Every account gets 10 minutes of transcription each calendar month, no card needed. Longer videos use a prepaid minute pack, which stays valid for 12 months.

Do I need to install anything?

No. Everything happens in the browser. Upload the MP4, wait for the email, download the files.

Which languages are supported?

The spoken language is detected automatically, so there is nothing to configure. Most widely spoken languages are supported.

What happens to my video?

It is stored in the EU, used only to make your subtitles, and deleted automatically after about a day. Keep your original.

Can I edit the subtitles?

The SRT file is plain text, so any text editor works for fixing a word or a name. An in-browser editor is coming.

Add subtitles to an MP4 video online, free

An MP4 is the most common video file there is, and adding subtitles to one used to mean either typing them by hand or learning a video editor. ToneLark does the transcription for you: upload the file, and a few minutes later you have subtitles timed to the speech, in whichever form you need.

Two ways to add subtitles to an MP4

A subtitle file next to the video. You get an SRT or VTT file. Players, editors and platforms such as YouTube show the text on top of the video, and viewers can turn it off. The MP4 itself is unchanged. This is the right choice for YouTube, Vimeo, course platforms and your own website.

Captions burned into the picture. You get a new MP4 with the words drawn into the frames, with the spoken word highlighted as it is said. The captions can never be switched off and play everywhere, including Instagram, TikTok and places that ignore subtitle files. The original file is untouched.

ToneLark gives you both from one upload.

How to add subtitles to an MP4

Create a free account. Email or Google sign-in, no card.
Upload the MP4. Drag it onto the dashboard. Files up to 2 GB go straight to secure storage in the EU.
Wait a few minutes. The spoken language is detected and the speech is turned into text with precise timecodes. You get an email when it is done, so you can close the tab.
Download the subtitles. Pick SRT, VTT, or both. Use the file in your editor, on YouTube, or on your website.
Optionally, burn them in. Click Burn in and download a new MP4 with the captions in the picture. Videos up to 10 minutes, output up to 1080p.

What you get

Accurate timing. Every line starts and ends with the speech, down to the millisecond.
SRT and VTT. The two formats that every editor, player and platform accepts. Not sure which one? See SRT vs VTT.
Automatic language detection. No menus to pick from.
Word-by-word highlighting on burned-in captions, the style used on short-form social video.
Email when ready. No need to watch a progress bar.

Free minutes and packs

Every account gets 10 free transcription minutes per calendar month. A file has to fit in the minutes you have left; nothing is transcribed partially. If you need more, prepaid minute packs are valid for 12 months and are only used after the free minutes. Burning captions in does not use any minutes.

Tips for a good result

Upload the final cut. Trimming the video after transcription puts the subtitles out of sync.
Clear audio with one speaker at a time transcribes best. See how to get accurate automatic subtitles.
Read the subtitles through once. Names and acronyms are the usual words to correct.

Other formats

MP4 is just the most common case. The same steps work for MOV, MKV, WebM and audio-only files such as MP3, M4A and WAV. If the file plays on your computer, it almost certainly works here.