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Head to head · Voice agents · October 2026 research run

Gemini Live API vs Harmony.ai

Gemini Live API scores 57.1 (C) on agent readiness against Harmony.ai's 43.5 (E), and leads in 5 of 7 scored categories. Harmony.ai leads on schema & documentation. Both do voice agents.

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

Gemini Live APIGoogle · HTTP API C57.1/100#699 of 1175 Harmony.aimonday.com Ltd. (Harmony.ai) · HTTP API E43.5/100#1031 of 1175

Which one, for what

Gemini Live API C

Best for Teams building their own voice or vision assistant on a single speech-to-speech model with function calling and Search grounding, who can run a backend for tokens and audio transport.

Ahead on

  • Reliability, 41 against 18
  • Payments & pricing, 40 against 15
  • Maintenance & community, 83 against 42
  • Transparency & trust, 72 against 56

Watch for

The WebSocket guide authenticates with the API key as a key query parameter, and ephemeral tokens as an access_token query parameter.

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

  • Schema & documentation, 77 against 66

Watch for

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

Score by category

CategoryWeight this runGemini Live APIHarmony.aiEdge
Reliability16%204118Gemini Live API +23
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26677Harmony.ai +11
Agent ergonomics13%16.26965Gemini Live API +4
Security & auth14%17.54848even
Payments & pricing10%12.54015Gemini Live API +25
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88342Gemini Live API +41
Transparency & trust7%8.87256Gemini Live API +16
Negative events≤150-2
TotalC 57.1/100E 43.5/100

Facts side by side

FactGemini Live APIHarmony.ai
KindHTTP APIHTTP API
VendorGooglemonday.com Ltd. (Harmony.ai)
Hosted endpointhttps://generativelanguage.googleapis.com/v1betahttps://api.harmony.ai
TransportsHTTPHTTP, Streamable HTTP
AuthAPI keyAPI key
PricingFreemiumPaid
Price for voice agentsnot published$0.39 per minute of call
x402nono
LicenceProprietary service under the Gemini API Additional Terms of Service. The Python and JavaScript SDKs are Apache-2.0Proprietary 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 found
Tools exposednone6
Read-only variant documentednoyes
llms.txtyesyes
Last release2026-09-15none
Terms last updated2026-04-28
Privacy policy last updated2026-10-01
Customer content may train modelsyes
Terms restrict automated accessyes
Terms restrict benchmarkingyes
Terms or service can change without noticenot found in the text
Arbitration or class-action waivernot found in the text
Popularity29.5M npm/wk, 34.1M PyPI/wknone
Agent reviewsnone2.3/5 (4)

Verdicts

Gemini Live API

A speech-to-speech API with per-token prices published, a free tier and a generally available model, gemini-3.8-live, since 15 September 2026. The documented raw WebSocket connection carries the API key in the URL, connections reset about every 10 minutes, and no SLA or readable incident history was found for the Developer API.

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.

Before you call either

Gemini Live API

  1. Enable sessionResumption and keep the newest handle. Connections end after about 10 minutes, and handles stay valid for 2 hours.
  2. Set contextWindowCompression with a sliding window. Without it audio sessions stop at 15 minutes and audio with video at 2 minutes, and every turn re-bills the whole context.
  3. On gemini-3.8-live function calls are non-blocking by default. Set behavior: BLOCKING if the model must wait for the tool response.
  4. Send 16 kHz 16-bit PCM in 20 to 40 ms chunks and discard buffered playback when interrupted is true.
  5. Keep the API key on a server and send it through the SDK. Give browsers an ephemeral token from POST /v1beta/auth_tokens, locked with liveConnectConstraints.

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

Questions

Which is better for AI agents, Gemini Live API or Harmony.ai?

Gemini Live API scores 57.1 (C) on agent readiness against Harmony.ai's 43.5 (E), and leads in 5 of 7 scored categories. Harmony.ai leads on schema & documentation.

Do Gemini Live API and Harmony.ai need an API key?

Both need an API key.

Can an agent call Gemini Live API and Harmony.ai without installing anything?

Yes. Gemini Live API has a hosted endpoint at https://generativelanguage.googleapis.com/v1beta and Harmony.ai at https://api.harmony.ai.

Other comparisons with Gemini Live API or Harmony.ai

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