OpenAI AgentKit vs Vellum
A side-by-side comparison of capabilities, autonomy, integrations, and pricing to help you choose.
Short answer: choose OpenAI AgentKit if you want openai's toolkit to build, deploy, and optimize agents from prototype to production (Supervised agent, usage); choose Vellum if you want platform to build, evaluate, and deploy llm apps and ai agents (Supervised agent, contact).
| OpenAI AgentKit | Vellum | |
|---|---|---|
| What it is | OpenAI's toolkit to build, deploy, and optimize agents from prototype to production | Platform to build, evaluate, and deploy LLM apps and AI agents |
| Type | platform | platform |
| Autonomy | Supervised agent | Supervised agent |
| Pricing | usage · Free to build; pay standard OpenAI API usage | contact |
| Best for | developers, mid-market, enterprise | developers, enterprise |
| Deployment | api, saas | saas, api |
| Modalities | text, api, code | text, code, api |
| Models | gpt, proprietary | model-agnostic, gpt, claude, gemini |
| Protocols | mcp, function-calling, rest-api | mcp, function-calling, rest-api |
| Integrations | Google Drive, Microsoft SharePoint, Microsoft Teams, Dropbox, OpenAI Agents SDK | Composio, OpenAI, Anthropic, Google Gemini, AWS Bedrock, Cursor |
| Capabilities | 4 documented | 4 documented |
OpenAI AgentKit
- +Lowers the barrier to production agents with a visual builder, embeddable chat UI, connectors, evals, and guardrails in one stack
- +Native to OpenAI's API ecosystem with MCP and prebuilt enterprise connectors, plus code export to the Agents SDK
- +ChatKit and Guardrails are open-source
- -Major lifecycle risk: Agent Builder and Evals are being deprecated (shutdown November 30, 2026) about a year after launch
- -Usage-based pricing makes total cost hard to predict for heavy multi-step agents
Vellum
- +Genuinely model-agnostic with a large, frequently updated catalog, avoiding lock-in
- +Covers the full LLM lifecycle (experiment, evaluate, deploy, monitor) in one place
- +Strong agent tooling with first-class MCP, Composio integrations, and auto-generated function-calling schemas
- -Brand and domain confusion: the apex vellum.ai domain appeared to host an unrelated product at this review
- -Platform pricing is not transparently published (sales-led, enterprise-leaning)
Which should you choose?
OpenAI AgentKit is openai's toolkit to build, deploy, and optimize agents from prototype to production, best for developers, mid-market, enterprise. Vellum is platform to build, evaluate, and deploy llm apps and ai agents, best for developers, enterprise. The right choice depends on the autonomy level you want, your existing integrations, and your budget, all compared above.