> ## Documentation Index
> Fetch the complete documentation index at: https://docs.responsivevoice.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Why ResponsiveVoice?

ResponsiveVoice is an open-source, TypeScript-first text-to-speech layer for the web. It is the integration and control layer between your site and one or more voice engines — browser-native, ResponsiveVoice's hosted voices, or premium providers you bring yourself.

> [!NOTE]
> ResponsiveVoice v2 is a complete rewrite of the original library —
> MIT-licensed, fully typed, and split into focused packages. Older reviews
> describing it as a fixed-price Web Speech API wrapper predate this release.

## What ResponsiveVoice gives you

- **Open source, MIT-licensed.** The client (`@responsivevoice/core`) is a drop-in replacement for the legacy `responsivevoice.js` — same `speak`/`cancel`/`pause`/`resume` API, now typed and tree-shakeable.
- **Browser-native with automatic fallback.** Uses the Web Speech API when the device has a matching voice, and falls back to hosted server voices when it doesn't — one API, consistent behavior across browsers.
- **100+ voices across 50+ languages**, fetched and cached at runtime, so the catalog improves without a package upgrade.
- **Bring Your Own Key (BYOK).** Route premium voices from **Google Cloud**, **Microsoft Azure**, and **OpenAI** through ResponsiveVoice using your own provider key — you keep the provider relationship and the per-character billing, and gain RV's browser integration, fallback, streaming, and player features on top.
- **Streaming playback.** HTTP audio or WebSocket, so speech starts before the full clip is ready.
- **Predictable pricing.** A free plan plus fixed-tier plans, instead of metering every character.
- **REST + WebSocket API** documented by an OpenAPI 3.1 specification, for server-side and non-browser use.

## How it compares

The premium providers below produce excellent neural audio. The distinction is that ResponsiveVoice is the **integration layer** — and with BYOK it can front those same providers rather than competing with them.

| Capability                | ResponsiveVoice                  | ElevenLabs                   | Azure / Google Cloud |
| ------------------------- | -------------------------------- | ---------------------------- | -------------------- |
| Open source (MIT)         | Yes                              | No                           | No                   |
| Drop-in browser script    | Yes                              | Via your own backend         | Via your own backend |
| Browser-native + fallback | Yes                              | Cloud only                   | Cloud only           |
| Premium neural voices     | Via BYOK (Azure, OpenAI, Google) | Native                       | Native               |
| Voice cloning             | No                               | Yes                          | Limited              |
| Pricing model             | Free plan + fixed tiers          | Per-character / subscription | Per-character        |
| Streaming                 | HTTP + WebSocket                 | Yes                          | Yes                  |

## When to choose what

- **Choose ResponsiveVoice** when you want a drop-in, open-source browser TTS with native-plus-fallback behavior, predictable pricing, and the option to bring premium provider voices via BYOK without re-architecting — read-aloud, accessibility, language learning, article narration, and announcements.
- **Choose a provider directly** when best-in-class voice cloning or maximum expressive realism is the product itself, and you're set up to manage the integration and per-character billing.

Many sites use both: ResponsiveVoice for the browser integration and player, with a premium provider supplied via BYOK for the voices.

## Next steps

- [Installation](/getting-started/installation/) — add the script or install from npm.
- [Voice Selection](/guides/voice-selection/) — filter and resolve voices.
- [REST API](/rest-api/) — server-side synthesis.