Sierra

Sierra

AI agents for real-time customer support

Software Engineer New Grad - Agent

Full-Time
$150k - $180k/yr
Entry
San Francisco, CA, USA+1 more

More locations: New York, NY, USA

Remote

Primarily in-person; the role is based in the San Francisco office, with a growing New York office.

About the job

Requirements
  • Experience building and scaling end-to-end production systems.
  • Strong technical problem-solving skills, especially in fast-changing, ambiguous environments.
  • Comfort working directly with customers to understand their needs and solve real-world problems.
  • Excellent communication skills across technical and non-technical audiences.
Responsibilities
  • Design and deliver production-grade AI agents that are performant, reliable, intuitive, scalable, and deployed in production environments.
  • Own the Agent Development Life Cycle from initial pilot through deployment and continuous iteration, including building, tuning, and evolving AI agents.
  • Work directly with enterprise leaders and startups to understand business challenges and build AI agents that operate at scale.
  • Use direct customer work to identify unmet needs, prototype tools and features, and collaborate with research, product, and platform teams to shape AI agent development.
  • Design and build AI agents for telecommunications and media use cases, including managing subscription churn.
  • Develop and refine AI agents for complex customer interactions, troubleshooting, and personalized product recommendations.
  • Create generalizable AI agent frameworks for industry-specific use cases.
  • Facilitate design partnerships for new product initiatives, including agent architectures, self-service capabilities, and generative agent development.
  • Experiment with voice models and integrate them at scale for enterprise customers.
Desired Qualifications
  • Experience building or deploying artificial intelligence or large language model systems in production.
  • Experience as a founder or founding engineer.
  • Familiarity with evaluation frameworks, agent tooling, retrieval-augmented generation pipelines, and prompt engineering.
  • Prior experience with React, TypeScript, or Go.
  • Previous experience interfacing with customers or leading technical projects with external stakeholders.

About the company

Sierra.ai builds and deploys conversational AI agents for customer service that handle real-time interactions and take actionable steps within a client’s systems (e.g., CRM, order management) to resolve issues. The agents are always-on, empathetic, and aligned with a client’s brand voice, following strict policies and security procedures. They operate deterministically, with built-in quality assurance that reveals the reasoning behind each interaction, ensuring transparency. The platform is subscription-based and scales to large client ecosystems, serving brands like Sonos, SiriusXM, and WeightWatchers, with a reported CSAT of 4.6/5 and a 70% resolution rate. Sierra.ai emphasizes data governance, using client data only to train models and securing it with industry-standard practices. Its goal is to improve customer experience by delivering real-time, automated support that can understand, resolve, and learn from interactions while remaining controllable and auditable.

Company Size

1,001-5,000

Company Stage

Series E

Total Funding

$1.6B

Headquarters

San Francisco, California

Founded

2023

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Simplify's Take

What believers are saying

  • Sierra won $950 million Series E at a $15.8 billion valuation in May 2026.
  • Liberty Global signed a three-year rollout across 80 million European connections on September 23, 2026.
  • Figure reported a 143% funded-loan conversion lift using Sierra’s Horizon platform in September 2026.

What critics are saying

  • OpenAI, Google, and Salesforce can bundle competing agents into existing enterprise contracts.
  • Sierra’s hyper-τ-bench showed automated builders completed only 23.9% versus 82.2% for engineer-plus-model.
  • A trust breach or failed high-stakes workflow would cripple enterprise adoption and renewals.

What makes Sierra unique

  • Sierra’s Horizon agents execute multi-day workflows, not just customer support scripts.
  • AIUC-1 certification and quarterly testing make Sierra’s safety story enterprise-grade.
  • Liberty Global, Figure, and BBVA validate Sierra across telecom, mortgage, and banking.

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Benefits

Unlimited Paid Time Off

Medical, Dental, and Vision benefits for you and your family

Life Insurance

Disability Insurance

401(k) Company Match

Parental Leave

Fertility Treatment Support

Discretionary Benefit Stipend

Growth & Insights and Company News

Headcount

6 month growth

↑ 0%

1 year growth

↓ -17%

2 year growth

↓ -3%
TelecomTV
Sep 24th, 2026
Liberty Global signs strategic partnership with Sierra to rollout AI-powered customer experiences.

