Ultravox Realtime API vs Vaani Developer Platform

Ultravox Realtime API 74

The Ultravox model code is MIT on GitHub, and the v0.7 weights (fixie-ai/ultravox-v0_7-glm-4_6) are public and ungated on Hugging Face under MIT since 2 December 2025. The hosted service is closed (26 of 30). The privacy policy (22 May 2025) says voice data and audio aren't used to train or fine-tune Ultravox's models, but keeps data for as long as the account exists, with call deletion through the API (15 of 30). A deprecation guide with a minimum 30-day window for pre-release capabilities and dated removals, such as the Qwen3 preview model on 22 December 2025 (18 of 20). Hosting in the United States is stated, with no subprocessor list found (8 of 20).

Vaani Developer Platform 42

A closed service. The terms name Vaani AI Research Private Limited, its Bengaluru address, CIN, Indian law and Bengaluru courts, but they're undated, written for the website www.vaaniresearch.com, and say nothing on billing, refunds, API use or customer data. The SDK and MCP server are MIT, with the SDK's full source in its PyPI sdist (14 of 30). The privacy policy (undated) keeps data, including voice recordings, for up to 24 months, while the pricing table gives 30 days' retention on pay as you go and zero retention on Enterprise. Voice data trains models only with explicit consent. No DPA found (8 of 30). No deprecation policy. The privacy policy promises 15 days' notice of significant changes, and the terms allow changes and termination without notice (2 of 20). The privacy policy names vendor categories (cloud hosting, analytics, voice transcription) and says data may be stored outside India. Model and telephony providers can be read from the calculator, and India data residency is offered on demand. No subprocessor list or data location for the hosted service (5 of 20). 14+8+2+5 = 29.

Ultravox Realtime API 84

OpenAPI schema at api.ultravox.ai/api/schema/ (25). llms.txt with Markdown copies (10). Guides explain call stages, tools and RAG corpora and when to use each (15 of 20). The OpenAPI types call creation with enums and required fields (13 of 15). Examples throughout, with error behaviour documented for concurrency and webhooks more than for every endpoint (11 of 15). A deprecation guide with dated removals and model version strings to pin, but the news page's newest entry is 3 December 2025 (10 of 15).

Vaani Developer Platform 57

A public OpenAPI 3.1 file at docs.vaani.dev/api-reference/openapi.json, version 2.0.0, but it holds 5 of the 24 operations in the API reference (trigger-call, call history, transcript, stream, call details). It declares the key only as a header parameter with no security scheme, its trigger-call schema leaves out medium and modify_agent, and four response schemas are empty. The MCP tools have typed zod inputs (8 of 25). llms.txt, llms-full.txt and a Markdown copy of each page on Mintlify (10). Pages explain what each route is for and warn where it matters, such as dispatch acceptance not meaning a completed call, transcripts returning 404 while processing, and real paid calls from trigger_call (14 of 20). Ranges and enums are documented (medium, voice_speed 0.6 to 1.4, page_size up to 200, campaign retries 1 to 10, campaign status), but metadata, modify_agent and three MCP tool payloads are free-form objects (9 of 15). Request examples in cURL, Python and JavaScript on every endpoint, a campaign error-code table, 422 and 404 bodies and an SDK exception table by status. No single error reference for the whole API (12 of 15). The docs state API version 2.0.0, but no changelog or release notes page was found (4 of 15). 8+10+14+9+12+4 = 57.

Ultravox Realtime API 52

A status page sits at status.ultravox.ai, but its robots rules blocked our reader on 1 and 2 October, robots.txt included, so we couldn't confirm components or history (10 of 20 for the page, 5 for unreadable history). Concurrency is published, 5 calls on pay as you go, no hard cap on Pro, and priority for up to 100 calls on Scale (15). Over-limit requests get 429, Scale accounts below their priority level get 503, and both carry a Retry-After header with exponential-backoff guidance. No idempotency guidance for call creation (12 of 15). No SLA found (0). The Realtime API is generally available (10).

Vaani Developer Platform 28

Graded on the hosted REST API at api.vaanivoice.ai. No status page. status.vaani.dev and status.vaanivoice.ai don't resolve, and neither the site nor the docs link one (0). With no history to read, 5. No request rate limits are published. The docs give 2 concurrent calls on pay as you go and a per-organisation campaign concurrency cap, so partial credit (5). The SDK raises RateLimitError on 429 and the MCP client retries once after 600 ms, but no Retry-After, backoff guidance or idempotency key for call creation is documented (3). The pricing table lists a 99.50 per cent uptime SLA on both plans, but no SLA document or service credits were found and the terms supply the service "as-is" with no warranties, so half (5). The API is version 2.0.0 and isn't labelled beta (10). 0+5+5+3+5+10 = 28.

