# Auto Captions & Subtitle Generator: Add Captions to Video Generate auto captions and add subtitles to video with word-by-word highlights, custom fonts, and SRT downloads. ## How it works 1. Add a video with speech. Audo writes down every word and when it's said, in the spoken language you choose or the one it hears. 2. Pick a caption style, then in the editor fix any word, highlight the ones that matter, and drag the subtitles where they fit your picture. 3. Press Export to download the captioned MP4 video, or download the captions as SRT and VTT subtitle files. ## Word-timed auto captions and subtitles that fit your picture Audo's auto captions and video subtitle generator transcribes and captions MP4, MOV, MKV, WebM, and AVI videos up to 2 GB across 60 languages, with the first 2 minutes free, 3 times a day, and no sign-up. Because most social videos start playing on mute, readable captions with word-by-word timing keep viewers following along before they ever tap for sound. In the browser editor, you can preview 36 caption presets live on the canvas, customize the font, stroke, shadow, and active-word highlight, fix any transcribed name or term, and export both a burned-in H.264 MP4 and standalone SRT or VTT subtitle files. Tool: Add captions (`add_captions`). Price: 4 credits a minute — $0.04/min ($2.40/hr), with no subscription — of input for whole files, charged only when a job succeeds. ## Free API ```bash curl -F file=@video.mp4 https://audo.ai/api/try/add-captions -D response.headers -o response.body ``` Read response.headers and response.body before naming media. Handle 202, 200 JSON and errors with the complete response client at https://audo.ai/docs/api?utm_source=markdown&utm_medium=agent#responses. Free for the first 2 minutes of each file, 3 times a day per person, with no key or account. Uploads up to 10 GB, 2 at once from one address. The response is the result itself; a job that runs longer than about 30 seconds returns 202 with a link to check on it. With an API key (`-H "Authorization: Bearer $AUDO_API_KEY"`), omitting free runs the whole file with credits if the balance covers it, otherwise the free portion if quota remains. Set free=true to prohibit spending; for paid whole files use free=false with an approved positive max_credits. A free result cut short comes with finishUrl (and the Audo-Finish-Url header when the response is the file itself): give it to the person, who pays there (from $5, no sign-up), and the whole file runs; keep checking the status link, whose finishedBy names the whole-file job and its own status link. Details: https://audo.ai/docs/api.md ## Options Form fields with the same names as the MCP tool's inputs: - `captions`: Caption document v1: preset plus style/layout overrides, language, optional timed words, edited text, and outputs. Times are milliseconds; position and font sizes are fractions of the video frame. ## Languages 60 languages, detected automatically: `af` Afrikaans, `ar` Arabic, `hy` Armenian, `as` Assamese, `az` Azerbaijani, `bn` Bengali, `bs` Bosnian, `bg` Bulgarian, `yue` Cantonese, `ca` Catalan, `zh` Chinese (Simplified), `cs` Czech, `da` Danish, `nl` Dutch, `en` English, `et` Estonian, `fil` Filipino, `fi` Finnish, `fr` French, `gl` Galician, `de` German, `el` Greek, `gu` Gujarati, `he` Hebrew, `hi` Hindi, `hu` Hungarian, `is` Icelandic, `id` Indonesian, `it` Italian, `ja` Japanese, `kn` Kannada, `kk` Kazakh, `ko` Korean, `lv` Latvian, `lt` Lithuanian, `mk` Macedonian, `ms` Malay, `ml` Malayalam, `mr` Marathi, `ne` Nepali, `nb` Norwegian Bokmål, `or` Odia, `fa` Persian, `pl` Polish, `pt` Portuguese, `pa` Punjabi, `ro` Romanian, `ru` Russian, `sk` Slovak, `sl` Slovenian, `es` Spanish, `sw` Swahili, `sv` Swedish, `ta` Tamil, `te` Telugu, `th` Thai, `tr` Turkish, `uk` Ukrainian, `ur` Urdu, `vi` Vietnamese. ## From an assistant (MCP) Add https://audo.ai/mcp and sign in (setup for each assistant: https://audo.ai/setup.md). The tool is `add_captions`: > Adds styled captions to video. captions.words overrides transcript_file_id words; captions.text aligns edits. Use 36 presets or style_id with style/layout overrides. auto_keywords, auto_emoji and translate_to add 1 credit/minute once; bilingual keeps both languages. It costs 4 credits a minute, or 2 with supplied words or 1 with transcript_file_id, charged only if the job succeeds. Exports MP4, transparent overlay, SRT/VTT/ASS/TXT and transcript/caption JSON. Returns download links or job_id for get_job. list_caption_presets lists looks. Example: "Add karaoke captions to this video." ## Questions **Is it free?** Yes. Audo is free for the first 2 minutes of each file, 3 times a day, with no sign-up. Whole files are $0.04 a minute ($2.40 an hour), with no subscription — see pricing. **Are these captions burned into the video or separate subtitle files?** You can get both. When you export video, Audo burns the styled captions onto the picture so viewers see them even with sound off or on platforms without subtitle support. You can also download separate SRT and VTT subtitle files from the same project. **Can I highlight each word as it is spoken?** Yes. Audo timestamps every individual word and offers 36 preset looks—including karaoke fill, active word color, word box, pop-in, and one-word-at-a-time styles, plus classic two-line subtitles for interviews, lectures, and long-form videos. **Can I use this as a YouTube caption generator or TikTok subtitle generator?** Yes. Upload your MP4, MOV, or WebM video file (rather than a YouTube link), pick a vertical safe zone for TikTok, Reels, and Shorts or a landscape layout for YouTube, and export either the burned-in MP4 or the SRT/VTT files for YouTube Studio. **Where should I place subtitles on a vertical 9:16 video?** Leave room for faces in the center and platform buttons and descriptions along the bottom and right edge. Audo includes safe-zone overlays for Shorts, Reels, and TikTok so you can drag captions into the clear area. **Can I edit a misspelled word before rendering the video?** Yes. Audo transcribes your video first and opens the words over the live canvas preview in the editor. Fix any spelling, split or merge caption lines, or nudge word timing for free before you export the final MP4. **Can I save my own custom caption style?** Yes. Save style stores your font, colors, outline, background box, animation, and words-per-line under a name you choose, ready to reuse on your next video or via the API. ## More - Every tool: https://audo.ai/llms.txt - OpenAPI: https://audo.ai/api/openapi.json - This page for people: https://audo.ai/auto-captions?utm_source=markdown&utm_medium=agent