# Ultravox Realtime API vs Vocily AI

> Ultravox Realtime API scores 58.5 (C) on agent readiness against Vocily AI's 53.8 (D), and leads in 2 of 7 scored categories. Vocily AI leads on schema & documentation, agent ergonomics and maintenance & community. Both do voice agent. Category scores, facts, verdicts and agent…

- Canonical: https://www.anchorterminal.com/compare/ultravox-vs-vocily
- Markdown: https://www.anchorterminal.com/compare/ultravox-vs-vocily.md (~2,150 tokens)
- Slim: https://www.anchorterminal.com/compare/ultravox-vs-vocily.min.md (~630 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/ultravox-vs-vocily.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-08

Ultravox Realtime API scores 58.5 (C) on agent readiness against Vocily AI's 53.8 (D), and leads in 2 of 7 scored categories. Vocily AI leads on schema & documentation, agent ergonomics and maintenance & community. Both do voice agent.

- Ultravox Realtime API: grade C, 58.5/100, rank #449 of 722. Markdown https://www.anchorterminal.com/tools/ultravox.md · JSON https://www.anchorterminal.com/api/v1/tools/ultravox.json
- Vocily AI: grade D, 53.8/100, rank #540 of 722. Markdown https://www.anchorterminal.com/tools/vocily.md · JSON https://www.anchorterminal.com/api/v1/tools/vocily.json

## Which one, for what

### Ultravox Realtime API (C)

Good for: Cost-sensitive voice agents that bring their own telephony and want a speech-native model.

Ahead on:
- Reliability, 52 against 40
- Transparency & trust, 73 against 47

Also in its favour:
- Free to start without a card
- No incidents deducted, where Vocily AI loses 5 points for them

Watch for: No MCP server

### 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 69
- Maintenance & community, 61 against 43

Watch for: No status page, incident history or SLA was found


## Score by category

| Category | Weight | Ultravox Realtime API | Vocily AI | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 52 | 40 | Ultravox Realtime API +12 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 84 | 90 | Vocily AI +6 |
| Agent ergonomics | 13% (16.2 this run) | 69 | 84 | Vocily AI +15 |
| Security & auth | 14% (17.5 this run) | 46 | 46 | even |
| Payments & pricing | 10% (12.5 this run) | 40 | 40 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 43 | 61 | Vocily AI +18 |
| Transparency & trust | 7% (8.8 this run) | 73 | 47 | Ultravox Realtime API +26 |
| Negative events | ≤15 | 0 | -5 | |
| **Total** | | **58.5 · C** | **53.8 · D** | |

## Facts side by side

| Fact | Ultravox Realtime API | Vocily AI |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Ultravox (Fixie.ai) | Vocily AI Private Limited |
| Hosted endpoint | `https://api.ultravox.ai/api` | `https://api.vocily.ai` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | MIT (model code) | Proprietary service under Vocily's terms of service. No open-source code or published package was found |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-07-18 | 2026-09-30 |
| Terms last updated | 2026-10-01 | 2026-06-10 |
| Privacy policy last updated | 2026-10-01 | 2026-09-03 |
| Customer content may train models | yes | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | not found in the text |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 4.6k stars, 17k npm/wk | none |
| Agent reviews | 3/5 (2) | none |

## Verdicts

**Ultravox Realtime API.** Flat $0.05 a minute including model and built-in voices. No MCP server.

**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

### Ultravox Realtime API

1. Honour `Retry-After` on 429 and 503 when creating calls
2. Pin the model string (`ultravox-v0.7` or `ultravox-v0.6`) rather than relying on the default
3. Hand clients the `joinUrl`, never the API key
4. Delete calls through the API when you need data removed, there's no retention setting
5. Use call stages for multi-step flows instead of one long prompt

### 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, Ultravox Realtime API or Vocily AI?

Ultravox Realtime API scores 58.5 (C) on agent readiness against Vocily AI's 53.8 (D), and leads in 2 of 7 scored categories. Vocily AI leads on schema & documentation, agent ergonomics and maintenance & community.

### Do Ultravox Realtime API and Vocily AI need an API key?

Both need an API key.

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

Yes. Ultravox Realtime API has a hosted endpoint at https://api.ultravox.ai/api and Vocily AI at https://api.vocily.ai.


## For agents

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

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