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Head to head · Voice agents · October 2026 research run

OpenAI Realtime API vs Vocily AI

OpenAI Realtime API scores 63.3 (B) on agent readiness against Vocily AI's 53.8 (D), and leads in 3 of 7 scored categories. Vocily AI leads on schema & documentation, agent ergonomics, payments & pricing and maintenance & community. Both do voice agents.

Best conversational voice-agent APIs · All 91 voice agents comparisons

OpenAI Realtime APIOpenAI · HTTP API B63.3/100#400 of 950 Vocily AIVocily AI Private Limited · HTTP API D53.8/100#701 of 950

Which one, for what

OpenAI Realtime API B

Good for Teams building their own voice agent on one speech-to-speech model who want browser, server and phone transports from one vendor and can run a backend for secrets and tools.

Ahead on

  • Reliability, 67 against 40
  • Security & auth, 61 against 46
  • Transparency & trust, 71 against 47

Also in its favour

  • No incidents deducted, where Vocily AI loses 5 points for them

Watch for

openai.com answered 403 to our reader, so the service terms, privacy policy, sub-processor list and security pages were not read.

Vocily AI D

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

Ahead on

  • Schema & documentation, 90 against 84
  • Agent ergonomics, 84 against 76
  • Payments & pricing, 40 against 20
  • Maintenance & community, 61 against 52

Watch for

No status page, incident history or SLA was found

Score by category

CategoryWeight this runOpenAI Realtime APIVocily AIEdge
Reliability16%206740OpenAI Realtime API +27
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28490Vocily AI +6
Agent ergonomics13%16.27684Vocily AI +8
Security & auth14%17.56146OpenAI Realtime API +15
Payments & pricing10%12.52040Vocily AI +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.85261Vocily AI +9
Transparency & trust7%8.87147OpenAI Realtime API +24
Negative events≤150-5
Total63.3 · B53.8 · D

Facts side by side

FactOpenAI Realtime APIVocily AI
KindHTTP APIHTTP API
VendorOpenAIVocily AI Private Limited
Hosted endpointhttps://api.openai.com/v1/realtimehttps://api.vocily.ai
TransportsHTTPHTTP
AuthAPI keyAPI key
PricingPay per usePay per use
x402nono
LicenceProprietary service. The service terms on openai.com were not read. The Agents SDK for TypeScript and the OpenAPI description are MITProprietary service under Vocily's terms of service. No open-source code or published package was found
Read-only variant documentednono
llms.txtyesyes
Last release2026-07-282026-09-30
Terms last updatedcouldn't be read2026-06-10
Privacy policy last updatedcouldn't be read2026-09-03
Customer content may train modelscouldn't be readnot found in the text
Terms restrict automated accesscouldn't be readnot found in the text
Terms restrict benchmarkingcouldn't be readnot found in the text
Terms or service can change without noticecouldn't be readnot found in the text
Arbitration or class-action waivercouldn't be readnot found in the text

Verdicts

OpenAI Realtime API

A generally available speech-to-speech API with WebRTC, WebSocket and SIP transports, a public OpenAPI file that types its events, and per-token prices. Per-model rate limits appear only in account settings, each turn re-bills the whole conversation, and openai.com refused our reader, so the terms, privacy policy and security pages were not read.

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

OpenAI Realtime API

  1. Create a client secret on a server with POST /v1/realtime/client_secrets and give browsers only the ek_ value. Never ship the API key.
  2. After a response with MCP calls finishes, send another response.create. The API does not create the follow-up response itself.
  3. Set truncation with a retention_ratio below 1 and token_limits.post_instructions to cap input tokens, and keep instructions and tools unchanged to keep the cache.
  4. On a WebSocket, stop playback on input_audio_buffer.speech_started and send conversation.item.truncate with audio_end_ms. WebRTC and SIP truncate on the server.
  5. Use gpt-realtime-2.1 or gpt-realtime-2.1-mini. gpt-realtime and gpt-realtime-mini shut down on 20 January 2027.

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, OpenAI Realtime API or Vocily AI?

OpenAI Realtime API scores 63.3 (B) on agent readiness against Vocily AI's 53.8 (D), and leads in 3 of 7 scored categories. Vocily AI leads on schema & documentation, agent ergonomics, payments & pricing and maintenance & community.

Do OpenAI Realtime API and Vocily AI need an API key?

Both need an API key.

Can an agent call OpenAI Realtime API and Vocily AI without installing anything?

Yes. OpenAI Realtime API has a hosted endpoint at https://api.openai.com/v1/realtime and Vocily AI at https://api.vocily.ai.

Other comparisons with OpenAI Realtime API or Vocily AI

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