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

Speed Changer

Speed up or slow down video and audio in sync. Range: 0.25x to 4.0x.

No credit cardFirst file freeNo watermark500 MB free

Drop your file here

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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 video

Any video format. Up to 500 MB with account.

Choose speed

0.25x to 4.0x. Audio stays in sync with video.

Download adjusted video

Perfect for timelapses, slow-motion, or speed-watching.

Frequently asked questions

Does changing speed affect audio?

Yes — audio and video stay perfectly in sync. Slowing down lowers pitch, speeding up raises it (no pitch correction on free tier).

What speed range is supported?

0.25x (quarter speed) to 4.0x (quadruple speed) in 0.25x increments.

Will the video look smooth at non-standard speeds?

We use frame blending for smooth output at all speeds. Extreme slowdowns (0.25x) may appear slightly choppy.

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Ready to use Speed Changer?

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

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