Decagon vs Sierra AI (2026)
Decagon and Sierra are the two names that come up when a well-funded team wants best-in-class autonomous agents and money is not the first question. Both launched in 2023, both bill on outcomes, and both take weeks of white-glove onboarding. The choice tends to hinge on which reference customers look most like you and which platform's guardrails you trust on your own queue.
At a glance
| Attribute |
 Decagon
|
 Sierra AI
|
|---|---|---|
| What it is | Hire our generative AI agents to give customers a mind-blowing experience. Trusted by massive enterprises and high-growth startups. | AI agent mirrors the nuances of human communication, ensuring seamless and organic customer service interactions while improving customer satisfaction. |
| Pricing | Per resolution · Custom | Per resolution · Custom |
| Est. monthly cost | No published price to estimate | No published price to estimate |
| Founded | 2023 | 2023 |
| Categories | AI Agents & Chatbots Enterprise | AI Agents & Chatbots Enterprise Voice & Phone AI |
| Channels | ||
| Chat | ✓ | ✓ |
| ✓ | ✓ | |
| Voice | ✓ | ✓ |
| SMS | — | ✓ |
| — | ✓ | |
| Compliance (vendor-claimed) | ||
| SOC 2 | ✓ | ✓ |
| HIPAA | ✓ | ✓ |
| GDPR | — | ✓ |
| ISO 27001 | — | ✓ |
| PCI DSS | ✓ | ✓ |
| FedRAMP | — | ✓ |
| ISO 42001 | — | ✓ |
| EU AI Act | ✓ | ✓ |
| Data residency | Not verified | Not verified |
| Languages | 70+ languages | 59 languages |
| What the AI can do | ||
| Takes actions | ✓ | ✓ |
| Hands off to a human | Not verified | ✓ |
| Choice of LLM | Not verified | Not verified |
| Buying | ||
| Free trial | Not verified | Not verified |
| How you buy | Not verified | Not verified |
| Minimum commitment | — | — |
| Company | Independent, venture-backed | Independent, venture-backed |
| Works with | Zendesk Salesforce Intercom Shopify Stripe Kustomer | Salesforce Zendesk Shopify Twilio Stripe Snowflake |
| Key features |
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| Next step |
Full listing Visit site → |
Full listing Visit site → |
Estimates assume 5,000 conversations a month, 60% handled by AI and 10 agent seats, at each vendor's published list price (the cost calculator's model); treat them as a floor, not a quote. Compliance rows are what vendors publicly claim, and “Not verified” means we have not confirmed that fact yet, not that the tool lacks it.
Choose Decagon or Sierra AI?
Choose Decagon if
Best for: High-growth and enterprise consumer companies that want a concierge-grade AI agent across chat, email and voice, with refunds and billing changes executed through Zendesk, Salesforce, Stripe or Shopify, usage-based pricing with no seat fees, and HIPAA, PCI DSS and EU AI Act coverage.
- you prefer its particular feature set and integrations
Look elsewhere if you want published prices, a free trial or a self-serve start: Decagon is white-glove and quote-based, and its verified facts do not include a stated data residency.
Choose Sierra AI if
Best for: Large brands that want one branded agent deployed across chat, voice, email, SMS and WhatsApp, with voice agents that can take a payment mid-call, outcome-based pricing, 59 languages and the broadest compliance list in the directory including FedRAMP, ISO 42001 and the EU AI Act.
- you need voice and phone AI
- you need SMS and WhatsApp coverage
- you need a vendor that publicly claims GDPR, ISO 27001, and FedRAMP
Look elsewhere if you are not an enterprise: Sierra sells multi-year contracts by quote with no trial or self-serve start, and its verified facts do not include a stated data residency.
About Decagon
Decagon builds what it calls an AI concierge: autonomous agents that resolve customer issues across chat, email, voice, and SMS, all sharing one brain and one memory of your customer. Instead of trapping your logic in brittle decision trees, Decagon uses Agent Operating Procedures, plain-language playbooks that describe how you want issues handled. Its voice agents answer with sub-second latency, handle interruptions gracefully, and can dial out as well as pick up, which makes them feel far closer to a competent human than to a phone tree.
The company's rise has been ridiculous in the best possible way. Founded in 2023 by Jesse Zhang and Ashwin Sreenivas, alumni of Google, Palantir, Citadel, and Scale AI, Decagon went from a standing start to a multi-billion-dollar valuation in roughly two and a half years, with its worth reportedly tripling in a single seven-month stretch as investors piled in. The name itself is a quiet math joke, nodding to the ten-sided polygon.
What keeps the logos coming is deployment quality. Decagon leans into white-glove onboarding, exposes full conversation logs so teams can audit and improve every answer, and routes genuinely hard cases to humans cleanly rather than bluffing. Its customer roster reads like a tour of the modern internet: Notion, Duolingo, Rippling, Eventbrite, Substack, Chime, and Affirm among them, plus larger enterprises adopting its outbound and proactive agents.
Pricing is sales-led and usage-based, offered per conversation or per resolution with volume discounts, so it is squarely an enterprise purchase rather than a quick self-serve signup you try on a whim. For teams that want an AI agent that feels concierge-grade, keeps a persistent memory of each customer, and can be tuned in the plain language a support manager actually speaks day to day, Decagon has become one of the most talked-about names in the category.
Read the full Decagon listing → · See Decagon alternatives →
About Sierra AI
Sierra builds conversational AI agents for the enterprise, and it arrived with about as much star power as a startup can carry. It was founded in 2023 by Bret Taylor and Clay Bavor, and if those names ring a bell it is because Taylor co-created Google Maps, served as CTO of Facebook and co-CEO of Salesforce, and currently chairs the board of OpenAI, while Bavor spent eighteen years at Google leading its virtual and augmented reality work. Company lore says the whole thing was hatched over a grilled branzino lunch in Palo Alto.
The product lives up to the pedigree. From a single build, Sierra deploys a branded agent across chat, voice, email, SMS, and even ChatGPT, following your policies, adopting your brand's voice, and escalating gracefully when a conversation gets thorny. Its voice agents are a standout: they hold natural, low-latency conversations, read sentiment, and can even take a credit card or ACH payment over the phone in one uninterrupted call, with no clumsy handoff to a separate system.
Under the hood sits Agent OS, a platform for building, testing, and supervising agents, with tooling to run voice simulations and rehearse behavior before anything reaches a real customer. Pricing is outcome-based, tied to conversations or successful resolutions and wrapped in multi-year enterprise contracts, so Sierra is aimed at large brands rather than weekend experimenters. Reported customers include SoFi, Ramp, and Brex, and the company says its agents already serve a meaningful slice of the Fortune 50.
Sierra's fundraising has kept pace with its towering ambition, vaulting the company into the rarefied tier of the most valuable AI startups in barely two years. For enterprises that want polished, on-brand agents across every channel and are willing to invest the time and budget to do it properly, Sierra is a genuine marquee choice.
Read the full Sierra AI listing → · See Sierra AI alternatives →
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