Hume EVI (Empathic Voice Interface)

Overview

Best for: Nothing new. Existing integrations should migrate before 2026-11-13.

At a glance

Shutting down November 13, 2026. 11 languages on EVI 4-mini (EVI 3 English only). Price is third-party reported Starter overage ($0.04 to $0.07 by plan). Free plan 5 min/month (third-party). Supplemental LLM optional on EVI 3, required on EVI 4-mini.

Features

• expression (prosody) measures per sentence
• tone-aware end-of-turn detection
• interruption handling
• supplemental LLMs (Anthropic, OpenAI, Google, Fireworks and others)
• configs and chat history resume

Pricing

Free tier: 5 EVI minutes per month (third-party data).

Source: fish.audio

Setup

1. Do not start new projects: the API shuts down on 2026-11-13.
2. Existing users: export any chat data you need before the deadline and plan a migration (Hume points to Real World VoiceEQ for comparing alternatives).
3. Connect to the EVI chat WebSocket with api_key (server) or access_token (browser) and a config_id.

Endpoint

wss://api.hume.ai/v0/evi/chat

Authentication

api_key or access_token query parameter (REST uses X-HUME-API-KEY header)

// EVI is being shut down on 2026-11-13. Only for existing integrations.
// npm i ws. Use an access token (not the API key) from browsers.
import WebSocket from "ws";

const url = `wss://api.hume.ai/v0/evi/chat?api_key=${process.env.HUME_API_KEY}&config_id=${process.env.HUME_CONFIG_ID}`;
const ws = new WebSocket(url);

ws.on("open", () => {
  // Raw PCM must be declared; WebM from browsers needs no settings.
  ws.send(JSON.stringify({
    type: "session_settings",
    audio: { encoding: "linear16", sample_rate: 44100, channels: 1 },
  }));
});

export function sendPcm(buf) {
  ws.send(JSON.stringify({ type: "audio_input", data: buf.toString("base64") }));
}

ws.on("message", (raw) => {
  const ev = JSON.parse(raw.toString());
  if (ev.type === "audio_output") playWav(Buffer.from(ev.data, "base64")); // base64 WAV
  if (ev.type === "user_message") console.log(ev.message?.content, ev.models?.prosody);
});
function playWav(wav) {}

Written from the current docs. Check the vendor's SDK version before you ship.

Warnings

Plus 14 warnings that apply to all voice-to-voice APIs. See category warnings.

Limits

• Access ends November 13, 2026 at 12:01 a.m. EST; account data permanently deleted after that
• Max session duration 30 minutes
• Max WebSocket message 16 MB
• HTTP rate limit 100 requests per second
• Concurrent sessions set by subscription tier

Models and products

Docs and sources

Docs

• EVI overview (sunset notice)
• Changelog
• EVI chat WebSocket reference

Sources used

• dev.hume.ai/docs/speech-to-speech-evi/overview
• dev.hume.ai/docs/introduction
• dev.hume.ai/changelog
• dev.hume.ai/docs/speech-to-speech-evi/guides/audio
• fish.audio/vs/pricing/hume-ai/
• usagepricing.com/blueprint/hume-ai