Head to head · Voice agents · October 2026 research run

Amazon Nova 2 Sonic vs Inworld Realtime API

Amazon Nova 2 Sonic scores 67.6 (B) on agent readiness against Inworld Realtime API's 60.1 (C), and leads in 4 of 7 scored categories. Inworld Realtime API leads on payments & pricing and maintenance & community. Both do voice agents.

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

Which one, for what

Amazon Nova 2 Sonic B

Best for Voice agents on AWS, call centres on Amazon Connect, teams that want IAM and in-account data handling.

Ahead on

  • Reliability, 95 against 62
  • Schema & documentation, 75 against 60
  • Security & auth, 77 against 58
  • Transparency & trust, 79 against 63

Watch for

Connections end after 8 minutes, so long calls need the session-continuation pattern

Inworld Realtime API C

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

Ahead on

  • Payments & pricing, 40 against 10
  • Maintenance & community, 71 against 50

Watch for

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

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 Amazon Nova 2 Sonic +33

Amazon Nova 2 Sonic 95

Hosted reading. AWS Health Dashboard with per-service, per-Region history (20). The dashboard history file (newest event 30 October 2026) lists no Bedrock event in the 90 days from 8 August, and the 3 September us-west-2 event names STS, Connect and IAM Identity Center, not Bedrock. The public dashboard records broad events only, so 25 of 30, as amazon-nova-embeddings was read. Quotas published, 20 concurrent requests per Region, not adjustable (15). The stream API lists ThrottlingException (429), ServiceUnavailableException (503), ModelTimeoutException (408) and ModelStreamErrorException (424), Bedrock's troubleshooting guide advises backoff with jitter, and the 8-minute connection limit comes with a session-continuation sample (15). Bedrock's SLA of 99.9 per cent a month per Region for model APIs, as read for amazon-nova-embeddings on 1 November (10). Generally available since 2 December 2025 (10). 20 + 25 + 15 + 15 + 10 + 10 = 95.

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.

Payments & pricing Inworld Realtime API +30

Amazon Nova 2 Sonic 10

No x402, MPP or L402 (0). The Nova and Bedrock pricing pages carry a speech-to-speech table drawn by script, so the per-token prices weren't read and this line scores absent, which is our reader's limit and not the vendor's (0). New accounts get up to $200 in Free Tier credits, and the Free Tier FAQ says most new customers need no payment method, read as half on the other AWS listings (10). A person signs up for an AWS account in a browser (0). Total 10.

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.

Maintenance & community Inworld Realtime API +21

Amazon Nova 2 Sonic 50

Read as a model. The newest dated change is the May 2026 refresh, completed on 28 May, 162 days before this check (10). No Sonic release note or document history entry in the 90 days from 8 August. The pre-alpha Python SDK shipped 0.9.0, 0.10.0, 0.11.0 and 0.12.0 in the window, counted half (10 of 20). Release notes, document history, re:Post and AWS Support (10 of 15). The JavaScript Bedrock runtime client is current at 3.1163.0, while the Python route is pre-alpha (10 of 15). The SDKs ship on AWS's release train; CI not read (10). Total 50.

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.

Security & auth Amazon Nova 2 Sonic +19

Amazon Nova 2 Sonic 77

SigV4 with IAM roles and temporary credentials scoped per model ARN, as the Sonic quickstart signs (30). Tools run in the client, so side effects are the developer's to approve, and IAM can restrict which models a role invokes, with no approval step in the API (12 of 20). The model listens to callers and acts on tool results, and no prompt-injection guidance was found in the Sonic guide (5 of 15). CloudTrail logs Bedrock API calls, read as amazon-nova-embeddings was (12 of 15). VDP on HackerOne, Bedrock in SOC scope and a valid security.txt on aws.amazon.com, with no paid bounty, as on the other AWS listings (18 of 20). Total 77.

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.

Transparency & trust Amazon Nova 2 Sonic +16

Amazon Nova 2 Sonic 79

Closed model under the AWS Service Terms, with Apache-2.0 SDKs and samples (15). Bedrock stores no inputs or outputs by default and model providers can't see them, Sonic isn't on the abuse-detection page's list of models whose traffic is stored, and section 50.3 doesn't list Bedrock among services whose content improves AWS services, as read for amazon-nova-embeddings on 1 November (22 of 30). Bedrock's lifecycle policy for models launched before 7 September 2026 promises 12 months and a Legacy period of at least 6 months, but the March and May refreshes changed the model in place under the same ID (15 of 20). Regions are listed, with sub-processors not read (12 of 20). Total 64.

