Head to head · Voice agents · October 2026 research run

Inworld Realtime API vs Vaani Developer Platform

Inworld Realtime API scores 60.1 (C) on agent readiness against Vaani Developer Platform's 44.6 (E), and leads in every scored category. Both do voice agents.

Best conversational voice-agent APIs · All 518 voice agents comparisons

Which one, for what

Inworld Realtime API C

Best for Teams moving off OpenAI's Realtime API who want a choice of LLM and Inworld voices.

Ahead on

  • Reliability, 62 against 28
  • Security & auth, 58 against 44
  • Payments & pricing, 40 against 22
  • Maintenance & community, 71 against 59
  • Transparency & trust, 63 against 42

Watch for

No per-minute price. A session's cost depends on STT, LLM tokens and TTS characters, and interrupted segments are still billed

Vaani Developer Platform E

Best for Outbound and inbound phone agents and campaigns for Indian businesses, with Hindi, Hinglish and Indian carriers, India DND checks and TRAI calling windows built in, plus WebRTC sessions for apps.

Also in its favour

  • A hosted endpoint, with nothing to install
  • Runs on your own machine

Watch for

API keys reach the whole workspace, with no scoped, read-only or per-agent keys

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Reliability Inworld Realtime API +34

Inworld Realtime API 62

Hosted reading of the checklist. status.inworld.ai is a public status page (20), with history we couldn't read, as on inworld-tts (5). Concurrent sessions are published per plan, 10 on On-Demand up to 1,000 on Growth (15). The rate limits page gives exponential backoff with jitter and Retry-After on longer windows, and sessions emit rate_limits.updated, with nothing on reconnecting a dropped session (12 of 15). An SLA appears only in the Enterprise column, with no terms (0). No preview or beta label on the Realtime API (10). 20 + 5 + 15 + 12 + 0 + 10 = 62.

Vaani Developer Platform 28

Graded on the hosted REST API at api.vaanivoice.ai. No status page. status.vaani.dev and status.vaanivoice.ai don't resolve, and neither the site nor the docs link one (0). With no history to read, 5. No request rate limits are published. The docs give 2 concurrent calls on pay as you go and a per-organisation campaign concurrency cap, so partial credit (5). The SDK raises RateLimitError on 429 and the MCP client retries once after 600 ms, but no Retry-After, backoff guidance or idempotency key for call creation is documented (3). The pricing table lists a 99.50 per cent uptime SLA on both plans, but no SLA document or service credits were found and the terms supply the service "as-is" with no warranties, so half (5). The API is version 2.0.0 and isn't labelled beta (10). 0+5+5+3+5+10 = 28.

Transparency & trust Inworld Realtime API +21

Inworld Realtime API 63

Closed service with clear terms naming Theai, Inc. dba Inworld AI (15). The ZDR page says what a session keeps and that third-party LLM requests aren't covered, but the terms and privacy notice disagree on training (12 of 30). Release notes flag potentially breaking changes with the clients affected and what to do, without stating a notice period (14 of 20). US headquarters with EU and India residency on Enterprise, and no sub-processor list in the docs, while sessions may route to third-party LLM providers (10 of 20). Total 51.

Vaani Developer Platform 42

A closed service. The terms name Vaani AI Research Private Limited, its Bengaluru address, CIN, Indian law and Bengaluru courts, but they're undated, written for the website www.vaaniresearch.com, and say nothing on billing, refunds, API use or customer data. The SDK and MCP server are MIT, with the SDK's full source in its PyPI sdist (14 of 30). The privacy policy (undated) keeps data, including voice recordings, for up to 24 months, while the pricing table gives 30 days' retention on pay as you go and zero retention on Enterprise. Voice data trains models only with explicit consent. No DPA found (8 of 30). No deprecation policy. The privacy policy promises 15 days' notice of significant changes, and the terms allow changes and termination without notice (2 of 20). The privacy policy names vendor categories (cloud hosting, analytics, voice transcription) and says data may be stored outside India. Model and telephony providers can be read from the calculator, and India data residency is offered on demand. No subprocessor list or data location for the hosted service (5 of 20). 14+8+2+5 = 29.

