Vellum
Developer platform for production-ready LLM applications.
RIP Vellum
Shut down · November 2026
Vellum began as a developer platform for building and testing LLM applications, then pivoted in 2026 to a personal AI assistant. It shut that platform down on November 2, 2026, citing fierce competition and weak distribution: cloud-hosted assistants stopped working, logins closed and user data was deleted. The open-source assistant harness lives on as Cadet, a fork maintained by Vellum's founding engineer.
Is Vellum shut down?
Yes. Vellum shut down on November 2, 2026 and is no longer available. Its record is preserved in the ToolDirectory.AI graveyard, our hand-reviewed registry of AI tools that shut down or were acquired.
What to use instead
Overview
Vellum: The Ultimate Developer Platform for LLM Applications
Vellum is a robust developer platform designed to facilitate the transition of LLM-powered features from prototype to production. It offers a suite of tools that cater to prompt engineering, semantic search, version control, quantitative testing, and performance monitoring. Compatible with all major LLM providers, Vellum ensures that developers can confidently move from prototyping to deploying their applications.
Shutdown note (November 2026): Vellum shut down its Personal Assistant platform on November 2, 2026. Cloud-hosted assistants stopped working, logins to vellum.ai closed and user data was deleted. Self-hosted assistants keep working, and Vellum's founding engineer maintains an open-source fork called Cadet.
Key Features:
- Rapid Experimentation: Eliminate the need for multiple browser tabs and spreadsheet tracking.
- Regression Testing: Validate changes against a bank of test cases and recent requests.
- Contextual Prompts: Dynamically include company-specific context in prompts.
- Version Control: Track and manage prompt changes without altering the code.
- Observability & Monitoring: Gain insights into model interactions, quality, latency, and cost.
- Provider Agnostic: Flexibility to choose the best LLM provider for specific needs.
Ideal Use Case:
Vellum is ideal for developers, AI enthusiasts, and businesses aiming to integrate LLM-powered features into their applications. It simplifies the process of prompt engineering and ensures that applications remain up-to-date and efficient.
Why use Vellum:
- Efficient Prototyping: Quickly develop MVPs by experimenting with various prompts and parameters.
- Reliable Proxy: Acts as a low-latency, reliable proxy to LLM providers.
- Data Collection: Gathers model inputs, outputs, and user feedback for future improvements.
- Provider Flexibility: Avoid being tied to a single LLM provider.
tl;dr:
Vellum provides a comprehensive platform for developers to seamlessly integrate LLM-powered features into their applications. With tools for prompt engineering, testing, and monitoring, it ensures optimal performance and user satisfaction.
FAQ
Is Vellum shutting down? Yes. Vellum shut down its hosted platform on November 2, 2026. Only self-hosted copies of its open-source assistant, continued as the Cadet fork, still run.
Q: What is Vellum? A: Developer platform for production-ready LLM applications.
Q: How is Vellum priced? A: Vellum offers a free trial. See the Vellum pricing page for current tier details.
Q: What problem does Vellum solve? A: Vellum helps developers and engineering teams ship code faster with AI-powered coding, debugging, and review tools.
Q: What can replace Vellum? A: Top alternatives to Vellum include GitHub Copilot, Cursor, and v0. Explore alternatives in the same category for more options.
Related
Looking for more options? Browse the Developer Tools directory or read our best AI coding tools listicle. Vellum is also tracked on Crunchbase.
Why Use Vellum
