Free Index-Translate API for client subtitles: what to check

Use the free Index-Translate endpoint for public or low-stakes subtitles, and self-host the open weights before sending anything a client considers confidential. The page that advertises the endpoint calls it free and OpenAI-compatible, labels it an online demo, and publishes no rate limits, retention policy or service commitment that we could find on the pages read on 2026-10-04.

That does not make it unsafe, only unspecified. For a client transcript, unspecified is the thing to resolve first.

What does the vendor say about the free endpoint?

Bilibili's Index team released the Index-Translate family on September 30, 2026. The weights are Apache-2.0, which allows you to run them yourself. The hosted endpoint is a separate convenience on top of that.

What should you check before sending a transcript?

If any answer is no, run the 2B or 9B weights yourself. Both sizes are in the repository, and the burn step does not care where the text came from.

• Does your client contract allow third-party processing of the spoken content, even for a few lines?
• Is the transcript already public, such as a published video? Then the privacy question mostly disappears.
• Can you strip names, numbers and addresses from the cues first and restore them after translation?
• Do you have a fallback if the demo endpoint is slow or gone mid-project?

What does the Sume side see?

Sume's video captions endpoint receives two things: a public HTTPS video_url and your cues. Media inputs says localhost, private-network, non-HTTPS and signed or private URLs are rejected, so the clip itself has to be fetchable. That is a different exposure from the transcript sent to a translation endpoint, and worth deciding separately.

A standalone caption job is priced at $0.20 for videos up to 60 seconds under the current estimate. Cues are capped at 200 per request, 400 characters each, within 60 seconds.

A workable policy

Use the free endpoint for your own channel's content and for pilots. For client work, either self-host or get written approval for the hosted endpoint, and keep a record of which one translated which cues. The cue-translation recipe in this walkthrough works the same with either source of translated text.