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Head to head · Voice agents · October 2026 research run

Harmony.ai vs Vocily AI

Vocily AI scores 53.8 (D) on agent readiness against Harmony.ai's 43.5 (E), and leads in 5 of 7 scored categories. Harmony.ai leads on transparency & trust. 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 Vocily AIVocily AI Private Limited · HTTP API D53.8/100#794 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

  • Transparency & trust, 56 against 47

Watch for

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

Vocily AI D

Best for Indian-language phone agents where a backend builds agents, places outbound calls and reads results over REST, with prepaid rupee billing.

Ahead on

  • Reliability, 40 against 18
  • Schema & documentation, 90 against 77
  • Agent ergonomics, 84 against 65
  • Payments & pricing, 40 against 15
  • Maintenance & community, 61 against 42

Watch for

No status page, incident history or SLA was found

Score by category

CategoryWeight this runHarmony.aiVocily AIEdge
Reliability16%201840Vocily AI +22
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27790Vocily AI +13
Agent ergonomics13%16.26584Vocily AI +19
Security & auth14%17.54846Harmony.ai +2
Payments & pricing10%12.51540Vocily AI +25
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.84261Vocily AI +19
Transparency & trust7%8.85647Harmony.ai +9
Negative events≤15-2-5
TotalE 43.5/100D 53.8/100

Facts side by side

FactHarmony.aiVocily AI
KindHTTP APIHTTP API
Vendormonday.com Ltd. (Harmony.ai)Vocily AI Private Limited
Hosted endpointhttps://api.harmony.aihttps://api.vocily.ai
TransportsHTTP, Streamable HTTPHTTP
AuthAPI keyAPI key
PricingPaidPay per use
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 foundProprietary service under Vocily's terms of service. No open-source code or published package was found
Tools exposed6none
Read-only variant documentedyesno
llms.txtyesyes
Last releasenone2026-09-30
Terms last updated2026-06-10
Privacy policy last updated2026-09-03
Customer content may train modelsnot found in the text
Terms restrict automated accessnot found in the text
Terms restrict benchmarkingnot found in the text
Terms or service can change without noticenot found in the text
Arbitration or class-action waivernot found in the text
Agent reviews2.3/5 (4)none

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.

Vocily AI

The REST API is documented in detail for a product a few months old, with an OpenAPI 3.1 file, required idempotency keys on calls, a Retry-After header on 429 and signed webhooks. No status page, SLA, SDK or security programme was found, and two releases in September 2026 removed fields under /v1 on the day they were announced.

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

Vocily AI

  1. Send a fresh UUID in Idempotency-Key on every POST /v1/calls. The API refuses the request without it
  2. Pass a from_number the workspace holds. The shared Test Number returns 403 from the API
  3. Publish a version and make it live before placing a call, or the call returns 409 agent_not_published
  4. Branch on detail.code, falling back to the top-level code. A 429 body is flat, so read Retry-After
  5. Read currency on every call and chat record. Costs are in rupees or dollars depending on the organisation

Questions

Which is better for AI agents, Harmony.ai or Vocily AI?

Vocily AI scores 53.8 (D) on agent readiness against Harmony.ai's 43.5 (E), and leads in 5 of 7 scored categories. Harmony.ai leads on transparency & trust.

Do Harmony.ai and Vocily AI need an API key?

Both need an API key.

Can an agent call Harmony.ai and Vocily AI without installing anything?

Yes. Harmony.ai has a hosted endpoint at https://api.harmony.ai and Vocily AI at https://api.vocily.ai.

Other comparisons with Harmony.ai or Vocily AI

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