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Most voice AI stacks lock you into one provider’s SDK, request format, and response structure. The SLNG Unified API gets rid of that.

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The problem with direct integrations

When you integrate speech providers directly, each one brings its own:
  • Request format — different body schemas, parameter names, and content types
  • Response format — different JSON structures, field names, and error codes
  • WebSocket protocol — different message types, connection flows, and keep-alive behavior
Adding a second provider means writing and maintaining a second integration. Evaluating a new model means building a new integration before you can test a single request.

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What the SLNG Unified API changes

Without SLNG Unified APIWith SLNG Unified API
One SDK per providerOne HTTP/WebSocket endpoint for all
Different request schemasSame request body across providers
Provider-specific error handlingConsistent error responses
Weeks to evaluate a new modelChange the URL path, test immediately
Manual upgrades when better models shipNew models available as soon as SLNG adds them

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Always on the latest models

SLNG regularly adds new STT and TTS models. When one becomes available, it shows up as a new URL path. You don’t need to update SDKs or change how your requests work. Upgrading to a newer model is the same every time: swap the model in the URL and test it.

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When it matters most

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A/B testing models

Compare Deepgram Nova 3 against Whisper Large v3 in production by routing a percentage of traffic to each path. No code change — just URL routing.

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Failover

If a provider goes down, switch to another by changing the model path. Your request format, error handling, and response parsing all stay the same.

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Latency optimization

Deploy the same application across regions and route each region to the lowest-latency model. The Unified API supports both SLNG-hosted models (running on SLNG infrastructure) and third-party models (proxied to the provider’s API).

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Rapid prototyping

Try a new model by changing the URL. No SDK update, no request format change.

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What you still control

The Unified API doesn’t hide provider capabilities. You can pass voice identifiers, sample rates, encodings, language codes, and speed settings through the config object in the request body. For the full list of parameters and which providers support them, see Parameters coverage.