Add Subtitles to Video Online, Free

To add subtitles to video online free, upload your clip to EchoWave, click Auto-Subtitle to transcribe the speech automatically, then edit any wording and restyle the captions. Export a burned-in MP4 or download an SRT, VTT, or TXT file. Everything runs in your browser, with no signup and no software to install.

AI subtitle generator: captions in seconds

EchoWave's auto subtitle generator turns the speech in your video into a fully timed transcript in seconds. Upload your clip, click Auto-Subtitle, and this video subtitle generator listens to the audio and writes synced caption lines for you. There is no manual typing, no signup, and no software to install, and it stays a free subtitle generator however many videos you subtitle.

The AI transcribes speech across a wide range of accents, mic quality, and background conditions, then breaks the text into short, readable lines timed to match the pace of the dialogue. That is the difference between a transcript and real subtitles: the wording is split and timed so each line appears and disappears at the right moment.

Edit the AI captions in seconds

No automatic subtitle generator is perfect, especially with names, jargon, or crosstalk, so EchoWave keeps you in control. Review the generated captions, correct any words, merge two short lines into one or split a long line in two, and nudge the timing a few frames either way. It is the same editor you use to add subtitles to a video manually, so switching between auto and hand editing is instant.

Already have a script or a caption file? You can skip transcription entirely. Type your subtitles in directly, or upload an existing SRT or VTT file and EchoWave will lay the lines onto the timeline ready to style and export.

Translate captions into 100+ languages

Auto-transcription does the heavy lifting on the original language, but you do not have to stop there. Once the speech is transcribed, you can translate the captions into more than 100 languages in a single click, which is what turns a clip aimed at one audience into a video that reaches viewers worldwide.

This is the practical reason subtitles matter for reach. A captioned, translated video surfaces for searches in other languages, is far more shareable across regions, and reaches people who would otherwise scroll straight past. If you know the languages your audience speaks, add a subtitle track for each one and export a version per language, or attach multiple caption files to platforms that support them.

For incoming foreign-language footage, the same flow works in reverse: transcribe the original audio, translate the lines into English (or any target language), then review the wording before you export. It is a quick way to make interviews, lectures, or clips from abroad watchable for your own audience.

Style and animate your captions

Auto-generated captions are the starting point, not the finish line. In EchoWave you can restyle every caption to match your brand and the platform you are posting to, all without retyping a word.

Fonts, colors, and backgrounds

Pick from a large font library, set the fill and stroke (outline) color, and add a backing box or drop shadow so text stays legible over busy footage. Resize the type so it reads cleanly on a phone screen, and drag the captions anywhere on the canvas: low for a classic look, centered for impact, or tucked inside the safe zone so platform buttons and usernames do not cover them.

Animated, word-by-word captions

Motion keeps captions engaging. Use fade, slide, and pop effects, or highlight each word as it is spoken for the punchy karaoke style that performs well on TikTok, Reels, and Shorts. Keep motion subtle for tutorials and explainers, and turn it up for social promos where you want the eye to stay on the text.

Reusable caption styles

Dial in one look, then reuse it across every clip so your videos stay consistent. Because you are styling the captions you already generated, applying your house style to a new video takes seconds rather than a fresh setup each time.

Burned-in MP4 vs SRT, VTT, and TXT files

When you add subtitles to a video in EchoWave, you choose how they leave the editor, and the right answer depends on where the clip is going.

Burned-in (hardcoded) captions

Burned-in subtitles are drawn permanently onto the video frames, so they are always visible no matter where the file is played, re-uploaded, or re-shared. This is the best option for TikTok, Instagram Reels, YouTube Shorts, and any feed where captions need to show by default. A burned-in MP4 keeps your exact font, color, position, and animation, and it is the only way to guarantee captions appear on platforms that ignore separate subtitle tracks.

SRT, VTT, and TXT files

If you want captions viewers can toggle on or off, download a soft subtitle file instead. An SRT or VTT file uploads alongside your video on YouTube, Vimeo, and similar platforms, where the player overlays it and viewers control whether it shows. You can also export a plain TXT transcript to reuse as show notes, a blog post, or a description, or to feed search engines indexable text from your video.

Subtitles vs captions: the difference

Subtitles assume the viewer can hear the audio and focus on transcribing or translating the spoken dialogue. Closed captions go further: they also note sound effects, music, and who is speaking, which makes them an accessibility feature for deaf and hard-of-hearing viewers. EchoWave produces either, so you can caption dialogue for reach or write full closed captions for accessibility.

Why add subtitles to video: TikTok, Reels, Shorts, YouTube, and accessibility

Captions are one of the few edits that grow reach, engagement, and accessibility at the same time, which is why nearly every successful creator and brand reaches for a subtitle generator for video. Add captions to video once and you serve viewers on mute, in other languages, and with hearing loss all at the same time.

Social video watched on mute

The majority of feed videos autoplay without sound, so captions are what keep viewers watching past the first second. Add bold, animated subtitles to TikTok, Instagram Reels, YouTube Shorts, and Facebook clips so the message reads on silent autoplay. For vertical 9:16 video, keep captions clear of the bottom third where the caption text, music tag, and buttons sit; for square 1:1 and landscape 16:9, the lower-center band is usually safe.

YouTube and long-form video

Upload an SRT to YouTube as a toggleable caption track, or burn captions into clips, ads, and Shorts. YouTube also reads your caption text, which gives the video more indexable content and can help it surface for additional searches. For interviews and webinars, a TXT transcript doubles as searchable show notes.

Accessibility and inclusion

Many millions of viewers are deaf or hard of hearing. Closed captions that include speaker labels and sound cues let everyone follow along, signal that your content is built for everyone, and widen your potential audience at no extra production cost.

Quiet and noisy rooms

Plenty of people just prefer to read along: on a commute, in a shared office, in bed next to someone, or in a loud cafe. Subtitles make your video watchable in any setting, which means fewer dropped views and a message that sticks.

Supported formats, specs, and device support

EchoWave reads the common video containers and codecs you are likely to have, including MP4 (H.264), MOV, WebM, MKV, and AVI. When you transcribe, the tool works from the audio track, so a clean voice recording produces the most accurate captions; heavy music or overlapping speakers will need a little more editing afterwards.

On export you can keep your source aspect ratio or work in the standard social ratios: 9:16 for TikTok, Reels, and Shorts, 1:1 for square feed posts, and 16:9 for YouTube and landscape. Caption files export as SRT, VTT, or TXT, and burned-in captions render into a standard MP4 that uploads anywhere.

Because the editor runs in the browser, it works the same on Windows, macOS, ChromeOS, and Linux, and on iPhone, iPad, and Android in any modern browser such as Chrome, Edge, Safari, or Firefox. There is nothing to download. Your video uploads to EchoWave for processing and export, and your files stay private to your account.

How to add subtitles with FFmpeg

If you prefer the command line, FFmpeg can add subtitles too. Create a .srt subtitle file, then mux it in as a soft (toggleable) track:

ffmpeg -i input.mp4 -i subtitles.srt -c copy -c:s mov_text output.mp4

To burn the subtitles permanently into the frames instead, use the subtitles filter:

ffmpeg -i input.mp4 -vf subtitles=subtitles.srt output.mp4

FFmpeg is powerful but command-line only, with no preview, no styling, and no transcription. EchoWave gives you the same SRT and VTT export plus an AI auto subtitle generator and a visual editor, free in your browser.