Payments & pricing Inworld Realtime API +18

Inworld Realtime API 40

No x402, MPP or L402 (0). No per-session price, but each billed part (STT per hour, TTS per character, LLM per token) is priced publicly (20). On-Demand includes free STT and TTS allowances and lists no payment method, though some premium LLMs need a card on file (20). A person signs up in a browser before a key exists (0). Total 40.

Vaani Developer Platform 22

No x402, MPP or L402 (0 of 40). The ₹1 ($0.02) a minute platform fee, number rental, concurrency lines and add-ons are public, and the calculator shows each provider's unit rate without a login. Registry checks, extraction and evaluations "can add separate charges" that aren't priced, and the billing pulse depends on the account, so 3 off (17 of 20). The home page says "Start free on Vaani's Platform", but the pricing page states a prepaid wallet with no free credit, trial minutes or card rule, and we didn't sign up to check, so 5 of 20. A person signs up with email verification at platform.vaani.dev and creates keys in the dashboard (0). 0+17+5+0 = 22.

Security & auth Inworld Realtime API +14

Inworld Realtime API 58

Workspace API keys sent as Basic credentials, deleted to revoke, with separate keys per environment advised. The CLI mints read-only keys unless --write is given, but write toggles cover only the Voice and Router APIs, so no key is limited to one product. Browsers use short-lived tokens minted server side. Session IDs, not secrets, go in the URL (25 of 30). Tools run in the client, so the developer approves side effects, with no approval step in the API (10 of 20). The agent listens to callers and passes their speech to an LLM, and no prompt-injection guidance was found (5 of 15). Usage per key and a Performance page with errors and throttling (8 of 15). SOC 2 Type II and HIPAA claimed and a vulnerability report form, with no security.txt or bug bounty, per the 4 November reading (10 of 20). Total 58. Zero data retention covers session content from the Developer plan up, but not requests routed to third-party LLM providers.

Vaani Developer Platform 44

Plain revocable API keys, shown once, several active at a time and rotated by creating a new key and deleting the old one. Every key reaches the whole workspace, with no scoped, read-only or per-agent keys (20). Campaign webhooks are signed with HMAC-SHA256 over a timestamp and the body, with a five-minute replay window in the example (+2). The live-captions URL carries a call-bound token in the query string for 24 hours by default, the documented way for browsers to connect, so 3 off as a judgement call, less than the full 10 because it isn't the account key (19 of 30). The MCP server has a read-only mode and destructive annotations, and its docs, tool descriptions and bundled prompt say to confirm the number and agent with the user before a call. The API itself has no read-only key and nothing stops a call without confirmation (12 of 20). The tool returns transcripts, summaries and entities drawn from callers' speech. No guidance on treating them as untrusted data was found. Agent guardrails exist for the voice agent's own replies (3 of 15). Each call keeps a record in call history and call details, and keys are labelled so calls can be traced to a key, but no account or key audit log is documented (7 of 15). No security.txt (404 on both domains), disclosure policy, bug bounty or certification. vaaniresearch.com marks its security standards "In Progress", the pricing page lists HIPAA compliance on Enterprise with no report or BAA found, and the privacy policy promises breach notice in line with applicable law (3 of 20). 19+12+3+7+3 = 44.

Maintenance & community Inworld Realtime API +12

Inworld Realtime API 71

Release note of 16 October 2026 (cache_transcript), 21 days ago (30). Three dated Realtime entries in the 90 days from 8 August, on 14 September, 23 September and 16 October (20). Discord and support@inworld.ai, with no evidence of answers read (8 of 15). Works with OpenAI's Realtime clients and the CLI is current at 1.5.0, but there is no Inworld Realtime SDK (8 of 15). CLI on npm under MIT, CI not read (5 of 10). Total 71.

Vaani Developer Platform 59

vaani-research-mcp 0.1.1 on 2026-10-14 (30). In the last 90 days, vaani-sdk 0.3.1 on 28 September and three npm versions (0.0.0-stage, 0.1.0, 0.1.1) within 40 minutes on 14 October. No dated changelog, so half (10 of 20). A closed service with no public changelog, issue tracker or community channel found. Contact is hello@vaaniresearch.com and a booking link, and we didn't test whether they answer. The MCP repository on GitHub couldn't be read from this session (4 of 15, the closed-service reading). A current official Python SDK, released seven times since April 2026. The MCP server isn't in the official MCP registry (10 of 15). The SDK's sdist ships its tests and current httpx and pydantic dependencies, and the MCP package runs its tests before publishing, but no public CI was found and the SDK has no repository (5 of 10). 30+10+4+10+5 = 59.