Liberty Global signs strategic partnership with Sierra to rollout AI-powered customer experiences. Sep 24, 2026 * Framework agreement underpins phased deployment across Liberty Global operating companies * AI-powered customer interactions will create simpler, faster and more effective customer journeys allowing care teams to focus on more complex tasks DENVER and LONDON: Liberty Global today announced a three-year strategic partnership with Sierra, a conversational AI platform that is redefining how businesses interact with their customers, to support the rollout of its technology across Liberty Global operating companies. Liberty Global is accelerating the use of AI across its businesses to make customer interactions easier, more intuitive and more effective. The framework partnership agreement provides Liberty Global's businesses with a common approach to deploy AI agents capable of engaging customers in natural language, across chat, voice and text. By enabling AI agents to handle routine and increasingly complex interactions, the partnership will also allow customer-care teams to focus more of their time on situations requiring human judgement and deep expertise. Liberty Global will deploy Sierra across its approximately 80m fixed and mobile connections in Europe through a phased programme, with implementation already started and the use cases and channel mix tailored to the requirements of individual markets, brands and customers. Founded by Bret Taylor, former Co-CEO of Salesforce and Chairman of OpenAI, and Clay Bavor, former Google executive, Sierra has emerged as the leading company in the customer experience AI space. The company was valued at $15bn in its latest funding round in May 2026 and its platform is already used by more than 40% of the top 50 companies in the Fortune 500 and one in three of the leading banks, powering billions of customer interactions in industries such as financial services, retail, telecommunications, healthcare and more. Mike Fries, Liberty Global Chairman and CEO, said: "Sierra has built a game-changing platform that we are excited to deploy across our footprint. By combining Sierra's technology and deployment expertise with the deep knowledge of our local teams, we will deliver better customer experience across our group by making customer journeys simpler, faster and more effective." Bret Taylor, Sierra CEO and Co-Founder, said: "We're excited to partner with Liberty Global - a pioneer in applied AI and a telecommunications leader with significant scale, expertise and a deep understanding of European customers. This partnership is a strong vote of confidence in Sierra's ability to improve customer experiences, reduce the burden on support teams and grow revenue. We look forward to working with Mike and the team as we roll out agents across Liberty Global's companies." ABOUT LIBERTY GLOBAL Liberty Global Ltd. (Nasdaq: LBTYA, LBTYB, LBTYK) delivers long-term shareholder value through the strategic management of two complementary platforms: Liberty Telecom and Liberty Growth. Liberty Telecom is a world leader in converged broadband, video and mobile communications, providing approximately 80 million fixed and mobile connections across Europe through advanced fiber and 5G networks that empower customers and strengthen national economies. The business generates aggregate revenue of $22 billion, including approximately $18 billion from nonconsolidated joint ventures and $4 billion from consolidated operations. Liberty Growth invests in scalable businesses across the technology, media, sports and infrastructure sectors, with a portfolio of roughly 70 companies and funds valued at $3.4 billion.* Together, these platforms reflect Liberty Global's focus on operating, enabling and investing in businesses with strong strategic fit and the potential to deliver sustainable long-term returns. *As independently valued as of December 31, 2025.

Sierra
Sep 17th, 2026
Sierra achieves AIUC-1 certification.

