Retell AI
Category: AI Agents
Enterprise voice AI agent platform for building, testing, deploying and monitoring AI phone agents for contact centers. Retell AI was founded in 2023. The company is led by Bing Wu. Based in Redwood City, United States. Team size: 11-50. Total funding raised: $4.6M. Latest round: Seed. Key investors include Alt Capital, Y Combinator, Carya Venture, Aaron Levie, Rajat Suri, Siqi Chen, Alex Levin, Michael Seibel, Tyler Bosmeny.
- Founded
- 2023
- Headquarters
- Redwood City, United States
- Team size
- 11-50
- Total funding
- $4.6M
Value proposition
Build, deploy and manage production-grade AI voice agents that answer and make phone calls, take actions in business systems, and scale with call volume, with about 600ms response time.
Products and solutions
Retell voice agent platform (no-code studio, APIs/SDKs), call transfer (cold/warm/2-way warm), IVR navigation, batch calling and Retell Dialer, appointment booking, knowledge base, branded caller ID and verified numbers, post-call analysis, AI QA, Conductor agent builder, persistent contact memory
Unique value
Production-first voice orchestration engine combining deterministic and generative responses, agentic warm transfers, IVR navigation, code execution mid-call, and built-in monitoring, QA and improvement loop, with SOC 2 and HIPAA coverage.
Target customer
Contact centers, BPOs and mid-market to enterprise businesses in healthcare, financial services, insurance, logistics, retail, travel and debt collection.
Industries served
Healthcare, Financial Services, Insurance, Logistics, Retail & Consumer Goods, Travel & Hospitality, Debt Collection, Sports ticketing, Public transit
Technology advantage
Proprietary real-time conversation stack from Retell Labs (denoising, turn-taking, voicemail/IVR detection, reasoning orchestration, Tell-1 model, colloquial rewrite and guardrails) with about 600ms latency. Capital-efficient and profitable, with revenue per employee that is very high.
How they differentiate
Positions as enterprise-grade, production-ready voice AI with low latency, compliance (SOC 2, HIPAA) without add-on fees, bring-your-own-stack flexibility, and a built-in CX improvement loop, versus developer-assembled pipelines (Vapi) and outbound-focused tools (Bland).
Main competitors
Vapi, Bland AI, Synthflow
Key partnerships
OpenAI (collaboration featuring Retell), Twilio, Vonage, Make, n8n, HubSpot, Go High Level, Retell certified solution partner and app partner programs
Notable customers
San Antonio Spurs, Spare (SpareLabs)
Major milestones
Nov 2023 accepted into Y Combinator, Feb 2024 public launch (Hacker News and Product Hunt), Aug 2024 $4.6M seed, Nov 2025 $40M run rate and profitable, Dec 2025 $80M run rate and Brex #4 fastest-growing vendor, Nov 2026 $100M run rate, Tell-1 contact-center model and Retell Dialer launch.
Growth metrics
Annualized revenue run rate crossed $100M (Nov 2026), up from over $3M at the Aug 2024 seed announcement, $40M in Nov 2025 and $80M in Sep 2026; 100M+ connected calls per month; 4,000+ businesses in production; about 25 employees and profitable as of late 2025. A job posting claims a $1.5B+ valuation (unverified).
Market positioning
Positions itself as the leading enterprise voice AI agent platform for high-volume, regulated contact-center operations; ranked #4 fastest-growing software vendor of 2025 by Brex.
Geographic focus
United States / global, with multilingual support for 17+ languages
About Bing Wu
Ex-ByteDance/TikTok Senior Product Manager (B2B products, ~3 years); Co-founder & CEO of Retell AI since Dec 2023; Y Combinator W24.
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Official website: https://www.retellai.com