# Citigroup: Technology stack Source: https://www.bankingnewsai.com/banks/citigroup/technology-stack Last updated: Oct 16, 2026 *Part of the [Citigroup AI strategy profile](https://www.bankingnewsai.com/banks/citigroup).* ## What technology stack does Citi use for AI? Citi's AI runs on a stack built during Jane Fraser's transformation, which she said on October 13, 2026 'modernized our core technology platform giving us the foundation we need to implement AI firm wide'. Employees use Citi Assist and Stylus Workspaces, rolled out from late 2024 and running on Google's Gemini and Anthropic's Claude; agentic features were piloted with 5,000 users in September 2025. Arc, launched April 30, 2026, is the platform for building agents that are 'monitored, auditable and governed', and every agent at Citi goes through one central framework built in 2024. Engineers use Citi Squad and GitHub Copilot for coding assistance, and Cognition's Devin, now used by 14,000 engineers, remapped more than 30 years of legacy code; AI code reviews free about 100,000 hours a week. Google Cloud is the main cloud partner under an October 2024 multi-year agreement that includes Vertex AI. Business platforms such as Velocity, Olympus and Stylus in Markets and the Xing risk platform are, per the investor day, foundational to Citi's technology edge, and Services invests over $2 billion a year in platforms including data and AI. Citi retired 548 applications in 2025. ([The Motley Fool (earnings call transcript)](https://www.fool.com/earnings/call-transcripts/2026/10/13/citi-c-q3-2026-earnings-call-transcript/), [Fortune](https://fortune.com/2025/04/09/how-citis-cto-is-rolling-out-new-gen-ai-productivity-tools-to-more-employees-across-the-globe), [The Wall Street Journal](https://www.wsj.com/cio-journal/the-ai-superfans-companies-count-on-to-convert-the-skeptics-5b301a90), [Banking Dive](https://bankingdive.com/news/citi-agentic-AI-tools-stylus-workspaces/760868), [Citigroup](https://www.citigroup.com/global/news/perspectives/2026/introducing-ai-agents-next-phase-citi-artificial-intelligence-journey), [Fortune](https://fortune.com/2026/06/16/brainstorm-tech-agentic-ai-trust-enterprise-dynatrace-citi-ford-experian/), [American Banker](https://www.americanbanker.com/news/citi-is-rolling-out-agentic-ai-to-its-40-000-developers), [Citigroup](https://www.citigroup.com/global/news/perspectives/2026/competitive-differentiator-david-griffiths-building-worlds-most-ai-empowered-financial-institution), [Citigroup](https://citigroup.com/rcs/citigpa/storage/public/investor-day/citi-ID26-full-event-transcript.pdf), [PR Newswire](https://prnewswire.com/news-releases/citi-and-google-cloud-announce-strategic-agreement-to-modernize-citis-technology-infrastructure-and-drive-innovation-302288231.html), [Citigroup](https://citigroup.com/rcs/citigpa/storage/public/investor-day/citi-ID26-discussion-guide.pdf), [Citigroup (SEC filings)](https://www.sec.gov/Archives/edgar/data/831001/000083100126000011/c-20251231.htm)) ## What are the layers of Citi's AI technology stack? | Layer | What Citi uses | Detail | Date | Sources | | --- | --- | --- | --- | --- | | Employee assistants | Citi Assist and Stylus Workspaces | Rolled out to 150,000 staff by April 2025; more than 180,000 people and 87%-plus adoption by September 2026 | 2024-2026 | [Fortune](https://fortune.com/2025/04/09/how-citis-cto-is-rolling-out-new-gen-ai-productivity-tools-to-more-employees-across-the-globe), [Citigroup](https://www.citigroup.com/global/news/perspectives/2026/competitive-differentiator-david-griffiths-building-worlds-most-ai-empowered-financial-institution) | | Models | Google Gemini and Anthropic Claude | Both run inside Stylus Workspaces, per a Citi spokesperson | September 2025 | [Banking Dive](https://bankingdive.com/news/citi-agentic-AI-tools-stylus-workspaces/760868) | | Agent platform | Arc | Developers build agents for well-defined use cases first; 'Every agent will be monitored, auditable and governed' | April 30, 2026 | [Citigroup](https://www.citigroup.com/global/news/perspectives/2026/introducing-ai-agents-next-phase-citi-artificial-intelligence-journey), [CIO Dive](https://www.ciodive.com/news/citi-launches-arc-scale-ai-agents/819113/) | | Agent governance | Central agent framework | One framework, built in 2024, every agent passes through for visibility and traceability | June 2026 | [Fortune](https://fortune.com/2026/06/16/brainstorm-tech-agentic-ai-trust-enterprise-dynatrace-citi-ford-experian/) | | Coding assistants | Citi Squad, GitHub Copilot | Citi Squad to about 9,000 developers by April 2025; 740,000 automated code reviews by July 2025 | 2024-2025 | [Fortune](https://fortune.com/2025/04/09/how-citis-cto-is-rolling-out-new-gen-ai-productivity-tools-to-more-employees-across-the-globe), [American Banker](https://www.americanbanker.com/news/citi-is-rolling-out-agentic-ai-to-its-40-000-developers) | | Coding agents | Cognition Devin | 14,000 engineers; remapped 30-plus years of legacy code; reads only internal repositories, humans approve changes | July 2025-October 2026 | [American Banker](https://www.americanbanker.com/news/citi-is-rolling-out-agentic-ai-to-its-40-000-developers), [Citigroup](https://www.citigroup.com/global/news/perspectives/2026/competitive-differentiator-david-griffiths-building-worlds-most-ai-empowered-financial-institution), [The Motley Fool (earnings call transcript)](https://www.fool.com/earnings/call-transcripts/2026/10/13/citi-c-q3-2026-earnings-call-transcript/) | | Cloud and ML platform | Google Cloud, Vertex AI | Workloads migrating to Google Cloud; Vertex AI for developer toolkits, document processing and servicing | October 2024 | [PR Newswire](https://prnewswire.com/news-releases/citi-and-google-cloud-announce-strategic-agreement-to-modernize-citis-technology-infrastructure-and-drive-innovation-302288231.html) | | Markets platforms | Velocity, Olympus, Stylus, Xing | Foundational to Citi's technology edge; Xing is a scalable risk-management platform | May 2026 | [Citigroup](https://citigroup.com/rcs/citigpa/storage/public/investor-day/citi-ID26-discussion-guide.pdf), [Citigroup](https://citigroup.com/rcs/citigpa/storage/public/investor-day/citi-ID26-full-event-transcript.pdf) | | Legacy retirement | Application decommissioning | 548 applications retired in 2025; AI used to retire old software faster | 2025-2026 | [Citigroup (SEC filings)](https://www.sec.gov/Archives/edgar/data/831001/000083100126000011/c-20251231.htm), [Reuters](https://www.reuters.com/business/finance/citigroup-says-ai-helps-speed-account-openings-systems-upgrades-2026-04-08/) | ## Does Citi build or buy its AI, and how does it control suppliers' AI? Citi builds the employee platforms and the agent layer in house (Stylus, Assist, Arc) and buys models and coding agents from Google, Anthropic and Cognition. Fraser said Devin makes it 'much more efficient for us to do the work in house', insourcing work that cut technology vendor spend by 30% year on year. ([Citigroup](https://www.citigroup.com/global/news/perspectives/2026/competitive-differentiator-david-griffiths-building-worlds-most-ai-empowered-financial-institution), [The Motley Fool (earnings call transcript)](https://www.fool.com/earnings/call-transcripts/2026/10/13/citi-c-q3-2026-earnings-call-transcript/)) Suppliers face tight AI rules. Citi's September 2026 supplier requirements bar vendors and subcontractors from using AI or machine learning, including generative and agentic AI, in products, services or any work that may expose Citi information unless agreed in the contract; breach is material. Suppliers may not use Citi information to train AI without written approval and must help with algorithm audits if a regulator asks. ([Citigroup](https://www.citigroup.com/rcs/citigpa/storage/public/Citi-Requirements-for-Suppliers-English.pdf)) On security, Fraser said Citi deploys frontier models 'securely through a structured harness across our entire perimeter' to find and fix vulnerabilities at speed. Not disclosed: Citi's GPU capacity, its model-hosting split between cloud and own data centers, or a technology budget broken out for AI. ([The Motley Fool (earnings call transcript)](https://www.fool.com/earnings/call-transcripts/2026/10/13/citi-c-q3-2026-earnings-call-transcript/)) ## What does the Citi profile record on this topic? | Date | Move | Detail | Sources | | --- | --- | --- | --- | | Sep 22, 2026 | Group Head of AI profile: 65 million interactions | The bank says Stylus Workspaces has reached more than 180,000 people with 87%-plus adoption, AI cut US client-onboarding document review from about an hour to 15 minutes, and Citi takes part in Anthropic's Project Glasswing. | [Citigroup](https://www.citigroup.com/global/news/perspectives/2026/competitive-differentiator-david-griffiths-building-worlds-most-ai-empowered-financial-institution) | | Jun 16, 2026 | One way to deploy an agent | Markets CIO Nikhil Joshi says every agent at Citi goes through one central framework, built in 2024, for visibility and traceability. | [Fortune](https://fortune.com/2026/06/16/brainstorm-tech-agentic-ai-trust-enterprise-dynatrace-citi-ford-experian/) | | May 1, 2026 | Arc agent platform launched | A platform for building and scaling AI agents, first for developers' internal use