Rankings
Review
Async Flash v1.5 is a well-balanced TTS solution for applications requiring high speed and low cost. It is well-suited for startups, SMBs, and automation teams, but not intended for projects demanding studio-grade quality or complex multilingual support.
Strengths
- Natural, clear voice quality that meets high standards for commercial applications
- Fast processing speed driven by the Flash architecture, well-suited for real-time processing
- Competitive pricing compared to top-tier TTS models, maximizing ROI for startups
Weaknesses
- Lacks the nuance and subtle emotional range of top-3 ranked models
- Limited language and accent support, lacking broad coverage for diverse markets
- Limited advanced features (custom voices, style controls)
Use cases
Guides & videos
Async Flash v1.5 is a premium text-to-speech (TTS) model from Async (an AI audio/video content platform, formerly Podcastle). Access it via the Async Voice API by sending a POST request to `https://api.async.com/text_to_speech` with `model_id`, `transcript`, and voice configuration parameters. It supports two modes: WebSocket (real-time streaming, low latency—recommended for interactive voice agents) and standard HTTP (simpler, ideal for batch synthesis). The model excels at handling non-standard words like numbers, dates, currencies, and abbreviations without requiring manual text preprocessing.