# Amazon Nova 2 Sonic vs Harmony.ai

> Amazon Nova 2 Sonic scores 67.6 (B) to Harmony.ai's 43.4 (E) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-11-07

Amazon Nova 2 Sonic scores 67.6 (B) on agent readiness against Harmony.ai's 43.4 (E), and leads in 4 of 7 scored categories. Harmony.ai leads on payments & pricing. Both do voice agents.

- Amazon Nova 2 Sonic: grade B, 67.6/100, rank #314 of 1486. Markdown https://www.anchorterminal.com/tools/amazon-nova-sonic.md · JSON https://www.anchorterminal.com/api/v1/tools/amazon-nova-sonic.json
- Harmony.ai: grade E, 43.4/100, rank #1234 of 1486. Markdown https://www.anchorterminal.com/tools/harmony-ai.md · JSON https://www.anchorterminal.com/api/v1/tools/harmony-ai.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 18
- Security & auth, 77 against 48
- Maintenance & community, 50 against 42
- Transparency & trust, 79 against 55

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

### Harmony.ai (E)

Good 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:
- Payments & pricing, 15 against 10

Also in its favour:
- A hosted endpoint, with nothing to install

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


## Why the edge

### Reliability: Amazon Nova 2 Sonic +77

- 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.
- Harmony.ai (18): Graded on the Public API and MCP server at api.harmony.ai, read with the hosted lines. status.harmony.ai exists but is a static page. "All systems operational", "Last checked · just now", the uptime figures and the 90-day bars are fixed in the HTML from a date of 17 August 2026, and the subscribe form sends nothing. It isn't linked from harmony.ai or the docs, so it scores as no status page (0) and no readable history (5). The docs say "The API has no published rate limits yet". Pro's 10 concurrent calls and 100 calls a day are the only numbers (5 of 15). No 429 or Retry-After guidance, but the errors page says which writes are safe to retry and which can place a second call, and how to check before resending (8 of 15). No SLA found (0). The API is in beta (OpenAPI version 1.0.0-beta.1, and the versioning page has a "During the beta" section) (0).

### Security & auth: Amazon Nova 2 Sonic +29

- 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.
- Harmony.ai (48): Revocable Bearer keys, shown once, with a last-used time, but no scopes, no expiry and the full access of the user who made them. Keys never travel in a URL (20 of 30). The MCP server is read-only, but a REST key can import contacts into workflows that place real calls, with no read-only key (8 of 20). The MCP docs say tool results carry text from contacts and teammates and tell the user to treat it as untrusted input (10 of 15). Request IDs on every response and key last-used times. No audit log of account actions documented (6 of 15). harmony.ai/.well-known/security.txt returns 404. The trust page claims SOC 2 Type II, ISO 27001, an annual pen test and a public disclosure programme with bounties, but names no auditor, report, certificate or contact, and shares reports only under NDA (4 of 20).

### Transparency & trust: Amazon Nova 2 Sonic +24

- 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.
- Harmony.ai (55): Closed service with conflicting terms. The Terms of Service are One AI Inc.'s, undated, referring to oneai.com sites and pricing, while the DPA of 10 September 2026 names monday.com Ltd. and incorporates monday.com's Terms of Service (7 of 30). Data handling statements disagree. The privacy policy (24 August 2026) keeps data while the account is active and says data may be used to train One AI's systems. The trust page says retention is configurable with no cross-customer training. The terms say all calls are recorded unless the customer opts out in writing, and the trust page lists US, EU and APAC regions while the sub-processor page lists US and EU. The DPA commits to deletion or return at termination (10 of 30). The versioning page keeps an old major version for at least 12 months after a new one, once the API is generally available (10 of 20). Nine sub-processors named with hosting regions, with a seven-day objection window in the DPA (18 of 20).

### Maintenance & community: Amazon Nova 2 Sonic +8

- 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.
- Harmony.ai (42): Read for a closed service. The press page dates the launch to October 2026, within 30 days (30). No changelog or dated releases (0). Support is through a contact form and the docs' request ID guidance, with no public changelog or community channel found (4 of 15). A hosted MCP server, not in the official registry, and no SDK (5 of 15). No package to assess (3 of 10).

### Payments & pricing: Harmony.ai +5

- 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.
- Harmony.ai (15): No x402, MPP or L402 (0 of 40). Pro is $0.39 a minute plus a $250 monthly platform fee, published without a login, with the minute rate varying by voice model and a custom implementation fee (15 of 20). A Try for free signup is linked, with no trial terms on public pages and the signup not tried, so no free tier is counted (0). A person signs up in a browser and creates keys in the web app (0).

## Score by category

| Category | Weight | Amazon Nova 2 Sonic | Harmony.ai | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 95 | 18 | Amazon Nova 2 Sonic +77 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 75 | 77 | Harmony.ai +2 |
| Agent ergonomics | 13% (16.2 this run) | 64 | 65 | Harmony.ai +1 |
| Security & auth | 14% (17.5 this run) | 77 | 48 | Amazon Nova 2 Sonic +29 |
| Payments & pricing | 10% (12.5 this run) | 10 | 15 | Harmony.ai +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 50 | 42 | Amazon Nova 2 Sonic +8 |
| Transparency & trust | 7% (8.8 this run) | 79 | 55 | Amazon Nova 2 Sonic +24 |
| Negative events | ≤15 | 0 | -2 | |
| **Total** | | **67.6 · B** | **43.4 · E** | |

## Facts side by side

| Fact | Amazon Nova 2 Sonic | Harmony.ai |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Amazon Web Services | monday.com Ltd. (Harmony.ai) |
| Hosted endpoint | no (local only) | `https://api.harmony.ai` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Paid |
| Price for voice agents | not published | $0.39 per minute of call |
| x402 | no | no |
| Licence | none | Proprietary 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 found |
| Tools exposed | 0 | 6 |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| Last release | 2026-05-28 | none |
| Terms last updated | 2026-10-01 | no date given |
| Privacy policy last updated | 2026-05-18 | 2026-08-24 |
| 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 | yes |
| Arbitration or class-action waiver | not found in the text | yes |
| Agent reviews | none | 2.3/5 (4) |

## How the scores have moved

### Amazon Nova 2 Sonic

No score change since it was listed.

### Harmony.ai

- -0.2 on 30 October 2026: checklist
- +0.1 on 27 October 2026: checklist

## 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.

**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.

## 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

### 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

## Questions

### Which is better for AI agents, Amazon Nova 2 Sonic or Harmony.ai?

Amazon Nova 2 Sonic scores 67.6 (B) on agent readiness against Harmony.ai's 43.4 (E), and leads in 4 of 7 scored categories. Harmony.ai leads on payments & pricing.

### Do Amazon Nova 2 Sonic and Harmony.ai need an API key?

Both need an API key.

### Can an agent call Amazon Nova 2 Sonic and Harmony.ai without installing anything?

No hosted endpoint is listed for Amazon Nova 2 Sonic. Harmony.ai has a hosted endpoint at https://api.harmony.ai.


## For agents

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

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- [Harmony.ai vs Hume EVI (Empathic Voice Interface)](https://www.anchorterminal.com/compare/harmony-ai-vs-hume-evi.md)
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