Rate limits | Nari Labs | Documentation

Each organization has separate Text to Speech (TTS) and Speech to Text (STT) concurrency limits. Standard and Fast models share the limit within each API across API keys and Playground activity.

Limits apply per organization in each API region:

Billing tier	TTS requests	STT connections
Paid Tier 1	20	20
Enterprise	Custom	Custom

For TTS, a concurrent session is an in-flight speech request. For STT, it is an open realtime WebSocket connection, which can transcribe multiple utterances.

A single credit purchase of $100 or more upgrades an organization to Paid Tier 1. Smaller purchases do not accumulate toward the upgrade. For higher concurrency, contact founders@narilabs.com.

Limit errors

When a request exceeds a limit, use error.code to choose the appropriate retry behavior:

Code	Action
`CONCURRENCY_LIMIT_EXCEEDED`	Wait for a TTS request or STT session to finish, then retry.
`UPSTREAM_RATE_LIMITED`	Retry with exponential backoff and a small random delay.

The error guide covers the complete error response and retryable server failures.

For STT duration, idle timeout, and message size limits, see Session limits.