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.

Schema & documentation Amazon Nova 2 Sonic +15

Amazon Nova 2 Sonic 75

The Bedrock service model types InvokeModelWithBidirectionalStream, but the Sonic events inside it (session, prompt, content, tool and usage events) are JSON payloads documented only in the guide, with no schema file (12 of 25). llms.txt and Markdown copies of the Nova 2 guide (10). Guides on the event lifecycle, barge-in, turn-taking, async tools and chat history say when and how to use each (16 of 20). Event fields are documented as JSON examples and tables, not typed schemas (10 of 15). Sample repositories in several languages and the API's exceptions with HTTP codes (12 of 15). Release notes and document history, with in-place model refreshes and a versioned model ID (15). Total 75.

Inworld Realtime API 60

No AsyncAPI or other machine-readable file for the socket, and the spec paths redirect (0). llms.txt, Markdown twins and a docs MCP server (10). The overview, OpenAI migration guide, providerData reference and the billing page's account of how a session is counted say what to use when (16 of 20). The reference lists every client and server event with field types and required marks, as text rather than a schema (12 of 15). JavaScript and Python example projects and an error event with type, code and param, without a list of codes (9 of 15). Dated release notes with affected clients and required actions, but no API version beyond /v1 (13 of 15). Total 60.

Score by category

CategoryWeight this runAmazon Nova 2 SonicInworld Realtime APIEdge
Reliability16%209562Amazon Nova 2 Sonic +33
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27560Amazon Nova 2 Sonic +15
Agent ergonomics13%16.26468Inworld Realtime API +4
Security & auth14%17.57758Amazon Nova 2 Sonic +19
Payments & pricing10%12.51040Inworld Realtime API +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.85071Inworld Realtime API +21
Transparency & trust7%8.87963Amazon Nova 2 Sonic +16
Negative events≤1500
TotalB 67.6/100C 60.1/100

Facts side by side

FactAmazon Nova 2 SonicInworld Realtime API
KindHTTP APIHTTP API
VendorAmazon Web ServicesInworld AI
Hosted endpointno (local only)no (local only)
TransportsHTTPwebsocket, HTTP
AuthAPI keyAPI key
PricingPay per usePay per use
Price for voice agentsnot published$25 per 1M characters
x402nono
Tools exposed00
Read-only variant documentednono
llms.txtyesyes
Last release2026-05-282026-10-16
Terms last updated2026-10-012025-06-11
Privacy policy last updated2026-05-182026-01-18
Customer content may train modelsyes, with an opt-outnot found in the text
Terms restrict automated accessyesnot found in the text
Terms restrict benchmarkingyesnot found in the text
Terms or service can change without noticeyesnot found in the text
Arbitration or class-action waivernot found in the textnot found in the text

Verdicts

Amazon Nova 2 Sonic

Nova 2 Sonic runs speech-to-speech conversations with asynchronous tools on Bedrock, with IAM scoping, no default storage of inputs and a 99.9 per cent SLA. Sessions cut off at 8 minutes, the Python SDK is pre-alpha, and the event payloads have no schema file. Prices are in a script-drawn table we couldn't read.

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.

Before you call either

Amazon Nova 2 Sonic

  1. Plan a reconnect before 8 minutes and replay chat history (up to 200 KB) at the start of the new session
  2. Send session, prompt and content start events in order before any audio
  3. Make tool calls safe to repeat, since a reconnect can replay them
  4. Back off on ThrottlingException and stay within 20 concurrent sessions per Region
  5. Use the polyglot voices TIFFANY or MATTHEW when callers may switch language

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

Questions

Which is better for AI agents, Amazon Nova 2 Sonic or Inworld Realtime API?

Amazon Nova 2 Sonic scores 67.6 (B) on agent readiness against Inworld Realtime API's 60.1 (C), and leads in 4 of 7 scored categories. Inworld Realtime API leads on payments & pricing and maintenance & community.

Do Amazon Nova 2 Sonic and Inworld Realtime API need an API key?

Both need an API key.

Can an agent call Amazon Nova 2 Sonic and Inworld Realtime API without installing anything?

No hosted endpoint is listed for Amazon Nova 2 Sonic. No hosted endpoint is listed for Inworld Realtime API.

Other comparisons with Amazon Nova 2 Sonic or Inworld Realtime API

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