Bring your own keys - ThinnestAI

With bring your own keys (BYOK), your workspace uses your own accounts with the providers. The three jobs are speech-to-text, the LLM and the voice. You pay those providers directly, and we charge a flat platform fee.

	With your own keys
Chat reply	₹0.02 per reply
Call minute	₹1.00 a minute, all-in, our phone line included

BYOK is all three jobs or none: it turns on only when a speech-to-text key, an LLM key and a voice key are all added and checked. Any plan can turn it on. Each agent can also run its own model from your LLM key. On the agent’s Playground, the Model list shows every model your key reaches. Leave it on your key’s model, which is the one set in Settings → Your keys, or pick another for this agent alone. Each agent speaks with a voice you choose from your own voice provider. Open the agent’s Voice page: it lists every voice your key can use, and Play speaks a short line in the agent’s language. The preview runs on your account, so the provider charges you for those few characters. If a provider hosts its own sample of a voice, that sample plays instead, at no cost. An agent without a chosen voice speaks with a standard voice from your provider. On a call, all three run on your accounts: your speech-to-text hears the caller, your LLM answers, and your voice speaks. If one of your keys cannot be used when a call starts, the call is not answered on our providers instead.

In the console

Open Settings → Your keys. Each of the three cards has:

Provider. Choose who does that job.
Model. Every model the provider offers. Before you add a key, the list shows the models the provider offers. Once your key is checked, it shows the models your key reaches. Long lists are grouped by family, such as Flux, Aura-2 and Aura for Deepgram’s voices.
API key, plus any other field the provider needs. Azure, for example, needs a region.

Verify and save checks the key with the provider before storing it. A key the provider rejects is not saved. Keys are stored encrypted, and are only ever shown by their last four characters. Once all three cards are filled, switch on Use my own keys.

Providers

Job	Providers
Speech-to-text	Deepgram, AssemblyAI, Soniox, Speechmatics, Gladia, Sarvam, ElevenLabs, Cartesia, OpenAI, Groq, Mistral, Azure Speech
LLM	OpenAI, Anthropic Claude, Google Gemini, Groq, Mistral, Sarvam, DeepSeek, xAI Grok, Together AI, Fireworks AI, Cerebras, OpenRouter, or any OpenAI-compatible URL
Voice	Deepgram, ElevenLabs, Cartesia, OpenAI, Sarvam, Soniox, Mistral, Azure Speech, Rime, Inworld, Hume, Murf, Speechify

Azure Speech takes your key and region. If your Azure resource accepts its key only at its own address, as Azure AI Foundry resources do, also give its resource endpoint, such as https://my-resource.cognitiveservices.azure.com. Any OpenAI-compatible URL takes a base URL that starts with https://. Azure OpenAI’s https://<resource>.openai.azure.com/openai/v1 is one. If the server does not list its models, send the model id with the key, and we check the two together with a one-token request.

When a key fails

There is no fallback. If your provider refuses a request (a revoked key, no credit, rate limits), the reply fails. We do not answer on our own models and bill you for it. You get a notification naming the provider and the reason, at most once a day per provider.

Customers

If you build on our API with customers, your customers use your keys while BYOK is on. A customer can bring a complete set of three keys of its own, which then overrides yours. Turning BYOK off in your workspace turns it off for all your customers.

API

Every request below also works for a customer, with the Thinnest-Workspace header.

Status

GET /api/v1/byok

{
  "enabled": true,
  "using": "own",
  "complete": true,
  "credentials": [
    {
      "kind": "stt",
      "provider": "deepgram",
      "label": "Deepgram",
      "key": "…k9z2",
      "fields": { "model": "nova-3-general" },
      "model": "nova-3-general",
      "models": ["flux-general-en", "nova-3-general", "…"],
      "verifiedAt": "2026-10-06T10:00:00Z",
      "updatedAt": "2026-10-06T10:00:00Z"
    }
  ]
}

using is own, developer (a customer using its developer’s keys) or none. models is what the provider offered this key, and model is the one it runs.

