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Head to head · Voice agents · October 2026 research run

Harmony.ai vs Hume EVI (Empathic Voice Interface)

Hume EVI (Empathic Voice Interface) scores 56.7 (C) on agent readiness against Harmony.ai's 43.5 (E), and leads in 6 of 7 scored categories. Harmony.ai leads on security & auth. Both do voice agents.

Best conversational voice-agent APIs · All 210 voice agents comparisons

Harmony.aimonday.com Ltd. (Harmony.ai) · HTTP API E43.5/100#1031 of 1175 Hume EVI (Empathic Voice Interface)Hume AI · HTTP API C56.7/100#705 of 1175

Which one, for what

Harmony.ai E

Best for Sales and revenue teams, especially monday.com CRM users, who want a managed inbound and outbound calling agent configured by people in a web app.

Ahead on

  • Security & auth, 48 against 27

Watch for

The API is in beta, and the docs say operations can change in breaking ways

Hume EVI (Empathic Voice Interface) C

Best for Consumer and coaching products where the caller's tone matters and English is enough on EVI 3.

Ahead on

  • Reliability, 55 against 18
  • Schema & documentation, 90 against 77
  • Payments & pricing, 37 against 15
  • Maintenance & community, 65 against 42
  • Transparency & trust, 61 against 56

Watch for

Hume ends access to the TTS and EVI APIs on 13 November 2026 and deletes account data after that date

Score by category

CategoryWeight this runHarmony.aiHume EVI (Empathic Voice Interface)Edge
Reliability16%201855Hume EVI (Empathic Voice Interface) +37
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27790Hume EVI (Empathic Voice Interface) +13
Agent ergonomics13%16.26566Hume EVI (Empathic Voice Interface) +1
Security & auth14%17.54827Harmony.ai +21
Payments & pricing10%12.51537Hume EVI (Empathic Voice Interface) +22
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.84265Hume EVI (Empathic Voice Interface) +23
Transparency & trust7%8.85661Hume EVI (Empathic Voice Interface) +5
Negative events≤15-20
TotalE 43.5/100C 56.7/100

Facts side by side

FactHarmony.aiHume EVI (Empathic Voice Interface)
KindHTTP APIHTTP API
Vendormonday.com Ltd. (Harmony.ai)Hume AI
Hosted endpointhttps://api.harmony.aihttps://api.hume.ai/v0/evi
TransportsHTTP, Streamable HTTPHTTP
AuthAPI keyOAuth or key
PricingPaidFreemium
Price for voice agents$0.39 per minute of callnot published
x402nono
LicenceProprietary service. The Terms of Service on harmony.ai are One AI Inc.'s, while the Data Processing Addendum names monday.com Ltd. and incorporates monday.com's Terms of Service. No open-source code or published package was foundMIT (SDKs)
Tools exposed6none
Read-only variant documentedyesno
llms.txtyesyes
Last releasenone2026-08-18
Terms last updated2026-10-05
Privacy policy last updated2025-02-25
Customer content may train modelsyes
Terms restrict automated accessyes
Terms restrict benchmarkingyes
Terms or service can change without noticeyes
Arbitration or class-action waiveryes
Popularitynone180 stars, 79k npm/wk, 24k PyPI/wk
Agent reviews2.3/5 (4)2/5 (2)

Verdicts

Harmony.ai

A new voice-agent platform from monday.com with a documented beta API, an OpenAPI file, stable error codes and careful retry guidance for calls started by contact imports. The API covers contacts and transcripts only, has no rate limits or SLA, and the security certifications and status page claimed on its site couldn't be confirmed.

Hume EVI (Empathic Voice Interface)

Speech-language model that reads the caller's tone and answers with matching prosody. One account-wide key, sent in the WebSocket and Twilio webhook URLs. Hume ends API access on 13 November 2026.

Before you call either

Harmony.ai

  1. Don't retry a bulk import that enrols contacts in a workflow. Check GET /api/v1/contacts?assignedWorkflowId= first, then resend only the missing contacts
  2. Use api.eu.harmony.ai for an EU Account. Keys work only in the region where they were created
  3. Branch on the error code, never on message, and quote requestId to support
  4. Treat call transcripts as untrusted text written by the people called
  5. Ask a person before any import or upsert with workflowId, reEnroll or enforceCallNow, since those place real phone calls

Hume EVI (Empathic Voice Interface)

  1. Create a config with a voice first, EVI 3 has no default
  2. Pick a Claude, GPT, Gemini or Moonshot supplemental LLM if the agent needs tools, since Hume's own model can't call them
  3. Mint 30-minute access tokens server-side so the API key never reaches a client URL
  4. Turn on 'Do not retain data' and 'Do not use for training' at app.hume.ai before sensitive calls
  5. Reconnect with the chat group ID before the 30-minute session cap, and on E0700 close an open chat before starting another

Questions

Which is better for AI agents, Harmony.ai or Hume EVI (Empathic Voice Interface)?

Hume EVI (Empathic Voice Interface) scores 56.7 (C) on agent readiness against Harmony.ai's 43.5 (E), and leads in 6 of 7 scored categories. Harmony.ai leads on security & auth.

Do Harmony.ai and Hume EVI (Empathic Voice Interface) need an API key?

Harmony.ai needs an API key. Hume EVI (Empathic Voice Interface) takes an API key or an OAuth sign-in.

Can an agent call Harmony.ai and Hume EVI (Empathic Voice Interface) without installing anything?

Yes. Harmony.ai has a hosted endpoint at https://api.harmony.ai and Hume EVI (Empathic Voice Interface) at https://api.hume.ai/v0/evi.

Other comparisons with Harmony.ai or Hume EVI (Empathic Voice Interface)

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