AI
Instinct Quadrupled to $10 Billion in a Month — No App, No User Count
Instinct, a 23-year-old founder's invite-only AI assistant, raised $1B at a $10B valuation — 4x its price from a month earlier, with no app and no public user numbers.
Sierra review
7.6/10★★★★★Enterprise AI agent platform from Bret Taylor and Clay Bavor, sold on outcomes
- Best for
- Large enterprises that want a custom, branded AI agent with white-glove deployment
- Price
- Paid
- Platforms
- Web, API
- Made by
- Sierra
What it is
Sierra builds branded AI agents for large companies that run across chat, voice, SMS, WhatsApp, email and ChatGPT. Its Ghostwriter tool turns SOPs and transcripts into agents, and Monitors, Experiments and Observability track how they perform. Customers include SiriusXM, Wayfair, Vanguard and Redfin.
Latest: Sierra raised $950 million at a valuation above $15 billion in May 2026.
What the AI does
- Ghostwriter agent builder from SOPs and transcripts
- One agent across chat, voice, SMS, WhatsApp and email
- Experiments and multivariate testing
- Monitors and full observability
- Long-horizon planning and proactive outreach (Horizon)
Pros and cons
- Widest channel coverage, including voice
- Strong testing and monitoring tools
- Proven at very large brands
- Extensive compliance certifications (SOC 2, HIPAA, FedRAMP)
- No public pricing; reviews describe enterprise-sized contracts
- Needs significant engineering and deployment effort
- Not built for small teams
How it scores
Top-tier capability and channel reach, held back by opaque pricing and heavy setup.
Feature checklist · 4 of 9
- Free plan or self-serve free trial (no)
- Published, self-serve pricing (no)
- Pay per resolution or outcome (yes)
- Answers phone or voice calls (yes)
- Works across chat, email and messaging apps (e.g. WhatsApp, SMS) (yes)
- Takes actions in other systems (order lookups, refunds, account changes) (no)
- Works on top of an existing helpdesk (e.g. Zendesk, Salesforce) (no)
- Answers in many languages (40+) (no)
- Testing, simulation or AI quality monitoring (yes)
Alternatives
See all Sierra alternatives, ranked →
- Intercom Fin 8.7/10Support teams of any size that want a proven AI agent with transparent per-resolution pricing
- Zendesk AI agents 7.9/10Teams already on Zendesk that want AI agents inside the same helpdesk
- Tidio Lyro 7.6/10Small online stores and businesses that want an AI chatbot running in minutes
- Chatbase 7.6/10Small teams and startups that want a self-serve AI support bot without a helpdesk switch
Intercom Fin vs SierraZendesk AI agents vs SierraSierra vs Tidio Lyro
Sources
▸▸ Sierra in the news
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