Fixie

Fixie, now operating as Ultravox, builds real‑time speech‑native voice AI platforms. The company provides developer‑friendly APIs that enable fast, natural conversational experiences, offering primitives for voice agents, pricing tiers, and extensive documentation. Backed by Redpoint Ventures, Ultravox focuses on research and product development to accelerate speech‑to‑speech AI capabilities.

Fixie is listed with 1 API on the APIs.io network. Tagged areas include Company, VoiceAI, RealTime, SpeechNative, and DeveloperAPI.

Fixie’s developer surface includes pricing, engineering blog, and 10 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

20.7/100 emerging Agent 0/100 human only Full breakdown ↓
scored 2026-10-31 · rubric v0.25.0 · Show this score on your site →

1 API

CompanyVoiceAIRealTimeSpeechNativeDeveloperAPI

Kin Score

Kin Score How this is scored →
scored 2026-10-31 · rubric v0.25.0

Composite quality — 20.7/100 · emerging

Contract Quality 0.0 / 21

Developer Ergonomics 1.6 / 17

Access Clarity 10.7 / 17

Operational Transparency 0.6 / 11

Contract Governance 0.0 / 10

Discoverability 4.9 / 9

Regulatory Posture 2.1 / 15

Agent readiness — 0/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Machine-Readable Contract +18 pts — api_specs includes an OpenAPI document
MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0

13 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 0.0 — up to +25.0 composite points
Developer Ergonomics scores 9.5 — up to +18.1 composite points
Operational Transparency scores 5.3 — up to +12.3 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/fixie-ai/apis.yml: open an issue on github.com/api-evangelist/fixie-ai to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 1

Individual APIs this provider publishes, each with its own machine-readable definition.

Fixie API

Fixie (operating as Ultravox) offers a developer‑friendly voice AI platform, but no machine‑readable API contract was found.

Pricing Plans 1

Published pricing tiers and plan structures.

Fixie Ai Plans Pricing

3 plans

PLANS

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Fixie Ai Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Resources

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

Build 3

SDKs, sample code, and the tooling you integrate with

SDKs

SDKs

Packages

Packages

GitHubOrganization

GitHubOrganization

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Commercial 4

Pricing, plans, and the legal terms of use

Plans

TermsOfService

PrivacyPolicy

Pricing

Company 2

The organization behind the API

Blog

Blog

Website

Website

Other 1

Properties that don't map to a standard resource type

Hosts

Hosts

Source (apis.yml)

aid: fixie-ai
name: Fixie
image: https://framerusercontent.com/images/NU41PDn8R4zag1RapkCZFTCTOxM.jpg
description: Fixie, now operating as Ultravox, builds real‑time speech‑native voice AI platforms. The company provides developer‑friendly
  APIs that enable fast, natural conversational experiences, offering primitives for voice agents, pricing tiers, and extensive
  documentation. Backed by Redpoint Ventures, Ultravox focuses on research and product development to accelerate speech‑to‑speech
  AI capabilities.
url: https://raw.githubusercontent.com/api-evangelist/fixie-ai/refs/heads/main/apis.yml
x-type: company
x-source: harvest:vc-portfolio
x-tier: profiled
x-tier-reason: enrichment pass 2026-10-23 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-10-23'
modified: '2026-10-23'
tags:
- Company
- VoiceAI
- RealTime
- SpeechNative
- DeveloperAPI
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Plans
  url: plans/fixie-ai-plans-pricing.yml
- type: LLMsTxt
  url: llms/fixie-ai-llms.txt
- type: Hosts
  url: hosts/fixie-ai-hosts.yml
- type: SDKs
  url: packages/fixie-ai-packages.yml
- type: Packages
  url: packages/fixie-ai-packages.yml
- type: TermsOfService
  url: https://www.ultravox.ai/terms
- type: PrivacyPolicy
  url: https://www.ultravox.ai/privacy
- type: Pricing
  url: https://www.ultravox.ai/pricing
- type: GitHubOrganization
  url: https://github.com/fixie-ai
- type: Blog
  url: https://www.ultravox.ai/blog
- type: DomainSecurity
  url: security/fixie-ai-domain-security.yml
- type: Website
  url: https://www.fixie.ai/
apis:
- name: Fixie API
  description: Fixie (operating as Ultravox) offers a developer‑friendly voice AI platform, but no machine‑readable API contract
    was found.
  humanURL: https://www.ultravox.ai/
  aid: fixie-ai:fixie-api
x-backed-by:
- redpoint-ventures
x-enrichment:
  date: '2026-10-23'
  status: enriched
  artifacts_added: 12
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

Fixie API — frequently asked questions

Does Fixie have an API?

Yes. APIs.io lists 1 API from Fixie, including Fixie API.

How much does the Fixie API cost?

APIs.io lists 3 pricing plans for Fixie, with each plan's price, limits and inclusions under Pricing Plans on this page.

Is the Fixie API ready for AI agents?

Fixie has a Kin Score of 20.7 out of 100 (emerging) and an Agent Readiness score of 0.0 (human-only), scored by API Evangelist on 2026-10-31.

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