# Fixie

**Canonical:** https://apis.io/providers/fixie/  
**Website:** https://ultravox.ai/  
**APIs profiled:** 1

Fixie is the company behind Ultravox Realtime, a speech-native voice AI platform for building natural, low-latency conversational voice agents. Rather than transcribing speech to text first, Ultravox processes audio directly to preserve tone, cadence, and pitch while cutting latency. The Ultravox Realtime REST API (api.ultravox.ai) lets developers create reusable agents, start and manage calls, define custom and built-in tools, clone and manage voices, build RAG corpora, wire telephony (Twilio, Telnyx, Plivo, SIP), and subscribe to call-lifecycle webhooks. Client SDKs ship for JavaScript, Python, Flutter/Dart, React Native, Kotlin/Android, and Swift/iOS. Fixie was backed by Redpoint Ventures; fixie.ai now redirects to ultravox.ai and its open models are published under the fixie-ai organization on Hugging Face.

## Kin Score — 50.1 / 100 (developing)

Scored 2026-08-30 under rubric 0.17.2. Trend: flat (-0.6 from 50.7).

| Facet | Score |
|---|---|
| Discoverability | 75.9 |
| Contract Quality | 55.3 |
| Governance | 4.5 |
| Contract Governance | 4.5 |
| Operational Transparency | 34.2 |
| Developer Ergonomics | 66.1 |
| Commercial Clarity | 52.6 |
| Access Clarity | 52.6 |

## Agent readiness — 27.9 (agent-aware)

| Dimension | Value |
|---|---|
| Spec Presence | yes |
| Agentic Access | derived |
| Reversibility Documented | no |
| MCP Server | no |
| Auth Clarity | bearer |
| Idempotency | no |
| Error Semantics | documented |
| OpenAPI Examples | partial |
| Rate Limit Signal | no |
| Event Surface Described | yes |
| Agent Skills | derived |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | no |
| Delegated Identity | no |
| Protected Resource Metadata | no |
| Dynamic Client Registration | no |
| Agentic Commerce | no |

## Access

Self-serve signup — onboarding: self-serve, pricing: unknown, trial: no (confidence: medium).

## APIs (14)

- **Fixie accounts API** — The accounts API from Fixie — 9 operation(s) for accounts.
- **Fixie agents API** — The agents API from Fixie — 9 operation(s) for agents.
- **Fixie api_keys API** — The api_keys API from Fixie — 2 operation(s) for api_keys.
- **Fixie call_throttles API** — The call_throttles API from Fixie — 2 operation(s) for call_throttles.
- **Fixie calls API** — The calls API from Fixie — 13 operation(s) for calls.
- **Fixie corpora API** — The corpora API from Fixie — 8 operation(s) for corpora.
- **Fixie deleted_calls API** — The deleted_calls API from Fixie — 2 operation(s) for deleted_calls.
- **Fixie models API** — The models API from Fixie — 1 operation(s) for models.
- **Fixie schema API** — The schema API from Fixie — 1 operation(s) for schema.
- **Fixie sip API** — The sip API from Fixie — 3 operation(s) for sip.
- **Fixie telephony_configs API** — The telephony_configs API from Fixie — 3 operation(s) for telephony_configs.
- **Fixie tools API** — The tools API from Fixie — 4 operation(s) for tools.
- **Fixie voices API** — The voices API from Fixie — 4 operation(s) for voices.
- **Fixie webhooks API** — The webhooks API from Fixie — 2 operation(s) for webhooks.

## MCP servers (1)

- **Fixie MCP Server**

## Agentic access (1)

- **Fixie Agentic Access** — 114 operations · 57 acting

## Security (3)

- **Fixie Authentication** — apiKey · 1 scheme
- **Fixie Domain Security** — TLSv1.3 · HSTS · DMARC
- **Fixie Trust Center** — trust center published

## Tags

Company, Voice AI, Conversational AI, Real-Time, Speech, Agents, Telephony, Machine-Learning, SIP, Webhook

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/fixie/). Scores are computed from the provider's own public artifacts under a published rubric.