. Powered by FFmpeg — same engine used by Netflix.

No credit cardFirst file freeNo watermark500 MB free

Drop your file here

or click to browse

Subtitle: SRT, VTT, ASS, TXT, CSV · Video: MP4, MKV, WebM, MOV · Audio: MP3, WAV, AAC, FLAC · Free, no sign-up

⚡ Under 3 minutes🔒 No watermark, ever💰 8× cheaper than Veed✅ No sign-up for first file

How to use this tool

Three easy steps. No sign-up needed for your first file.

Upload your MP4

Drop your video file — up to 500 MB. Also works with MKV, MOV, WebM.

Upload your SRT/VTT

Attach your subtitle file. Accepts SRT, VTT, ASS, and raw TXT.

Download rendered video

FFmpeg burns subtitles directly into the video stream. Download your MP4 with hardcoded captions.

Frequently asked questions

What does 'burn subtitles' mean?

Burning subtitles means permanently encoding the subtitle text into the video pixels. Unlike soft subtitles (which can be toggled on/off), burned subtitles are always visible and work on any player, including Instagram, TikTok, and Discord.

Which subtitle formats are supported?

SRT, VTT, ASS, and plain TXT files. Max subtitle file size is 10 MB.

Can I customize the font and position?

Currently we use default styling optimized for readability. Custom font, size, color, and positioning controls are available on the Starter plan ($8.99/mo).

Does burning subtitles reduce video quality?

No. We use FFmpeg's libx264 with CRF 18 for near-lossless quality. The subtitle overlay is rendered at full resolution with no quality degradation.

How fast is it?

A 10-minute 1080p video with subtitles processes in about 90 seconds. Processing time scales linearly with video duration and resolution.

Is there a watermark on the output?

No. Unlike Veed and Kapwing, FlowSub never adds watermarks — not on the free tier, not ever.

Related free tools

Add Subtitles to Video

Add subtitles to any video — free and with zero watermarks. Unlike Veed and Kapwing, we never brand your content. Upload video + SRT, download captioned video.

Try free →

Audio Noise Remover

Remove background noise from audio and video files. FFT-based denoising eliminates fan hum, AC noise, street sounds, and static. Free, no sign-up.

Try free →

Change Video Resolution

Resize video resolution online — 4K to 1080p, 1080p to 720p, or any custom dimensions. Free, no watermark, no sign-up.

Try free →

Compress Video

Compress video files online without losing noticeable quality. Reduce MP4, MKV, MOV by up to 85%. Free, no watermark, no sign-up.

Try free →

Compress Video for Discord

Compress any video to fit Discord's 10 MB file limit. No quality guessing — we target exact file size with smart bitrate adjustment.

Try free →

Extract Subtitles from MP4

Extract subtitle tracks from MP4 video — or generate SRT from audio if none exist. Download as SRT, VTT, TXT. Free, no ads, no watermark.

Try free →

Ready to use Burn Subtitles into MP4?

First file free — no sign-up. Create a free account to unlock all features, larger files, and 5 free credits.

Burn Subtitles Free ← Back to all free tools

Free — No Sign-Up Required

Burn Subtitles into MP4

Hardcode SRT, VTT, or ASS subtitles directly into your MP4 video. No re-encoding step needed. Powered by FFmpeg — same engine used by Netflix.

No credit cardFirst file freeNo watermark500 MB free

Drop your file here

or click to browse

Subtitle: SRT, VTT, ASS, TXT, CSV · Video: MP4, MKV, WebM, MOV · Audio: MP3, WAV, AAC, FLAC · Free, no sign-up

⚡ Under 3 minutes🔒 No watermark, ever💰 8× cheaper than Veed✅ No sign-up for first file

How to use this tool

Three easy steps. No sign-up needed for your first file.

Upload your MP4

Drop your video file — up to 500 MB. Also works with MKV, MOV, WebM.

Upload your SRT/VTT

Attach your subtitle file. Accepts SRT, VTT, ASS, and raw TXT.

Download rendered video

FFmpeg burns subtitles directly into the video stream. Download your MP4 with hardcoded captions.

Frequently asked questions

What does 'burn subtitles' mean?

Which subtitle formats are supported?

SRT, VTT, ASS, and plain TXT files. Max subtitle file size is 10 MB.

Can I customize the font and position?

Currently we use default styling optimized for readability. Custom font, size, color, and positioning controls are available on the Starter plan ($8.99/mo).

Does burning subtitles reduce video quality?

No. We use FFmpeg's libx264 with CRF 18 for near-lossless quality. The subtitle overlay is rendered at full resolution with no quality degradation.

How fast is it?

A 10-minute 1080p video with subtitles processes in about 90 seconds. Processing time scales linearly with video duration and resolution.

Is there a watermark on the output?

No. Unlike Veed and Kapwing, FlowSub never adds watermarks — not on the free tier, not ever.

Related free tools

Add Subtitles to Video

Add subtitles to any video — free and with zero watermarks. Unlike Veed and Kapwing, we never brand your content. Upload video + SRT, download captioned video.

Try free →

Audio Noise Remover

Remove background noise from audio and video files. FFT-based denoising eliminates fan hum, AC noise, street sounds, and static. Free, no sign-up.

Try free →

Change Video Resolution

Resize video resolution online — 4K to 1080p, 1080p to 720p, or any custom dimensions. Free, no watermark, no sign-up.

Try free →

Compress Video

Compress video files online without losing noticeable quality. Reduce MP4, MKV, MOV by up to 85%. Free, no watermark, no sign-up.

Try free →

Compress Video for Discord

Compress any video to fit Discord's 10 MB file limit. No quality guessing — we target exact file size with smart bitrate adjustment.

Try free →

Extract Subtitles from MP4

Extract subtitle tracks from MP4 video — or generate SRT from audio if none exist. Download as SRT, VTT, TXT. Free, no ads, no watermark.

Try free →

Ready to use Burn Subtitles into MP4?

First file free — no sign-up. Create a free account to unlock all features, larger files, and 5 free credits.

Burn Subtitles Free ← Back to all free tools