# Amazon Nova 2 Sonic vs Inworld Realtime API

> Amazon Nova 2 Sonic scores 67.6 (B) to Inworld Realtime's 60.1 (C) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-inworld-realtime
- Markdown: https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-inworld-realtime.md (~5,250 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

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.

- Amazon Nova 2 Sonic: grade B, 67.6/100, rank #315 of 1510. Markdown https://www.anchorterminal.com/tools/amazon-nova-sonic.md · JSON https://www.anchorterminal.com/api/v1/tools/amazon-nova-sonic.json
- Inworld Realtime API: grade C, 60.1/100, rank #671 of 1510. Markdown https://www.anchorterminal.com/tools/inworld-realtime.md · JSON https://www.anchorterminal.com/api/v1/tools/inworld-realtime.json
- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md
- All 518 voice agents comparisons: https://www.anchorterminal.com/compare/voice-agents/index.md

## Which one, for what

### Amazon Nova 2 Sonic (B)

Good 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)

Good 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

### 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

| Category | Weight | Amazon Nova 2 Sonic | Inworld Realtime API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 95 | 62 | Amazon Nova 2 Sonic +33 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 75 | 60 | Amazon Nova 2 Sonic +15 |
| Agent ergonomics | 13% (16.2 this run) | 64 | 68 | Inworld Realtime API +4 |
| Security & auth | 14% (17.5 this run) | 77 | 58 | Amazon Nova 2 Sonic +19 |
| Payments & pricing | 10% (12.5 this run) | 10 | 40 | Inworld Realtime API +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 50 | 71 | Inworld Realtime API +21 |
| Transparency & trust | 7% (8.8 this run) | 79 | 63 | Amazon Nova 2 Sonic +16 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **67.6 · B** | **60.1 · C** | |

## Facts side by side

| Fact | Amazon Nova 2 Sonic | Inworld Realtime API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Amazon Web Services | Inworld AI |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | HTTP | websocket, HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| Price for voice agents | not published | $25 per 1M characters |
| x402 | no | no |
| Tools exposed | 0 | 0 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-05-28 | 2026-10-16 |
| Terms last updated | 2026-10-01 | 2025-06-11 |
| Privacy policy last updated | 2026-05-18 | 2026-01-18 |
| Customer content may train models | yes, with an opt-out | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | not found in the text | not 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.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-inworld-realtime.json, and with the fewest tokens: https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-inworld-realtime.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "amazon-nova-sonic", "b": "inworld-realtime"}`. From a terminal: `anchor compare amazon-nova-sonic inworld-realtime`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/amazon-nova-sonic.json and https://www.anchorterminal.com/api/v1/tools/inworld-realtime.json

## Other comparisons with Amazon Nova 2 Sonic or Inworld Realtime API

- [Amazon Nova 2 Sonic vs AssemblyAI Voice Agent API](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-assemblyai-voice-agent.md)
- [Amazon Nova 2 Sonic vs Bland AI API + MCP](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-bland-ai.md)
- [Amazon Nova 2 Sonic vs Bolna API + MCP](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-bolna.md)
- [Amazon Nova 2 Sonic vs Deepgram Voice Agent API](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-deepgram-voice-agent.md)
- [Amazon Nova 2 Sonic vs ElevenLabs Agents API + MCP](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-elevenlabs-agents.md)
- [Amazon Nova 2 Sonic vs fone.me](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-fone-me.md)
- [Amazon Nova 2 Sonic vs Gemini Live API](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-gemini-live.md)
- [Amazon Nova 2 Sonic vs GPT-Live](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-gpt-live.md)
- [Amazon Nova 2 Sonic vs Harmony.ai](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-harmony-ai.md)
- [Amazon Nova 2 Sonic vs Hume EVI (Empathic Voice Interface)](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-hume-evi.md)
- [Amazon Nova 2 Sonic vs LiveKit Agents](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-livekit-agents.md)
- [Amazon Nova 2 Sonic vs OpenAI Realtime API](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-openai-realtime.md)
- [Amazon Nova 2 Sonic vs Pipecat](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-pipecat.md)
- [Amazon Nova 2 Sonic vs PlaceCall](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-placecall.md)
- [Amazon Nova 2 Sonic vs Retell AI API + MCP](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-retell-ai.md)
- [Amazon Nova 2 Sonic vs Rime Prism](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-rime-prism.md)
- [Amazon Nova 2 Sonic vs Synthflow API + MCP](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-synthflow.md)
- [Amazon Nova 2 Sonic vs Ultravox Realtime API](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-ultravox.md)
- [Amazon Nova 2 Sonic vs Vaani Developer Platform](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-vaani-voice.md)
- [Amazon Nova 2 Sonic vs Vapi API + MCP](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-vapi.md)
- [Amazon Nova 2 Sonic vs Vocily AI](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-vocily.md)
- [Amazon Nova 2 Sonic vs Vogent API](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-vogent.md)
- [AssemblyAI Voice Agent API vs Inworld Realtime API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-inworld-realtime.md)
- [Bland AI API + MCP vs Inworld Realtime API](https://www.anchorterminal.com/compare/bland-ai-vs-inworld-realtime.md)
- [Bolna API + MCP vs Inworld Realtime API](https://www.anchorterminal.com/compare/bolna-vs-inworld-realtime.md)
- [Deepgram Voice Agent API vs Inworld Realtime API](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-inworld-realtime.md)
- [ElevenLabs Agents API + MCP vs Inworld Realtime API](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-inworld-realtime.md)
- [fone.me vs Inworld Realtime API](https://www.anchorterminal.com/compare/fone-me-vs-inworld-realtime.md)
- [Gemini Live API vs Inworld Realtime API](https://www.anchorterminal.com/compare/gemini-live-vs-inworld-realtime.md)
- [GPT-Live vs Inworld Realtime API](https://www.anchorterminal.com/compare/gpt-live-vs-inworld-realtime.md)
- [Harmony.ai vs Inworld Realtime API](https://www.anchorterminal.com/compare/harmony-ai-vs-inworld-realtime.md)
- [Hume EVI (Empathic Voice Interface) vs Inworld Realtime API](https://www.anchorterminal.com/compare/hume-evi-vs-inworld-realtime.md)
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- [Inworld Realtime API vs OpenAI Realtime API](https://www.anchorterminal.com/compare/inworld-realtime-vs-openai-realtime.md)
- [Inworld Realtime API vs Pipecat](https://www.anchorterminal.com/compare/inworld-realtime-vs-pipecat.md)
- [Inworld Realtime API vs PlaceCall](https://www.anchorterminal.com/compare/inworld-realtime-vs-placecall.md)
- [Inworld Realtime API vs Retell AI API + MCP](https://www.anchorterminal.com/compare/inworld-realtime-vs-retell-ai.md)
- [Inworld Realtime API vs Rime Prism](https://www.anchorterminal.com/compare/inworld-realtime-vs-rime-prism.md)
- [Inworld Realtime API vs Synthflow API + MCP](https://www.anchorterminal.com/compare/inworld-realtime-vs-synthflow.md)
- [Inworld Realtime API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/inworld-realtime-vs-ultravox.md)
- [Inworld Realtime API vs Vaani Developer Platform](https://www.anchorterminal.com/compare/inworld-realtime-vs-vaani-voice.md)
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- [Inworld Realtime API vs Vocily AI](https://www.anchorterminal.com/compare/inworld-realtime-vs-vocily.md)
- [Inworld Realtime API vs Vogent API](https://www.anchorterminal.com/compare/inworld-realtime-vs-vogent.md)
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