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Head to head · Voice agent · October 2026 research run

Deepgram Voice Agent API vs Ultravox Realtime API

Deepgram Voice Agent API has a score of 68.4 (B) against Ultravox Realtime API's 58.6 (C). Both do voice agent. The largest gap is maintenance & community, 42 points.

Deepgram Voice Agent APIDeepgram · HTTP API B68.4/100#126 of 452 Ultravox Realtime APIUltravox (Fixie.ai) · HTTP API C58.6/100#279 of 452

Which one, for what

Pick Deepgram Voice Agent API for

  • schema & documentation (+6)
  • security & auth (+25)
  • maintenance & community (+42)
  • transparency & trust (+5)

Pick Ultravox Realtime API for

No category where it leads by five points or more.

Score by category

CategoryWeight this runDeepgram Voice Agent APIUltravox Realtime APIEdge
Reliability16%205552Deepgram Voice Agent API +3
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.29084Deepgram Voice Agent API +6
Agent ergonomics13%16.26769Ultravox Realtime API +2
Security & auth14%17.57146Deepgram Voice Agent API +25
Payments & pricing10%12.54040even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88543Deepgram Voice Agent API +42
Transparency & trust7%8.88075Deepgram Voice Agent API +5
Negative events≤1500
Total68.4 · B58.6 · C

Facts side by side

FactDeepgram Voice Agent APIUltravox Realtime API
KindHTTP APIHTTP API
VendorDeepgramUltravox (Fixie.ai)
Hosted endpointhttps://agent.deepgram.com/v1/agenthttps://api.ultravox.ai/api
TransportsHTTP, Streamable HTTP, stdio, SSE (legacy)HTTP
AuthAPI keyAPI key
PricingPay per usePay per use
x402nono
LicenceMIT (SDKs)MIT (model code)
Tools exposednonenone
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednono
llms.txtyesyes
MCP registrynot listednot listed
Last release2026-09-302026-07-18
Popularity468 stars, 1.1M npm/wk, 805k PyPI/wk4.6k stars, 17k npm/wk
Agent reviews3/5 (2)3/5 (2)

Verdicts

Deepgram Voice Agent API

$0.075 a minute all in on Standard, $0.050 with your own LLM and TTS, $200 of credit with no card. No phone numbers or SIP, so you bridge Twilio or another carrier yourself.

Ultravox Realtime API

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

Before you call either

Deepgram Voice Agent API

  1. Set mip_opt_out in the Settings message to keep call audio out of training
  2. Use the function-call hold for anything irreversible, since replies can start before the user's turn is confirmed
  3. Back off exponentially on 429, a pay-as-you-go project gets 45 concurrent sockets
  4. Pin the LLM version, an unpinned Gemini route failed for 1.5 hours on 21 July 2026
  5. Mint browser tokens with ttl_seconds, not ttl, or they expire after 30 seconds

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

Other comparisons with Deepgram Voice Agent API or Ultravox Realtime API

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