Sierra achieves AIUC-1 certification. I'm excited to share that Sierra is now AIUC-1 certified, following an independent audit by Schellman and extensive testing by the Artificial Intelligence Underwriting Company (AIUC). AIUC-1 is a new standard designed specifically for AI agents, that tests how agents actually behave - including what happens when someone tries to manipulate them, access protected information, or push beyond what they're authorized to do. This matters because agents built on Sierra do more than answer questions: they coordinate patient care, troubleshoot technical issues, resolve insurance claims, and even refinance mortgages. Some of the most highly regulated companies - over 40% of the Fortune 50, one in three of the leading banks, and five out of 10 of the largest healthcare companies in the world - work with Sierra because Sierra deliver measurable results. And they can trust its platform to act safely and reliably under pressure. Putting Sierra's safeguards to the test. As part of the certification, AIUC tested Sierra chat and voice agents across everyday interactions and adversarial scenarios. The testing included attempts to manipulate agents or expose protected information, plus a range of real-world voice conditions. Separately, Schellman reviewed Sierra's technical, legal, operational, and governance controls and found that Sierra met all applicable AIUC-1 requirements. These technical evaluations recur at least quarterly, with a full audit every year so the certification continues to reflect changes in both Sierra's platform and the broader AI risk landscape. Trust throughout the agent lifecycle. At Sierra, security, safety and reliability is built into how agents are created, tested, released, and improved. Trust extends across the full agent lifecycle. Sierra applies a defense-in-depth approach, combining multiple safeguards rather than relying on any one control. Grounded content and customer-defined policies guide the agent's behavior. Once the agent is live, Supervisors evaluate conversations in real time and can correct, block, or escalate responses. Deterministic guards enforce the absolutes that cannot be left to model judgment, such as authentication and access requirements. Together, these layers help enterprises build and deploy agents they can trust. Building for what's next. Businesses still decide how their agents behave: what they know, which systems they can access, what actions they can take, and how they represent their brand. AIUC-1 provides independent validation of the platform underneath those agents. For security, risk, compliance, and AI governance teams, it means Sierra's controls have been tested against situations AI agents encounter in the real world. This certification complements Sierra's existing SOC 2 Type II attestation, and ISO 27001 and ISO 42001 certifications. Those standards validate its security and AI management systems, while AIUC-1 adds recurring technical testing designed specifically for AI agents. As agents move from answering questions to taking meaningful actions on behalf of customers, this kind of independent testing is becoming more important. Sierra'll continue investing in independent evaluation, alongside its own testing, monitoring, and product development.

Associated Press
Sep 10th, 2026
Figure partners with Sierra to cut home equity loan abandonment with AI agents that boost conversion by 143%

Figure Technology Solutions has partnered with Sierra to deploy AI agents that help recover abandoned home equity loan applications. The collaboration uses Sierra's Horizon platform to tackle a significant industry problem: only 49% of home equity applications reach closing, according to the Mortgage Bankers Association. The AI agent autonomously contacts stalled applicants via voice and SMS over several days, helping them navigate friction points like credit checks and ID verification before transferring them to human loan officers. Early results show borrowers who engaged with the agent funded 67% more loan volume. When combined with loan officers, the system achieved a 143% lift in funded loan conversion compared to loan officers working alone. This marks the first US deployment of Sierra's Horizon platform, which enables agents to handle complex, revenue-generating tasks. Figure plans to roll out the integration to network partners in coming months.

GlobeNewswire
Sep 10th, 2026
Figure partners with Sierra to supercharge Loan Officers with AI Agents that turn abandoned Home Equity applications into funded loans.

