Caption Studio

Upload a video or audio file and get SRT, VTT and ASS subtitles, a filler/silence cut list, and a burned-in MP4 with one of 12 caption presets. Fix recognition mistakes in the editor and re-burn for free. Everything runs on the Video Subtitle & Transcript API with your own RapidAPI key. Usage is billed to your RapidAPI plan exactly as if you had called the API yourself.

1. Your RapidAPI key

Remember on this device

Your key is used only inside this browser tab to call RapidAPI directly. It is never sent to or stored on yosuga.dev servers. Without "Remember", it is cleared when you close the tab.

No key yet? Subscribe to the BASIC plan (free, 30 minutes of media per month, 10 minutes per file), then copy the key from the API's Endpoints page or from RapidAPI Console → Applications.

2. Create a job

Video or audio file or a public media URL

Direct links to a media file only. YouTube/TikTok pages and Google Drive or Dropbox share links are web pages and will fail; upload the file instead (Drive direct form: drive.google.com/uc?export=download&id=FILE_ID, Dropbox: dl=1).

Language

Transcript

Orientation

Caption preset

Position

Vocabulary hints (comma-separated names and terms) Title (used by the title_top preset) Highlight color (karaoke_highlight, keyword_color)

Set #FFD400 (default)

Burned-in MP4 (slower) Cut list

Preset preview PNG or 5-second MP4

Preset

Orientation

Sample text

Previews use the language selected above. BASIC allows 20 previews per day; paid plans are unlimited.

History this browser only

No jobs yet.

Create a job to see results here. A 10-minute video usually takes 1–2 minutes; burn-in adds rendering time.

Available after a job with "Burned-in MP4" completes.

No job yet.

After a job completes, fix recognition mistakes here and burn the corrected captions into the same video.

No job yet.

Everything Caption Studio does is a plain HTTPS call. The same job as a cURL command (replace the key), plus ready-made automations:

API page on RapidAPI (endpoints, plans, test console)
OpenAPI 3.1 specification
n8n workflow template (JSON): video URL and style in a form, captioned MP4 out (paste the caption_style you tuned here into its Create captioning job node)
n8n workflow template: video URL in, SRT file out
n8n workflow template: transcribe, fix names with a find-and-replace list, re-burn for free
Quick start on the home page