Add captions to a video, free

How to add captions to a video

1. 1. Add the video

   Upload the video file in the app (up to 5 GB), or paste a YouTube, X or Google Drive link. FastClip reads the speech and writes the transcript.

2. 2. Choose the part and the frame

   A captioned clip is up to 5 minutes. For a short video, set the start to 0:00 and the end to the last second. For a longer video, pick the part in the transcript or on the timeline. Keep the original frame, or turn on the 9:16 crop for Shorts, Reels and TikTok.

3. 3. Check the words

   Read the transcript and correct any word. Look at names, numbers and product words first. The captions follow your corrections.

4. 4. Style the captions and download

   Choose one of six presets, or set the size, position, colors, background, animation and words per line. Then finish the clip, download the MP4, or post it to Instagram or X from FastClip.

What the captions are, and what they are not

FastClip burns the captions into the picture. These are the facts:

• Burned in. The words are part of the video. A viewer cannot turn them off, and they look the same in every app.
• Word-timed. Each word shows when it is spoken. FastClip detects the spoken language among 35 languages.
• Automatic, so check them. They come from speech recognition. Correct what it got wrong before you finish.
• One file, no translation. The result is one MP4. FastClip does not give you a separate caption file, and it does not translate captions into another language.

In practice: burned-in captions work with the sound off in every app. Some apps also have their own caption settings. Use those too when you can. Our captions guide compares the two.

What makes captions easy to read

From YouTube Help on automatic captions (read October 15, 2026), the W3C Web Accessibility Initiative (captions, read October 14, 2026), WCAG 2.2 (contrast) and the BBC Subtitle Guidelines (read September 28, 2026):

• Always check automatic captions. YouTube says its automatic captions come from machine learning, so “the quality of the captions may vary”, and tells you to review and edit what was not transcribed properly.
• Accuracy decides. W3C says automatic captions meet users’ needs only if they are confirmed to be fully accurate.
• Short lines. The BBC’s guide is about 25 characters a line and up to three lines on vertical video.
• Contrast. WCAG asks for at least 4.5:1 between the text and its background, and 3:1 for large text.

In practice: use few words a line, a strong background or outline, and a position above the bottom third. More in the captions guide and in our caption templates.

Which videos this fits

One clip is up to 5 minutes, so this fits a video of that length: a talk excerpt, a tutorial step, a product demo, an interview answer, or a video you shot on a phone. A longer video becomes several clips, one for each part, and each finished clip counts toward your plan. FastClip does not caption a one-hour video in one go.

Questions

More ways to prepare a video

Need the frame to fit a phone? See horizontal to vertical video and video to Shorts. Captioning a podcast? See the podcast clip maker. For caption looks, see the clip templates.