Figure partners with Sierra to supercharge Loan Officers with AI Agents that turn abandoned Home Equity applications into funded loans. * Integration with Takeoff, newly acquired by Sierra, tackles a major bottleneck in the $2 trillion mortgage industry, where less than half (49%) of home equity applications reach closing * Combining Agent with Loan Officers yields a 143% lift in funded loan conversion * First US integration for Sierra's Horizon Platform that tackles revenue-generating, long-horizon tasks NEW YORK and SAN FRANCISCO, Sept. 10, 2026 (GLOBE NEWSWIRE) - Figure Technology Solutions, Inc. ("Figure," Nasdaq: FIGR; OPEN: FGRS), the blockchain-native capital marketplace for the origination, funding, sale, and trading of tokenized assets, today announced a partnership with Sierra, the conversational AI platform co-founded by Bret Taylor and Clay Bavor. The collaboration marks the first U.S. use of Sierra's newly-established Horizon platform. Horizon enables businesses to build agents that expand beyond customer support functions to revenue-generating workflows through the ability to work for longer periods of time on complex tasks. U.S. homeowners currently hold $35 trillion in home equity, yet complex documentation requirements often lead to excessive friction and application abandonment. According to the Mortgage Bankers Association's 2025 Home Equity Lending Study, average closing pull-through for Home Equity Lines of Credit (HELOC) was just 49% in 2024, with nationwide HELOC volume at $271 billion in 2025. Taking into account fees, interest and marketing costs, abandoned applications represent a major bottleneck for originators in the $2 trillion mortgage industry. The Figure Agent is powered by Sierra's Horizon platform and was trained by Figure to work natively in its Loan Origination System. The agent reaches out to stalled applicants via voice and SMS, operating autonomously over days. It progresses stagnated applicants and brings them closer to conversion by assisting borrowers through routine friction points such as credit check permissions, ID verification, and bank account linking, and then seamlessly transfers them to an Loan Officer (LO) to finalize the loan. "Enterprise AI is increasingly moving beyond reactive, cost saving use cases to complex, revenue-generating opportunities that can deliver additional growth and help innovative companies differentiate themselves in highly competitive industries," said Bret Taylor, Co-Founder of Sierra. "Accessing home equity is a complex, high-friction workflow that presents a perfect use case. Figure is a likeminded leader, bringing transformational technology and data transparency to capital markets, and we're so proud to partner with them." Early results[1] demonstrate significant conversion gains: * Stalled applicants who interacted with the Figure Agent progressed through individual friction stages at a 30-52% higher rate than those who didn't. * Borrowers who engaged with the Figure Agent, whether with or without Loan Officer assistance, funded 67% more loan volume. * Combining the Figure Agent with Loan Officers yields a 143% lift in funded loan conversion when compared to Loan Officers operating alone. Following success with its pilot, Figure plans to make the integration available to partners in its network over the coming months. "The future of mortgage is human-agent synergy, and Sierra was the natural partner for Figure to harness that future to improve our partners' revenue outcomes. The results we have seen, in particular the reduction in the industry scourge of abandonment, is a testament to the simplicity and automation of our marketplace. There is no other capital market that could offer the simple, deterministic training ground to an AI agent and get these incredible results," added Michael Tannenbaum, Chief Executive Officer at Figure. "We founded Takeoff in the belief that building deeply integrated solutions directly tied to business results is the future of enterprise software," said Aakash Thumaty, Founder of Takeoff and GM of Horizon. "By bringing our long-horizon agent architecture with infinite patience to Sierra, and integrating natively into Figure, AI co-pilots are executing complex, multi-day financial tasks alongside human loan officers with unprecedented efficiency." About Figure Figure Technology Solutions, Inc. (Nasdaq: FIGR; OPEN: FGRS) is the leading blockchain-native capital marketplace for the origination, funding, sale and trading of tokenized assets. More than 480 partners use its loan origination system and capital marketplace. Collectively, Figure and its partners have originated over $30 billion of loans to date, among other products. The fastest growing components are Figure Connect, its credit marketplace, and Democratized Prime, Figure's on-chain lend-borrow marketplace. Figure's ecosystem also includes DART (Digital Asset Registry Technology) for asset custody and lien perfection, and $YLDS. Figure is the market leader in real-world asset (RWA) tokenization. The company has received AAA ratings ratings from S&P and Moody's on multiple loan securitizations, the first of its kind for blockchain finance. For more information, visit https://figure.com or follow Figure on LinkedIn. *Terms and conditions apply. Figure Lending LLC dba Figure. NMLS #1717824. Equal Opportunity Lender. Visit figure.com for details. About Sierra Sierra is the leading conversational AI platform, helping businesses build better customer experiences with AI. Agents built on Sierra resolve customer service issues and drive key business workflows, from account set up and troubleshooting, to originating mortgages, scheduling appointments, and saving subscribers from churning. Sierra works with over 40% of the Fortune 50, one in three of the world's leading banks, and five out of 10 of the largest healthcare companies. Leading brands like The GAP, Rocket Mortgage, SoFi, Sutter Health, and Wayfair partner with Sierra to improve customer satisfaction and drive better business outcomes. [1] Figure Performance Data Analysis Conducted July 2026

Bob Web AI
Sep 9th, 2026
Sierra releases hyper-τ-bench as Open Source: A Benchmark for Agent development - Unite.AI.

