Voxtral Mini Playground for Prompt Testing

A Voxtral Mini transcription playground is a UI to test transcription prompts and run evals on audio-to-text outputs using Voxtral Mini—focused on accuracy, formatting, and consistency.

Prompt testing and evaluations for transcription: clean text, punctuation, speaker labels, timestamps, summaries, and repeatable checks across the same audio clips.

Yes. Bring your API keys. LangFast routes requests through our proxy.

To prevent abuse, apply fair-use limits, and let you save runs, reuse the same audio set for regression tests, and share results.

Word accuracy (at least by spot-checking), punctuation, capitalization, numbers/dates, and how well it handles accents, noise, and overlapping speech.

If the model supports it, yes. Evaluate whether speaker turns are consistent and whether labels drift across the same clip.

Yes. Prompt for timestamps and check whether they are stable and useful (not random or overly frequent).

Yes. Enforce output formats like paragraphs, bullets, “speaker: text” lines, or JSON segments—and measure how often formatting breaks.

Yes. Evaluate summary quality, missed decisions, and whether action items are specific and attributable.

Yes. Reuse a fixed audio set and rerun after prompt changes to see if transcription and post-processing quality improves or regresses.

Yes. Run the same clips side-by-side and compare accuracy, formatting, and speed across providers.

Yes—export to cURL/JS/JSON so your team can reproduce the exact call and parameters.

Yes. Save transcripts, keep prompt versions, and share links for review, editing, or stakeholder approval.

LangFast is free to use with some basic features. You need to provide your own API keys to run models and use the app. When you add your API keys, you pay the model provider (e.g., OpenAI) for the credits/tokens you use. LangFast premium features can be unlocked with a one-time purchase.

Wait for reset or add paid usage to continue running transcription evals.

It depends on clip length and model load. We route via a lightweight proxy; compare end-to-end time across models directly.

No. We don’t train on your prompts, audio, or transcripts. Sharing is opt-in and retention is configurable.

Requests route to model providers. See the Data & Privacy page for processing regions and details.

LangChain helps you build transcription workflows. LangFast helps you test prompts and evaluate output formats before you implement pipelines.

Those tools manage datasets, evals, and tracing inside workflows. LangFast is an interactive bench for quick transcription prompt testing and comparisons.