agent-builder
(4)
Rowboat
Rowboat (YC S24) is a San Francisco and Bengaluru startup building open-source AI agent software. It began as a pre-trained customer-support LLM agent, grew into a widely starred open-source IDE for building multi-agent systems on the OpenAI Agents SDK, and is now 'your AI coworker, with memory' - a local-first desktop app that turns your emails, meetings, and notes into an editable knowledge graph so agents can actually get work done. Founded by the team behind Agara (acquired by Coinbase in 2021).
Vellum
Vellum is a New York-based AI development platform that helps companies build, evaluate, deploy, and monitor production-grade LLM applications and AI agents. Founded in early 2023 by three engineers who kept hitting the same wall - prototypes that demo well but break in production - Vellum gives teams a workflow builder, an evaluation suite, version-controlled deployments, and live monitoring so they can move AI from proof-of-concept to reliable production systems. The platform works with more than 150 companies including Drata, Redfin, Swisscom, and Headspace, and raised a $20M Series A led by Leaders Fund in July 2025.
StackAI
StackAI is a San Francisco no-code platform for building, deploying, and governing custom AI agents that automate back-office work across enterprise systems like Salesforce, Slack, and Google Workspace. Founded in 2023 by MIT robotics PhDs Antoni 'Toni' Rosinol and Bernardo Aceituno out of Y Combinator's W23 batch, it grew to 100+ enterprise customers and processed over a million documents before Asana acquired it in May 2026 for a reported $75 million to anchor its 'operating system for human-agent teams.'
Wrike
Wrike is an enterprise work management platform that helps teams plan, coordinate, and execute complex projects in one place. Founded in 2006, it combines Gantt charts, Kanban boards, custom workflows, automation, and AI agents to give large organizations visibility and accountability across thousands of users. After passing through several owners - Vista, Citrix, and now Symphony Technology Group - Wrike serves more than two million users across over 18,000 organizations.