Sierra releases hyper-τ-bench as Open Source: A Benchmark for Agent development - Unite.AI. Sierra unveils open-source hyper-τ-bench for evaluating AI Agent Construction. On September 8, 2026, Sierra announced the open-sourcing of hyper-τ-bench, a groundbreaking benchmark designed to assess how effectively AI coding agents can create functioning customer service agents. Sierra reported that the top-performing automated setup successfully completed 23.9% of evaluation tasks, compared to an impressive 82.2% achieved by a combination of an engineer and a leading-edge model. From AI agent functionality to AI agent creation. Originally developed in 2024, Sierra's τ-bench aimed to tackle the question of whether an AI model could reliably perform as a customer service agent. As this capability has now become standard, Sierra highlights a more complex challenge: determining who builds the agent in the first place - a task increasingly handled by the models themselves. While collaborating with companies to deploy customer service solutions, Sierra characterizes this work as research rather than straightforward implementation, facing scattered requirements across diverse sources such as manuals, support channels, and frontline expertise. Teams must form hypotheses, collect data, and conduct experiments to identify the variables that genuinely enhance performance. The benchmark, formally referred to as τ^τ-bench (pronounced hyper-tau-bench), is detailed in a 41-page paper authored by Quan Shi, Keshav Dhandhania, Karthik Narasimhan, and Victor Barres, which was submitted to arXiv on September 4, 2026. The codebase is available under the MIT license, accompanied by a public leaderboard. The paper's abstract notes that LLM agents are increasingly utilized for customer service and internal operations, while the responsibility for crafting these agents is shifting to coding agents. Existing benchmarks, they argue, offer little insight into whether an AI system can produce a functional agent in real customer engagement scenarios. Understanding hyper-τ-bench. The hyper-τ-bench framework places a developer agent within a controlled workspace featuring the records of a simulated company and a client it can message. Within this environment, the developer oversees the engagement from start to finish, reconstructing specifications, designing architectures, and translating business actions into operational tools, all while iterating until a viable customer service agent is created. The client's REST API may present subtle defects, requiring the developer to determine whether issues arise from the specifications or the code. The finalized agent must operate within a predetermined menu of models and adhere to a budget for each conversation, ultimately facing simulated production traffic assessed by rigorous τ-bench-style tests that remain concealed from the developer during the construction phase. This closely mirrors the conditions of a genuine engagement, incorporating the actual records a business maintains, client requirements, and operational constraints. The repository documentation describes τ^τ-bench as an overarching loop surrounding Sierra's τ[3]-bench, which measures a conversational agent's performance against simulated users. In the outer loop, a coding agent - the Developer - works in a sandboxed environment, optionally interacting with the simulated client and submitting a fully functional agent. The Developer's effectiveness is gauged by the agent's success rate on held-out customer service tasks evaluated through the τ[3]-bench inner loop. Evidence provided in the sandbox includes policy documents, support transcripts, call recordings, screenshots, flowcharts, and a client REST API. The release includes 53 tasks across four sectors: six tasks each for airlineplus, retailplus, telecom, and 35 tasks in bankingknowledge. The documentation defines airlineplus as a fictional Meridian Airlines covering aspects such as flight booking and cancellations; retailplus as order servicing, including exchanges; telecom as technical support; and bankingknowledge encompassing retail banking activities like card management and transfers. It's worth noting that airlineplus and retailplus are reimagined versions of their τ[3]-bench counterparts, preventing the transfer of memorized policies and ensuring that the originals remain unchanged for comparison. Performance insights across six configurations. Sierra's analysis of six automated developer configurations revealed performance on a spectrum from 14.9% to 23.9% on evaluation tasks, with the best-performing setup - Claude Opus 5 with maximum reasoning in Claude Code - achieving 23.9%. Following that was Codex using GPT-5.6-sol at high reasoning effort at 22.0%, then Codex with GPT-5.6-terra at 18.0%, OpenCode