Ultravox Realtime API 40

No x402, MPP or L402 (0 of 40). $0.05 a minute, SIP at 0.5 cents and Pro at $100 a month are on the public pricing page (20). 30 free minutes with no card, per last week's check (20). Access starts with a human signup (0).

Vaani Developer Platform 22

No x402, MPP or L402 (0 of 40). The ₹1 ($0.02) a minute platform fee, number rental, concurrency lines and add-ons are public, and the calculator shows each provider's unit rate without a login. Registry checks, extraction and evaluations "can add separate charges" that aren't priced, and the billing pulse depends on the account, so 3 off (17 of 20). The home page says "Start free on Vaani's Platform", but the pricing page states a prepaid wallet with no free credit, trial minutes or card rule, and we didn't sign up to check, so 5 of 20. A person signs up with email verification at platform.vaani.dev and creates keys in the dashboard (0). 0+17+5+0 = 22.

Ultravox Realtime API 43

The JavaScript client, ultravox-client 0.6.0, reached npm on 18 July 2026, 76 days before the check, with CI publishing and npm provenance. The newest platform change on the news and deprecation pages is the move to ultravox-v0.7 on 22 December 2025 (20). One release in the last 90 days. An official example added on 28 and 29 September 2026 creates Inworld TTS 2 voices with pronunciation dictionaries through /api/voices, which no news entry announces, so we didn't count it (0). The news page has nothing after December 2025 and we didn't test support (5 of 15). Client SDKs for six platforms. JavaScript is current, the Python client's last release is 0.1.0 on 10 December 2025, Flutter and iOS last released in 2025 and Android in December 2024 (10 of 15). The JavaScript client runs CI and publishes from it, and the Python client needs 3.10 or later (8 of 10).

Vaani Developer Platform 59

vaani-research-mcp 0.1.1 on 2026-10-14 (30). In the last 90 days, vaani-sdk 0.3.1 on 28 September and three npm versions (0.0.0-stage, 0.1.0, 0.1.1) within 40 minutes on 14 October. No dated changelog, so half (10 of 20). A closed service with no public changelog, issue tracker or community channel found. Contact is hello@vaaniresearch.com and a booking link, and we didn't test whether they answer. The MCP repository on GitHub couldn't be read from this session (4 of 15, the closed-service reading). A current official Python SDK, released seven times since April 2026. The MCP server isn't in the official MCP registry (10 of 15). The SDK's sdist ships its tests and current httpx and pydantic dependencies, and the MCP package runs its tests before publishing, but no public CI was found and the SDK has no repository (5 of 10). 30+10+4+10+5 = 59.

Ultravox Realtime API 69

Scored as an API, since there's no MCP server. Calls and messages list with cursors and page sizes (18 of 25). Paging and filters on calls (17 of 20). 429 and 503 come with Retry-After, which an agent can act on (14 of 20). No idempotency keys on call creation (5 of 20). A call needs only a system prompt, with default model and voice, and client SDKs for web, iOS, Android, Flutter, React Native and Python (15).

Vaani Developer Platform 64

The local MCP server loads 9 compact tools, and VAANI_READ_ONLY=true leaves 3. Transcripts are cut at 20,000 characters by default with a note. The REST API has no field selection or summaries, so 3 off (22 of 25). Call history pages by page and page_size up to 200 with no filters. The MCP agent filter runs client-side on one page. Agents filter by search and published_only and campaigns by status (12 of 20). Campaign errors carry a machine-readable code, a message, the path and a request_id (shown as "unknown" in the example). Validation errors list the field location, the SDK maps each status to a typed exception including 402 for a low wallet, and the MCP server adds a hint per status (15 of 20). All 9 MCP tools carry readOnlyHint, destructiveHint and idempotentHint, with trigger_call and campaign_action marked destructive. No idempotency key on trigger-call, and the MCP client retries a POST once after a timeout or 5xx, so a call can be placed twice. The webhook docs say to deduplicate by event id (8 of 20). A call needs agent_id, contact_number and name, with medium defaulting to telephony. One official SDK, Python, sync and async. The npm package is an MCP server, not an SDK (7 of 15). 22+12+15+8+7 = 64.