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The fastest way to add SLNG to an existing voice agent is to route your speech traffic through the platform. You keep your application code, your agent logic, and your call flow. You change where the speech requests go.

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How it works

The SLNG platform exposes one consistent base URL for every model. The path selects the service, provider, and model: 
https://api.slng.ai/v1/{tts|stt}/{provider}/{model}
Send your text-to-speech and speech-to-text requests there with your SLNG key, and you get caching, regional routing, and access to every supported provider behind a single integration.
1

Get an SLNG key

Create one at app.slng.ai/api-keys.
2

Point your requests at the gateway

Replace your provider’s endpoint with the SLNG platform URL and send your SLNG key in the Authorization header.
Text-to-speech
curl https://api.slng.ai/v1/tts/slng/deepgram/aura:2-en \
  -H "Authorization: Bearer SLNG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "model": "aura-2-thalia-en", "text": "Hello from SLNG!" }' \
  --output hello.wav
Speech-to-text
curl https://api.slng.ai/v1/stt/slng/deepgram/nova:3-en \
  -H "Authorization: Bearer SLNG_API_KEY" \
  -F "audio=@call.wav" \
  -F "language=en"
3

Keep your own provider key (optional)

Already have a provider contract? Add the X-Slng-Provider-Key header. Billing runs against your provider account, and output assembly still applies.BYOK applies to proxied providers, so use a provider path (not a slng/-hosted one). For example, Soniox:
curl https://api.slng.ai/v1/tts/soniox/tts-rt:v1 \
  -H "Authorization: Bearer SLNG_API_KEY" \
  -H "X-Slng-Provider-Key: YOUR_PROVIDER_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "text": "I brought my own key to the party.", "voice": "Adrian", "audio_format": "wav", "sample_rate": 24000 }' \
  --output hello.wav
See Bring your own key for supported providers, WebSocket setup, and billing.

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What you get

Output assembly

Repeated text-to-speech served from cache.

Regional execution

Pin traffic to a region with one header.

How it works

The execution path every turn takes between your app and the models.

Unified API

Switch providers by changing the path.

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Prefer a framework plugin?

If your agent runs on LiveKit, Cognigy, or Jambonz, use the native integration instead of calling the platform directly. See Voice platform integrations.