Top Voice & Conversational Interfaces companies
Ranked by total raised · 25 of 44 on the roster · Updated Oct 27, 2026
Together these 25 have raised $170.8B. OpenAI leads with $162.3B, followed by Sierra ($1.6B) and Google ($1.2B).
- #01
OpenAIBuilds frontier large language models including GPT and Codex that power the majority of AI coding tools via API, plus first-party products like ChatGPT and Codex CLI.
Foundation Models · Growth $110B
Foundation ModelsGrowth$110BHQ - #02
SierraSierra builds conversational AI agents for enterprise customer-experience workflows, replacing tier-1 support teams.
Enterprise Voice Agents · Series D $950MEnterprise Voice AgentsSeries D$950MHQ - #03
GoogleGoogle designs its own TPU AI chips, makes Pixel Watch and Fitbit wearables, ships Gemini voice and Veo and Imagen media tools, and co-develops Android XR.
Headsets & Spatial OS · IPO $1.2BHeadsets & Spatial OSIPO$1.2BHQ
- #04
ElevenLabsElevenLabs builds real-time text-to-speech and voice-cloning models with support for 29 languages and ultra-low latency.
TTS / Voice Synthesis · Series D $500MTTS / Voice SynthesisSeries D$500MHQ - #05
ParloaParloa builds no-code conversational AI agents for European enterprise contact centers, specializing in voice and omnichannel automation.
Enterprise Voice Agents · Series D $350M
Enterprise Voice AgentsSeries D$350MHQ - #06
DeepLDeepL provides neural machine translation and launched DeepL Voice in 2024 for real-time speech-to-speech translation.
Speech Translation · Series C $300MSpeech TranslationSeries C$300MHQ - #07
DecagonDecagon builds AI customer-support agents that handle ticket resolution, live chat, and voice calls for mid-market and enterprise SaaS companies.
Enterprise Voice Agents · Series D $250MEnterprise Voice AgentsSeries D$250MHQ - #08
DialpadDialpad provides a cloud business communications platform with built-in voice AI for real-time transcription, sentiment analysis, and agent coaching.
Contact Center AI · Series F $50MContact Center AISeries F$50MHQ - #09
SesameSesame builds fast, high-fidelity voice models for conversational AI with a focus on multilingual support and low-latency inference.
TTS / Voice Synthesis · Series B $250MTTS / Voice SynthesisSeries B$250MHQ - #10
Wispr FlowWispr Flow builds AI voice-dictation software that converts natural speech into formatted text across Mac, Windows, iPhone, and Android, supporting 100+ languages. The company offers both consumer and enterprise deployments with compliance certifications for regulated sectors.
Voice Dictation · Series C $280MVoice DictationSeries C$280MHQ - #11
CrestaCresta provides real-time AI coaching and automation for contact-center agents, analyzing voice and chat to improve sales and support outcomes.
Contact Center AI · Series D $125MContact Center AISeries D$125MHQ - #12
DeepgramDeepgram provides deep-learning-based automatic speech recognition and text-to-speech APIs for real-time transcription and voice synthesis.
STT / ASR · Series C $130MSTT / ASRSeries C$130MHQ - #13
Observe.AIObserve.AI provides voice analytics and agent-assist tools for contact centers, analyzing 100% of calls for compliance and coaching.
Contact Center AI · Series C $125MContact Center AISeries C$125MHQ - #14
CartesiaCartesia develops ultra-low-latency voice models including Sonic, achieving ~40ms time-to-first-audio for real-time conversational AI.
TTS / Voice Synthesis · Series B $100MTTS / Voice SynthesisSeries B$100MHQ - #15
SoundHound AISoundHound AI builds a voice-native conversational AI platform powering in-car assistants, restaurant drive-thru and phone ordering, and enterprise agents through its Amelia platform.
Enterprise Voice Agents · SPAC merger (IPO)Enterprise Voice AgentsSPAC merger (IPO)—HQ - #16
PolyAIPolyAI builds conversational AI for enterprise contact centers, specializing in restaurant reservations, hospitality, and logistics support.
Enterprise Voice Agents · Series D $86M
Enterprise Voice AgentsSeries D$86MHQ - #17
LiveKitLiveKit provides open-source infrastructure for real-time audio and video, powering voice-agent orchestration and WebRTC-based communication.
Voice Agent Infrastructure · Series C $100MVoice Agent InfrastructureSeries C$100MHQ - #18
CognigyCognigy builds enterprise conversational AI for customer service, supporting voice, chat, and omnichannel deployments.
Enterprise Voice Agents · Part of NICEEnterprise Voice AgentsPart ofNICEHQ - #19
Kore.aiKore.ai provides an enterprise conversational AI platform for contact centers, covering voice, chat, and automation across 100+ channels.
Enterprise Voice Agents · Growth $150MEnterprise Voice AgentsGrowth$150MHQ - #20
Inworld AIProvides a character/NPC runtime giving virtual characters personality, memory, and real-time dialogue for games and consumer apps.
Digital Humans & Conversational Avatars · Series A extension $50MDigital Humans & Conversational AvatarsSeries A extension$50MHQ - #21
AssemblyAIAssemblyAI provides AI-powered speech-to-text APIs with sentiment analysis, speaker diarization, and real-time transcription features.
STT / ASR · Series C $50MSTT / ASRSeries C$50MHQ - #22
SanasSanas builds real-time accent conversion technology for contact-center agents, translating non-native accents to standard dialects on live calls.
Accent Conversion · Series B $65MAccent ConversionSeries B$65MHQ - #23
Yellow.aiYellow.ai provides a conversational AI platform for customer service and employee support with voice, chat, and automation features.
Enterprise Voice Agents · Series C $78.2MEnterprise Voice AgentsSeries C$78.2MHQ - #24New
GradiumGradium builds real-time voice AI models for text-to-speech, speech-to-text and live speech translation, which developers and enterprises use through an API to build voice agents and other voice products.
TTS / Voice Synthesis · Seed $100M
TTS / Voice SynthesisSeed$100MHQ - #25
SpeechmaticsSpeechmatics offers automatic speech recognition in 50+ languages with real-time transcription and on-premises deployment options.
STT / ASR · Series B $62MSTT / ASRSeries B$62MHQ