Confirm the scope before changing providers
Capslane v1 replaces the YouTube transcript workflow. It does not replace Supadata endpoints for other networks, web extraction or unrelated metadata. Keep those calls unchanged until an equivalent product exists.
Map the request and response
The Capslane request accepts a YouTube URL or ID, language, text mode, chunk size and the native, auto or generate path.
curl 'https://capslane.com/v1/transcript?url=VIDEO_ID&lang=en&text=false&mode=auto' \
-H 'x-api-key: YOUR_API_KEY'Offsets and durations use milliseconds. Generated work returns HTTP 202 and a job ID. Do not assume that a generated transcript is synchronous.
Test a representative corpus
Include manual captions, automatic captions, missing captions, multiple languages, cache hits, unavailable videos and the longest duration your product accepts. Compare usable text and timing, not only the status code.
Run shadow traffic without double-writing product state
Send a bounded sample to both providers, record result categories and compare them offline. Do not let both responses trigger user notifications or downstream jobs. Remove transcript text from technical comparison logs.
Cut over by mode and retain rollback
Move cache hits and native requests first, then generated work. Keep request IDs, failure rates and latency visible. Retain a provider switch until the representative corpus and real traffic remain stable.