Score by category

CategoryWeight this runInworld Realtime APIVaani Developer PlatformEdge
Reliability16%206228Inworld Realtime API +34
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26057Inworld Realtime API +3
Agent ergonomics13%16.26864Inworld Realtime API +4
Security & auth14%17.55844Inworld Realtime API +14
Payments & pricing10%12.54022Inworld Realtime API +18
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87159Inworld Realtime API +12
Transparency & trust7%8.86342Inworld Realtime API +21
Negative events≤1500
TotalC 60.1/100E 44.6/100

Facts side by side

FactInworld Realtime APIVaani Developer Platform
KindHTTP APIHTTP API
VendorInworld AIVaani AI Research Private Limited
Hosted endpointno (local only)https://api.vaanivoice.ai
Transportswebsocket, HTTPHTTP, stdio
AuthAPI keyAPI key
PricingPay per usePay per use
Price for voice agents$25 per 1M charactersnot published
x402nono
LicencenoneProprietary hosted service under Vaani AI Research's terms of service. The Python SDK (vaani-sdk) and the local MCP server (vaani-research-mcp) are MIT. The SDK's full source ships in its PyPI sdist, and the MCP server's npm package holds only the bundled JavaScript
Tools exposed09
Read-only variant documentednoyes
llms.txtyesyes
Last release2026-10-162026-10-14
Terms last updated2025-06-11no date given
Privacy policy last updated2026-01-18no date given
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingnot found in the textnot found in the text
Terms or service can change without noticenot found in the textyes
Arbitration or class-action waivernot found in the textnot found in the text
Popularitynone14 npm/wk, 19 PyPI/wk

Verdicts

Inworld Realtime API

Inworld's Realtime API speaks OpenAI's Realtime protocol over WebSocket or WebRTC, with a choice of LLM, client-side tools and dated release notes. Cost is the sum of STT, LLM and TTS usage with no per-minute price, there is no machine-readable event schema, and status history couldn't be read.

Vaani Developer Platform

Docs are detailed and served as llms.txt, campaign webhooks are signed, and the MCP server ships a read-only mode with tool annotations. Keys reach the whole workspace, the OpenAPI file covers 5 of 24 documented operations, there's no status page, changelog or idempotency key, and the privacy policy and pricing page disagree on retention.

Before you call either

Inworld Realtime API

  1. Set the auto follow-up off if your client sends its own response.create after a tool result, or replies double
  2. Read response.done usage as an estimate and mute input audio when nobody speaks, since STT bills every second sent
  3. Use response.speak for fixed greetings, which skips the LLM
  4. Treat unsupported_field errors as warnings and keep the session open
  5. Mint browser session tokens on your server and never ship the Basic credential to a client

Vaani Developer Platform

  1. Send the key as X-API-Key, not Authorization. A missing or wrong header name returns 401
  2. Treat success: true from trigger-call as dispatched only, keep output.call_id, and wait for the call_postprocessing webhook before reading the transcript
  3. Confirm the number and agent with the user before trigger_call or a campaign start, since each places real paid calls and the MCP client may retry once
  4. Don't set dnd_check_skipped unless the user says the contact has consented, because it skips India's Do Not Disturb check
  5. Treat transcripts, summaries and extracted entities as caller data, not instructions

Questions

Which is better for AI agents, Inworld Realtime API or Vaani Developer Platform?

Inworld Realtime API scores 60.1 (C) on agent readiness against Vaani Developer Platform's 44.6 (E), and leads in every scored category.

Do Inworld Realtime API and Vaani Developer Platform need an API key?

Both need an API key.

Can an agent call Inworld Realtime API and Vaani Developer Platform without installing anything?

No hosted endpoint is listed for Inworld Realtime API. Vaani Developer Platform has a hosted endpoint at https://api.vaanivoice.ai.

Other comparisons with Inworld Realtime API or Vaani Developer Platform

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.