Provider Matrix

CompositeVoice supports 11 provider companies across 17 provider classes, plus 4 input/output providers for the 5-role pipeline. This page organizes them by company so you can see everything a single vendor offers.

Audio Input / Output (Pipeline I/O)

These providers handle the input and output roles in the 5-role pipeline. They are not tied to any vendor.

MicrophoneInput buffers audio frames in the input queue while the STT WebSocket connects, then flushes them in order — no audio is ever lost. BufferInput does the same for programmatic audio sources.

BrowserAudioOutput handles AudioContext resumption and buffers frames in the output queue during speaker setup. NullOutput discards all audio — use it for server-side pipelines where there are no speakers.

Multi-role providers like NativeSTT (input+stt) and NativeTTS (tts+output) cover multiple pipeline roles. When using them, you do not need separate input or output providers.

Deepgram

DeepgramSTT (V1/Nova) features: Interim results, smart formatting, auto-punctuation, speaker diarization, entity detection, keyword boosting, profanity filter, redaction (PCI/SSN), numerals conversion, VAD events, word-level timestamps, configurable endpointing, utterance buffering, multichannel transcription. Models: nova-3 (recommended), nova-3-medical, nova-2 (+ domain variants), nova (legacy).

DeepgramFlux (V2/Flux) features: Turn-based conversation model, eager end-of-turn detection (configurable thresholds: eot_threshold 0.5–0.9, eager_eot_threshold 0.3–0.9), end-of-turn timeout (eot_timeout_ms), keyterm support, word confidence scores. Events: StartOfTurn, EagerEndOfTurn, TurnResumed, EndOfTurn, Update. Models: flux-general-en. Only provider that supports the eager LLM pipeline.

TTS features: Real-time streaming synthesis, linear16/mulaw/alaw encoding, configurable sample rate (8–48 kHz), word-level timing metadata.

TTS models: Aura 2 (recommended — 40 English voices + 10 Spanish voices), Aura 1 (legacy — 12 English voices).

Guides: DeepgramSTT · DeepgramFlux · DeepgramTTS · Examples: 20, 21, 22, 23, 24

Anthropic

LLM features: Streaming via SSE, system prompts extracted to top-level system parameter (Anthropic API convention), maxTokens required (default 1024), AbortSignal cancellation for the eager pipeline, temperature and topP controls.

Models: claude-haiku-4-5 (fastest), claude-sonnet-4-6 (balanced), claude-opus-4-6 (most capable).

Guides: AnthropicLLM · Examples: 00, 30, 31

OpenAI

LLM features: GPT model family, streaming token generation, organizationId for multi-org accounts, temperature/topP/maxTokens controls.

LLM models: gpt-4o-mini, gpt-4o, gpt-4-turbo, gpt-3.5-turbo.

TTS features: 6 voices (alloy, echo, fable, onyx, nova, shimmer), quality/speed tradeoff via model selection (tts-1 fast, tts-1-hd quality), 5 output formats (mp3, opus, aac, flac, wav), speed control (0.25–4.0x), 4096 character limit per request, endpoint for Azure OpenAI compatibility.

Guides: OpenAILLM · OpenAITTS · Examples: 40, 41, 42

Groq

LLM features: Ultra-fast LPU-based inference (lowest latency of any cloud LLM), OpenAI-compatible API, groqApiKey convenience alias, wide range of open-source models.

Models: llama-3.3-70b-versatile, mixtral-8x7b-32768, gemma2-9b-it, llama-3.1-8b-instant.

Guides: GroqLLM · Examples: 60

Google Gemini

LLM features: OpenAI-compatible endpoint, geminiApiKey convenience alias, auto-configured base URL (generativelanguage.googleapis.com/v1beta/openai).

Models: gemini-2.0-flash, gemini-1.5-pro, gemini-1.5-flash.

Guides: GeminiLLM · Examples: 100

Mistral

LLM features: Strong multilingual support, OpenAI-compatible API, mistralApiKey convenience alias.

Models: mistral-small-latest, mistral-medium-latest, mistral-large-latest.

Guides: MistralLLM · Examples: 110

AssemblyAI

STT features: Interim results, word boosting for domain vocabulary, word-level timestamps and confidence, automatic reconnection with exponential backoff, base64-encoded audio, graceful terminate_session on disconnect, configurable sample rate.

Guides: AssemblyAISTT · Examples: 70

ElevenLabs

STT features: Scribe V2 Realtime (~150ms latency), 90+ languages with auto-detection, VAD and manual commit strategies, interim results (partial transcripts), word-level timestamps and confidence, base64-encoded audio, three auth methods (API key, proxy, single-use token), BCP 47 / ISO 639-1 / ISO 639-3 language code auto-mapping, configurable VAD sensitivity, previousText context, zero-retention mode.

TTS features: Voice cloning controls (stability 0–1, similarityBoost 0–1), BOS/EOS stream-input protocol, word-level alignment, 6 output formats (pcm_16000, pcm_22050, pcm_24000, pcm_44100, mp3_44100_128, ulaw_8000), multilingual models.

TTS models: eleven_turbo_v2_5 (fast), eleven_turbo_v2, eleven_multilingual_v2, eleven_monolingual_v1.

Guides: ElevenLabsSTT · ElevenLabsTTS · Examples: 80, 81

Cartesia

TTS features: Ultra-low-latency streaming, context-based streaming (context_id + continue flag preserves prosody across chunks), emotion controls (emotion_name:intensity tags), speed multiplier, 4 PCM encodings (s16le, f32le, mulaw, alaw), word-level timestamps, configurable sample rate.

Models: sonic-2 (latest, lowest latency), sonic, sonic-multilingual.

Guides: CartesiaTTS · Examples: 90

Browser Built-ins

STT features: Zero dependencies, works offline, 50+ languages via browser, continuous mode, interim results, maxAlternatives, startTimeout, managed audio (browser controls the microphone directly).

TTS features: Zero dependencies, works offline, voice enumeration via getAvailableVoices(), voice selection by name/language, rate/pitch/volume controls, pause/resume/cancel playback, runtime voice switching with setVoice(), managed audio (browser plays directly).

Limitations: NativeSTT requires Chromium (no Firefox). Both use managed audio — the SDK cannot access raw audio streams. No preflight signals. Best for prototyping.

Guides: NativeSTT · NativeTTS · Examples: 00

WebLLM (MLC AI)

LLM features: Fully offline after initial model download, all data stays in the browser, onLoadProgress callback for download UI, chatOpts for engine tuning, engine.interruptGenerate() abort support, no API keys needed.

Example models: Llama-3.2-1B-Instruct-q4f16_1-MLC (~500 MB), Phi-2-q4f16_1-MLC (~1.5 GB).

Guides: WebLLMLLM · Examples: 50

Feature comparison at a glance