Convert MP3 to VTT Captions
Upload an MP3 and get back a properly paced WebVTT file, ready to drop into an HTML5 <track> tag, a webinar replay, or a course platform that expects .vtt instead of .srt.
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Plenty of caption tools assume you're editing desktop video and only ever export SRT. But if you're publishing to a website, embedding a lecture recording in an LMS, or uploading a webinar replay to a platform that reads the WebVTT spec, SRT often gets rejected outright — you need a real .vtt file with the right header and cue formatting. Transkio transcribes your MP3 and exports it as WebVTT directly, so you're not stuck converting formats by hand afterward.
Upload the MP3 file itself — Transkio doesn't fetch audio from a URL, so grab the recording from your webinar host, recorder, or export tool first. From there, Transkio's speech-to-text engine transcribes the audio, times each line to the source recording, and paces the resulting captions into cues sized for on-screen reading before you export the finished .vtt file.
SRT Doesn't Work Everywhere WebVTT Does
WebVTT is the caption format the HTML5 <track> element actually expects, and it's what most web-embedded video players, some webinar hosting platforms, and a number of LMS or online-course tools require for uploaded captions. SRT is common in desktop editors like Premiere or Final Cut, but it isn't part of any web standard — plenty of browser-based players won't parse it, or will silently fail to display anything.
That mismatch shows up most with recorded audio: a webinar session, a course lecture, a podcast episode meant for a web page. You've got an MP3, but the destination wants captions in a format the file doesn't come in, and manually retyping timestamps into VTT syntax for a 45-minute recording isn't a reasonable use of anyone's afternoon.
Upload the MP3, Export WebVTT Directly
Transkio accepts MP3 (along with WAV, M4A, AAC, OGG, OPUS, and FLAC) and transcribes it with word-level timing. When you export, choose VTT and you get a standards-compliant .vtt file with cues split at natural word boundaries and kept within readable length and duration limits — no manual reflowing needed before it goes live on a page.
Every transcript is editable before export too: click any line to jump the player to that moment, fix a misheard word or name, or rename a speaker, and the changes carry through to your VTT export. Transkio's free plan includes 60 trial minutes and then 30 minutes a month, with VTT export available at every plan tier — no card required to start.
What You Get
See it work
See the Difference
A real example of how the same recording reads before and after Transkio.
Webinar clip, transcribed and captioned
ok so today were gonna go over uh the three main pricing tiers and uh what each one includes so lets jump right in
WEBVTT 00:00:00.000 --> 00:00:03.400 Okay, so today we're going to go over 00:00:03.400 --> 00:00:06.800 the three main pricing tiers and what each one includes. 00:00:06.800 --> 00:00:08.500 So let's jump right in.
Frequently asked questions
What's the actual difference between VTT and SRT?
WebVTT (.vtt) is the caption format defined by the W3C for use on the web — it's what the HTML5 <track> element reads natively in browsers. SRT (SubRip) predates the web standard and is more commonly used in desktop video editors. They look similar (timestamps plus text) but use different syntax, and many web players and some webinar or LMS platforms only accept one or the other.
Is VTT export available on the free plan?
Yes. VTT is included at every plan tier, including free — along with TXT and SRT. The free plan gives you 60 trial minutes, then 30 minutes per month, no card required.
Can I paste a link to my webinar recording instead of uploading the file?
No — Transkio works from an uploaded file or an in-browser recording, not a pasted URL. Export or download the audio from your webinar or recording platform first, then upload the MP3 directly.
Will the VTT captions be in a different language than the audio?
Transkio transcribes in the source language by default. Translated text transcripts are available starting on the Pro plan, but translation currently produces a translated text transcript only — not a translated VTT or SRT caption file.
How big of a file or how long of a recording can I upload?
Free accounts can upload files up to 100 MB. Paid plans raise those limits considerably — Ultra supports files up to roughly 8 GB and recording sessions as long as 8 hours, which comfortably covers a full-day webinar or lecture series.
Related Tools and Guides
MP3 to SRT
Need SRT instead — for a desktop video editor or a platform that expects SubRip files? Convert MP3 audio to SRT captions.
MP3 to Text
Just need a readable transcript, no caption timing? Convert MP3 audio straight to a text file.
Video Subtitle Generator
Working from a video file instead of extracted audio? Generate subtitles directly from your video upload.
Turn Your MP3 Into Web-Ready VTT Captions
Upload your webinar or lecture recording and export a properly paced WebVTT file in minutes. Free plan includes 60 trial minutes, no card required.
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