Decagon vs Sierra in 2026: pricing, products and which one fits

Decagon and Sierra both build AI agents for customer service at large companies, and neither publishes a price. Decagon offers a fixed rate per conversation or a higher rate per resolution, and says most customers choose per conversation (Decagon). Sierra prices by outcomes, paying when the agent achieves an agreed result, with per-conversation pricing for routing interactions (Sierra). Both sell through demos.

This guide compares how each one prices, builds and runs agents, which channels and customers they cover, what their own announcements say about their size, and what smaller teams can use instead. Every fact comes from the vendors’ own websites, checked October 3, 2026. Gleap is not an enterprise AI agent vendor; we cover where it fits at the end.

Decagon vs Sierra at a glance

What Decagon sells

Decagon describes itself as “the AI concierge for every customer” (Decagon). Its homepage names voice, chat and email as channels, and its own comparison page with Sierra adds SMS, WhatsApp, custom surfaces and outbound, in more than 70 languages (Decagon vs Sierra, by Decagon). That page is Decagon’s marketing, so read it as Decagon’s view.

The product pieces Decagon names:

• AOPs, Agent Operating Procedures: workflows for AI agents, defined in natural language instead of a configuration language.
• Watchtower: always-on quality assurance across conversations.
• Insights and reporting, Suggestions and Experiments: analytics, improvement suggestions and testing of agent changes.
• Duet: proposes and self-tests updates to the agent, according to Decagon’s comparison page.
• Decagon Voice: the agent on the phone.

Customers named on Decagon’s homepage include Deutsche Telekom, American Airlines, Delta, Chime, Duolingo, ClassPass, Hunter Douglas, Snapchat and Ticketmaster. Decagon publishes results for some of them, such as a 70% chat and voice resolution rate at Chime and an 80% deflection rate at Duolingo; these are Decagon’s own figures.

What Sierra sells

Sierra builds AI agents on its Agent OS, which it updated to Agent OS 2.0 on November 5, 2025 (Sierra). Its homepage names chat, SMS, WhatsApp, email, voice and ChatGPT as channels, and its product page says agents work in 59 languages.

The product pieces Sierra names:

• Agent Studio, with Journeys: a natural language interface for non-engineers to build production agents, per Sierra’s Agent OS 2.0 post.
• Ghostwriter: an agent that builds agents; you describe how the agent should behave, and it drafts workflows, integrations, guardrails and tone.
• Agent SDK: for engineers who want full control and deep system integrations, at the cost of engineering time.
• Insights: Explorer, Monitors and Experiments to analyze and test agents.

Customers named on Sierra’s homepage include Rocket Mortgage, Gap, Singtel, SoftBank, SiriusXM, Hyatt, Uber, Vanguard, GoFundMe, Santander, Wayfair, Redfin, Rivian, Fanatics and CarMax.

Pricing: per conversation or per outcome

Neither vendor shows a dollar figure. What they publish is the model.

Decagon. In a December 2024 post, Decagon describes two options: a fixed rate per incoming conversation, with volume discounts, or a higher fixed rate per resolution, with no charge for escalations. It says the majority of its customers choose per-conversation pricing (Decagon). As of October 3, 2026, decagon.ai/pricing returned a not-found page.

Sierra. Also in December 2024, Sierra described outcome-based pricing: you pay when the software achieves specific, valuable outcomes agreed with Sierra. For routing or greeter-type interactions, it offers blended or per-conversation consumption pricing (Sierra).

In practice, the difference is who carries the risk. Per-conversation pricing is easier to forecast but charges for conversations the agent hands off. Outcome pricing charges only for agreed outcomes, so the definition of an outcome in your contract matters more than the rate. With either vendor, ask for:

1. The unit price at your volume and how it changes with volume.
2. The exact definition of a billable conversation, resolution or outcome.
3. Minimum commitments, implementation fees and contract length.
4. What happens to the price when the agent’s resolution rate improves.

Company size and funding

Both companies announced large rounds on their own sites:

• Decagon raised a $250 million Series D at a $4.5 billion valuation on January 27, 2026, led by Coatue and Index (Decagon).
• Sierra raised $950 million at a valuation of over $15 billion, announced May 4, 2026 and led by Tiger Global and GV. In the same post, Sierra says it works with over 40% of the Fortune 50 and passed $150 million in annual recurring revenue in February 2026 (Sierra).

Funding does not tell you which agent will work better for your customers, but it does tell you both vendors are investing heavily and are likely to be around for a multi-year contract.

Which one to choose

Consider Decagon if:

1. You want support teams to define agent behavior in natural language through AOPs.
2. You prefer per-conversation pricing that is easy to forecast.
3. Your customers reach you by voice as well as chat and email.

Consider Sierra if:

1. You want outcome-based pricing tied to resolutions or business results.
2. You have developers who will build on an Agent SDK, next to a studio for non-developers.
3. You want agents in ChatGPT as well as your own channels.

Both are enterprise purchases. Run a pilot on real conversations, compare the definitions in each contract and ask each vendor for references in your industry.

Alternatives with published prices

If you are not an enterprise buyer, an AI agent inside a help desk is usually faster to start and has a public price. As of October 3, 2026:

Sources: Intercom pricing, Zendesk pricing, Help Scout pricing. Our list of the best AI help desk software compares ten tools by how they bill AI.

Where Gleap fits

Gleap is AI-native customer support for software teams, not an enterprise agent platform. As of October 2026, Gleap Free costs $0 with one seat and 50 tickets a month, Team costs $149 a month billed annually ($179 monthly) and Pro $299 ($359 monthly), both with unlimited seats, and Enterprise starts at $999.

Team and Pro include five agents. Kai Support answers customers in chat, email and the help center for $0.29 per resolution, charged once per conversation it resolves. Kai Specialist is the second level: it investigates hard tickets with screen recordings, console and network logs, account data and your code, billed by the work it does (about $0.49 per investigation on average), then answers or escalates with a diagnosis. Kai Code opens pull requests your team reviews, Kai PM groups feature requests and Kai Copilot drafts replies. New workspaces get a 7-day free trial, no credit card required.

Decagon and Sierra are built for very large service operations across many channels, including voice, which Gleap does not offer. Gleap fits SaaS and app companies whose hardest tickets are about the product itself. Compare the details on the Decagon alternative and Sierra alternative pages.