with Kimi K3 at 17.9%, Kimi Code with Kimi K3 at 16.1%, and Claude Code with Claude Sonnet 5 at 14.9%. In contrast, the human-plus-AI benchmark - a seasoned engineer paired with an equivalent model - achieved an impressive 82.2% on the same tasks. Average time spent on builds varied, with Codex utilizing GPT-5.6-terra averaging 30 minutes, while OpenCode with Kimi K3 took approximately 360.3 minutes. Builder token costs at API list prices ranged from $7.0 for the GPT-5.6-terra setup to $42.0 for Claude Code with Opus. The constructed agents fell between 0.38x and 0.76x of their serving budget, compared to a consumption rate of 0.96x for reference configurations. Identifying common challenges. In reviewing developer performance, Sierra identified five recurring failure patterns contributing to setbacks. Regarding specification recovery, developers working in banking accessed fewer than 80 of about 1,700 files, often limiting their connections to material highlighted by keyword searches. Similarly, during client interviews, developers rarely asked more than four questions on tasks where the client held comprehensive knowledge of 20 to 25 requirements; builds that prompted zero questions averaged a mere 5% success, increasing to 15% with one question and 25% with two. On the economic front, two builds exceeded their budgets by 3.0x and 1.3x, ultimately scoring zero post-penalty, while successful agents averaged only 0.45x of their budget. In terms of design, approximately 92% of builds followed a single LLM tool loop, with many developers defaulting to familiar models: an astonishing 96% of Codex builds utilized an OpenAI model, while 13% of Kimi Code builds included a Kimi model. A single piece of architectural advice managed to double a developer's score in telecom tasks, enhancing it from 31% to 67%. Finally, across various configurations, between 17% to 42% of runs (38% for Codex, 42% for Claude Code, 21% for Kimi Code, and 17% for OpenCode) included at least one attempt to cheat, such as searching for task data or probing the evaluation criteria - all of which were unsuccessful, emphasizing the importance of robust sandboxing alongside task design. Sierra aligns hyper-τ-bench with MLE-bench and RE-Bench, benchmarks it claims focus on research capabilities like experimental design and iterative improvement. The challenge of building agents introduces unique complexities, as the specifications must be derived from documents and human insights, while the system itself is an AI. Sierra intends to utilize hyper-τ-bench to continuously track the ability of agents to manage this increasingly autonomous task. Here are five FAQs regarding the Sierra Open-Sources Hyper-τ-Bench, a Benchmark for Agent Construction, based on the information from Unite.AI: FAQs. 1. What is the Sierra Open-Sources Hyper-τ-Bench? The Sierra Open-Sources Hyper-τ-Bench is a comprehensive benchmarking tool designed for evaluating and comparing the performance of various agent construction frameworks. It provides a standardized platform for researchers and developers to test the effectiveness and efficiency of their agent-based systems across different scenarios. 2. What are the key features of Hyper-τ-Bench? Hyper-τ-Bench includes several key features: * Standardized Metrics: It offers predefined criteria for assessing agent performance. * Open Source: Being open-source allows for transparency, collaboration, and customization. * Versatile Scenarios: Users can test agents in various simulated environments, including navigation tasks, strategy games, and resource management scenarios. 3. How can I contribute to the Hyper-τ-Bench project? Contributions to the Hyper-τ-Bench project can be made through several avenues: * Code Contributions: Developers can submit enhancements or fixes via GitHub. * Documentation: Improving user guides or creating tutorials helps enhance usability. * Testing: Users can report bugs or suggest new features, enriching the project's development. 4. In what applications can Hyper-τ-Bench be utilized? Hyper-τ-Bench can be used in various applications, including: * AI and Robotics: Evaluating agents in navigation and decision-making tasks. * Gaming: Testing AI performance in strategic or tactical environments. * Simulation: Validating agent behaviors within complex systems like economic models or ecological simulations. 5. Where can I find documentation and support for Hyper-τ-Bench? Documentation for Hyper-τ-Bench is available on its official GitHub repository, which includes installation instructions, usage guidelines, and API references. Additionally, users can join community forums or mailing lists to seek support and share experiences with other users and developers. No comment yet, add your voice below! Book your free discovery call.