Sierra is an enterprise AI customer service platform co-founded in 2023 by Bret Taylor and Clay Bavor. Taylor is a former Salesforce co-CEO, co-creator of Google Maps, and OpenAI board chair, and Bavor is an 18-year Google veteran who led Google Labs, Lens, and Workspace. Sierra builds conversational AI agents that handle complex, multi-turn customer service interactions autonomously across voice, chat, and digital channels. The agents connect to CRMs, order management systems, subscription platforms, and data warehouses to complete actions rather than only answer questions. As of Q4 2026, Sierra has raised $1B+ in total funding at a $15.8B valuation. It said on October 30, 2026 that it had passed $400M in ARR, adding more than $150M in the third quarter alone, five months after doubling from $100M to $200M took it six. Sierra says it works with almost 50% of the Fortune 50, one in three of the leading banks and five of the ten largest healthcare companies in the world. Half of its customers have revenue exceeding $1B and one in four exceeds $10B. Deployed by ADT, SiriusXM, Sonos, WeightWatchers, Rocket Mortgage, SoFi, Chime, Brex, Ramp, Cigna, Sutter Health, R1 RCM, Redfin, Casper, Nordstrom, Vanguard, Santander and FINRA. Ghostwriter, launched March 25, 2026, lets enterprise teams upload SOPs, call transcripts, whiteboard photos, or audio recordings, or describe a goal in plain English. It then produces a production-ready agent across voice, chat, and email without requiring engineering resources to configure from scratch.
Agent Studio includes 40+ pre-built integrations with third-party knowledge bases, systems of record and contact centers, and since November 2025 its Integration Library lets teams select an integration, add credentials and publish it without code. Custom integrations for proprietary systems are built with Sierra's integration framework or its Agent SDK, agents can reach existing systems through MCP, REST or GraphQL, and the platform connects to data warehouses including Snowflake, Databricks, Google Cloud, Redis and AWS. Channels include voice, chat, email and WhatsApp, in 59 languages. Since October 2025 customers can publish an agent into ChatGPT with one click, exposing that agent to ChatGPT over the Model Context Protocol, with the customer choosing which journeys, data and capabilities are shared. That route is scoped to ChatGPT Apps, and Sierra documents no MCP endpoint for other clients such as Claude or Cursor.
Pricing is outcome-based and fully custom. Sierra charges per resolved outcome rather than per seat or conversation, and publishes no pricing page and no rate card, so all commercial terms are negotiated directly. Sierra publishes no minimum commitment, no platform fee and no per-outcome rate on any public surface. The outcome-based model ties what a buyer pays to resolution volume, and the definition of a resolved outcome and the per-outcome rate are both contract-negotiated terms, so budget modeling requires a commercial discussion.
Sierra is sold to large enterprises and deployment is a sales-led engagement rather than a self-serve signup. Pre-built integrations are configured in Agent Studio without code, while integrations with proprietary systems still take custom engineering work. Published customer timelines run from two weeks to ten weeks to go live. Teams that want a self-serve starting point with published pricing can look at Intercom Fin, which starts at $0.99 per outcome. Teams that want AI layered onto an existing help desk they already run can look at Zendesk AI. Small and mid-sized teams that want a no-code AI agent across web, WhatsApp, Instagram, email and voice can look at Kommunicate.
Current state Q4 2026: Sierra acquired Paris-based Fragment, which helps businesses scale their operations using AI, on April 23, 2026. It closed a $950M Series E at a $15.8B valuation on May 4, 2026, led by Tiger Global and GV, and in August 2026 named Julia Brau Donnelly, formerly CFO of Pinterest, as its Chief Financial Officer. On June 10, 2026 Sierra announced it had been certified FedRAMP High, in partnership with Knox Systems, the standard for cloud companies working with U.S. federal agencies. On September 17, 2026 Sierra announced AIUC-1 certification, a standard written for AI agents, after an independent audit by Schellman and adversarial testing of its chat and voice agents by the Artificial Intelligence Underwriting Company, with that testing repeated at least quarterly. The compliance posture also covers SOC 2 Type II, ISO 27001, ISO 42001, HIPAA, GDPR and CCPA, with CSA STAR Level One self-assessment, PCI DSS 4.0.1 and an EU AI Act listing shown on the trust center. Sierra opened a Toronto office in May 2026 with about a dozen employees. On July 16, 2026 Sierra announced Horizon, a platform for long-horizon agents pursuing multi-step goals such as loan origination, prior authorization or closing a sale over days to months. It layers long-horizon planning and a context engine onto Agent OS. On July 23, 2026 Sierra acquired Takeoff, a long-horizon agent runtime built by a three-person team over 14 months, and the combined teams are building Horizon. In September 2026 Sierra added multimodal agents that bring voice, text and visuals such as product cards, comparison tables, calendars and forms into the same conversation. It also turned Ghostwriter into a teammate inside Slack and Microsoft Teams that can be @-mentioned and raises ideas on its own, rolling out more broadly from early October, and became a launch partner in OpenAI's B2B marketplace, where eligible customers can apply part of their OpenAI commitment to building with Sierra. At its October 2026 Summit Sierra announced two models: Curie, which runs the core orchestration of a conversation, and Fleming, which detects when the caller is another agent. It added Compliance Console to Horizon in late October, with controls such as disclosures and frequency limits by channel, state and country, and on November 2, 2026 it redesigned Agent Studio around Ghostwriter. On November 5, 2026 Sierra announced it had acquired Anon, which helps enterprise AI agents use websites by navigating pages, signing in and filling out forms when there is no API.