Add or replace a key

PUT /api/v1/byok/credentials

{ "kind": "llm", "provider": "openai", "credentials": { "apiKey": "sk-…", "model": "gpt-5.4-mini" } }

kind. One of stt, llm or tts.
provider. One of the provider ids in the table above, in lower case. An error lists the ones that do that job.
credentials.model. Optional. Without it, a speech key starts on the provider’s usual model. An LLM key starts on the provider’s usual model when it has one; otherwise choose one.
Replacing a key. If you replace a key with one for the same provider, its model is kept.

Status	Why
`400`	The provider rejected the key, or does not offer that model on it.
`409`	BYOK is on, and this key would leave a job without a model.
`502`	The provider could not be reached to check the key. Try again.

Change the model, or refresh the list

PATCH /api/v1/byok/credentials/llm

{ "model": "gpt-5.4-nano" }

The key is not sent again. The model must be on the key’s models list. For a model the provider launched after you added the key, send "refreshModels": true, alone or together with the new model.

Turn BYOK on or off

PATCH /api/v1/byok

{ "enabled": true }

The request is refused with 409 until all three keys are added, checked, and each has a model.

Voices

GET /api/v1/byok/voices

{
  "provider": { "id": "elevenlabs", "label": "ElevenLabs" },
  "model": "eleven_flash_v2_5",
  "items": [
    { "id": "EXAVITQu4vr4xnSDxMaL", "name": "Sarah", "language": "en", "gender": "female", "sample": "https://…" }
  ]
}

These are the voices your voice provider offers your key. sample is a clip the provider hosts, when it has one. On Deepgram, a voice is a model, such as aura-2-helena-en or flux-alexis-en.

Preview a voice

POST /api/v1/byok/voices/preview

{ "voice": "EXAVITQu4vr4xnSDxMaL", "agentId": "agt_…" }

The response is the audio itself: audio/mpeg, or audio/wav for Sarvam. Without text, the voice speaks a short line of ours in the agent’s language, or in language if you send it. Any text you send is capped at 200 characters, because your provider charges you for every character. Soniox has no preview here: it speaks only on a live call.

Choose an agent’s model

GET /api/v1/models lists our models in items, as before. On a workspace using its own keys it also returns byok:

{ "byok": { "provider": { "id": "openai", "label": "OpenAI" }, "workspaceModel": "gpt-5.4-nano", "models": ["gpt-5.4-mini", "gpt-5.4-nano", "…"] } }

PUT /api/v1/agents/{id}/byok-model

{ "model": "gpt-5.4-mini" }

The model must be one your key reaches. Send null to go back to your key’s model. GET on the same path returns the agent’s choice. It also returns stale, the agent’s earlier choice, if your key no longer reaches it; until you choose again, the agent runs your key’s model.

Choose an agent’s voice

PUT /api/v1/agents/{id}/byok-voice

{ "voice": "EXAVITQu4vr4xnSDxMaL" }

The voice must be one that GET /byok/voices lists. Send null to go back to the provider’s standard voice. GET on the same path returns the agent’s current choice. To use a different voice for a single call, put it in that call’s overrides, as "overrides": { "voice": "EXAVITQu4vr4xnSDxMaL" } on POST /api/v1/calls or in a batch. On a workspace using its own keys, the voice must be one of yours from GET /byok/voices. A choice belongs to the provider it was made on. If you switch your voice key to another provider, the agent speaks with the new provider’s standard voice until you choose again. GET shows the old choice as stale until then.

Remove a key

DELETE /api/v1/byok/credentials/tts

The request is refused with 409 while BYOK is on. Replace the key instead, or turn BYOK off first. Changing keys or switching BYOK needs an API key with full access. A read-only key can see the status.

​In the console

​Providers

​When a key fails

​Customers

​API

​Status

​Add or replace a key

​Change the model, or refresh the list

​Turn BYOK on or off

​Voices

​Preview a voice

​Choose an agent’s model

​Choose an agent’s voice

​Remove a key