cases, then in everyday workflows; 'for the first time, we can deploy embedded AI agents at enterprise scale', said then-CTO David Griffiths. | [CIO Dive](https://www.ciodive.com/news/citi-launches-arc-scale-ai-agents/819113/) | | Sep 22, 2025 | Stylus Workspaces goes agentic | A 5,000-user pilot of agentic AI inside Stylus Workspaces, running on Gemini and Claude models; Griffiths on headcount: 'Does it mean that we need less people? I don't know.' | [Banking Dive](https://bankingdive.com/news/citi-agentic-AI-tools-stylus-workspaces/760868), [The Register](https://theregister.com/2025/09/24/citi_pilots_agentic_ai) | | Sep 9, 2025 | Shobhit Varshney named head of AI | Former IBM head of data and AI named in a memo from COO Anand Selva; he reports to the COO and works alongside CTO David Griffiths. Stylus, Workspaces and Assist had reached 175,000 employees. | [CIO Dive](https://www.ciodive.com/news/citi-AI-head-IBM-Shobhit-Varshney/759949/) | | Jul 14, 2025 | Devin coding agents for 40,000 developers | Citi begins rolling out Cognition's Devin to automate software patches, upgrades and language rewrites; agents work only from internal repositories and humans approve all output. Citi Squad had completed 740,000 automated code reviews, about 100,000 hours a week saved. | [American Banker](https://www.americanbanker.com/news/citi-is-rolling-out-agentic-ai-to-its-40-000-developers) | | Apr 9, 2025 | Assist and Stylus reach 150,000 staff | CTO David Griffiths: Citi Assist and Citi Stylus rolled out to 150,000 employees; Citi Squad, the coding tool, to about 9,000 developers; a new Stylus version goes to 10,000 early adopters, shaped by feedback from AI 'accelerators'. | [Fortune](https://fortune.com/2025/04/09/how-citis-cto-is-rolling-out-new-gen-ai-productivity-tools-to-more-employees-across-the-globe) | | Oct 28, 2024 | Google Cloud multi-year agreement | Citi will migrate workloads to Google Cloud and use the Vertex AI platform for generative AI in developer toolkits, document processing and customer servicing; Tim Ryan: Google Cloud 'opens up a whole new frontier'. | [PR Newswire](https://prnewswire.com/news-releases/citi-and-google-cloud-announce-strategic-agreement-to-modernize-citis-technology-infrastructure-and-drive-innovation-302288231.html) | | Oct 1, 2024 | Citi Stylus Workspaces rolled out | Adoption starts in the single digits; the champions programme is built to change that. | [The Wall Street Journal](https://www.wsj.com/cio-journal/the-ai-superfans-companies-count-on-to-convert-the-skeptics-5b301a90) | ## Common questions ### What is Citi Stylus Workspaces? Stylus Workspaces is Citi's most widely available AI tool for staff, rolled out from late 2024. It runs on Google's Gemini and Anthropic's Claude models, added agentic features in a 5,000-user pilot in September 2025, and had reached more than 180,000 people with over 87% adoption by September 2026. ### What cloud does Citi use for AI? Google Cloud is Citi's main announced cloud partner. A multi-year agreement from October 2024 moves workloads to Google Cloud and supplies the Vertex AI platform for developer toolkits, document processing and customer servicing; Citi Sky is built on Google's Gemini Enterprise Agent Platform. ### How does Citi use AI in software engineering? Citi Squad and GitHub Copilot assist developers, AI code reviews free about 100,000 hours of engineering capacity a week, and Cognition's Devin is the main agentic coding tool, used by 14,000 engineers by October 2026 and credited with remapping more than 30 years of legacy code. ### Can Citi's suppliers use AI? Only with Citi's agreement. The September 2026 Citi Requirements for Suppliers prohibit vendors from using AI or machine learning, including generative and agentic AI, in Citi work or in ways that may expose Citi information unless agreed in the contract, and bar training AI on Citi data without written approval. ## Deeper on Citi - [What is Citigroup's AI strategy?](https://www.bankingnewsai.com/banks/citigroup/ai-strategy) - [What AI patents, partnerships and investments does Citigroup have?](https://www.bankingnewsai.com/banks/citigroup/ai-research-patents-partnerships) - [How does Citi use AI in wealth management, and what is Citi Sky?](https://www.bankingnewsai.com/banks/citigroup/wealth-management-ai) --- Canonical page: https://www.bankingnewsai.com/banks/citigroup/technology-stack Part of [BankingNewsAI](https://www.bankingnewsai.com/) — a free daily brief on AI in banking, an AI regulation tracker (42 authorities, 243 documents) and AI-strategy profiles of the 120 largest US banks. 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