Why burn captions in instead of using the app's own captions?

The built-in captions on TikTok and Instagram are tied to that platform, often unedited, and can be hidden by the viewer. Burned-in captions look the same everywhere and let you post one file to every platform.

Does it work with vertical 9:16 video?

Yes. The captions are placed for the frame you upload, vertical or horizontal.

What is word highlighting?

The word being spoken is shown in a different colour as it is said, the style common on short-form video. The timing comes from word-level transcription, so it follows the voice exactly.

How long can the video be?

Up to 10 minutes for burned-in captions, which covers every short-form format. Output is up to 1080p.

Captions for TikTok, Reels and Shorts with word highlighting

Most people watch short-form video with the sound off, at least until something makes them turn it on. Captions are that something. Clips with on-screen text are watched longer and finished more often, and the caption style that works best is the one you have seen a thousand times: a few words at a time, big and centred, with the spoken word lit up as it is said.

ToneLark makes that style automatically from your clip.

How to caption a clip for TikTok, Reels or Shorts

Export the final cut from your editor or phone, vertical (9:16) or whatever the platform wants. Captions are timed to this exact file, so cut first, caption last.
Upload it to ToneLark. Create a free account if you do not have one. Files up to 2 GB.
Wait for the email. The speech is transcribed word by word, with the language detected automatically.
Check the words. Download the SRT and fix a name if needed. Burned-in text cannot be edited afterwards.
Click Burn in and download the captioned MP4 when the next email arrives.
Post the same file to TikTok, Instagram and YouTube Shorts. No per-platform caption work.

What the captions look like

A few words per line, sized to read on a phone.
The word being spoken is highlighted, in sync with the voice.
Timing from word-level transcription, not from guessed subtitle cues.
Rendered into a new MP4 at up to 1080p. Your original clip is untouched.

Keep the text where people can see it

Each platform draws its own interface over the video: the caption and username at the bottom left, the like, comment and share buttons down the right side, and progress bars at the very bottom. Text placed there gets covered. Keep this in mind when you frame your shot: leave the lower part of the frame free of important visuals, and the captions will sit where they can be read.

Tips that make the biggest difference

Record with a close microphone. A lapel mic or earbuds beat the phone's built-in mic from a metre away. Clean audio means fewer words to fix.
Add music after captioning, or keep it well below the voice. Vocals in the music confuse any transcription.
One speaker at a time. Crosstalk cannot be captioned correctly.
Keep sentences short. They read better on a phone and highlight more cleanly.

More on this in how to get accurate automatic subtitles.

Should you also upload a subtitle file?

For YouTube Shorts, you can upload the SRT as well. YouTube indexes the text and viewers who prefer closed captions get them. TikTok and Instagram do not take subtitle files for Reels in a useful way, which is why burned-in captions are the norm there. ToneLark gives you both the SRT and the captioned video from one upload, so you can do whichever each platform needs.

Free minutes

Transcription uses 10 free minutes per calendar month, with prepaid packs for more. Burning the captions in does not use minutes. A 60-second clip costs one minute of transcription; the free allowance covers ten clips a month.