OpenAI Agents SDK vs Vellum AI: Which is Better in 2026?
Choosing between OpenAI Agents SDK and Vellum AI comes down to understanding what each tool does best. This comparison breaks down the key differences so you can make an informed decision based on your specific needs, not marketing claims.
Bottom line: OpenAI Agents SDK is our overall pick for AI assistants workflows. Pick Vellum AI if you need AI agents.
Short on time? Here's the quick answer
We've tested both tools. Here's who should pick what:
OpenAI Agents SDK
A lightweight, powerful Python framework for building multi-agent AI workflows.
Best for you if:
- • You need something completely free
- • You need AI assistants features specifically
- • Build multi-agent AI workflows with LLMs.
- • Provider-agnostic, supporting OpenAI and 100+ other LLMs.
Vellum AI
Build, debug, and deploy AI agents and workflows with a no-code builder or SDK.
Best for you if:
- • You need AI agents features specifically
- • Build and deploy AI agents and workflows using no-code or SDK.
- • Debug and iterate on AI systems with visual graphs and advanced control flow.
| At a Glance |  OpenAI Agents SDK |  Vellum AI |
|---|---|---|
Starts at | FreeFree tier available | FreeFree tier available |
Best For | AI Assistants | AI Agents |
Rating | - | - |
Choose OpenAI Agents SDK or Vellum AI?
Choose OpenAI Agents SDK if
A lightweight, powerful Python framework for building multi-agent AI workflows.
- Highly flexible due to provider-agnostic LLM support.
- Simplifies complex multi-agent system development with core concepts.
- Enhances reliability with guardrails and human-in-the-loop features.
- You want a fully free tool (Vellum AI requires payment)
- Your work is AI assistants-shaped, not AI agents-shaped
Choose Vellum AI if
Build, debug, and deploy AI agents and workflows with a no-code builder or SDK.
- Accelerates AI development timelines significantly
- Facilitates collaboration between technical and non-technical teams
- Provides robust debugging and iteration capabilities
- Your work is AI agents-shaped, not AI assistants-shaped
| Feature | OpenAI Agents SDK | Vellum AI |
|---|---|---|
| Pricing Model | Free | Freemium |
| User Rating | No ratings yet | No ratings yet |
| Categories | AI AssistantsDeveloper Tools | AI AgentsWorkflow Automation |
In-Depth Analysis
OpenAI Agents SDK
A lightweight, powerful Python framework for building multi-agent AI workflows.
Strengths
- +Highly flexible due to provider-agnostic LLM support.
- +Simplifies complex multi-agent system development with core concepts.
- +Enhances reliability with guardrails and human-in-the-loop features.
- +Provides visibility into agent behavior through built-in tracing.
- +Supports real-time voice applications, expanding use cases.
Weaknesses
- -Requires Python 3.10 or newer, which might be a barrier for some legacy environments.
- -Voice and Redis session support require optional package installations.
- -The framework's power might introduce a learning curve for new users unfamiliar with agentic AI concepts.
Key features
Vellum AI
Build, debug, and deploy AI agents and workflows with a no-code builder or SDK.
Strengths
- +Accelerates AI development timelines significantly
- +Facilitates collaboration between technical and non-technical teams
- +Provides robust debugging and iteration capabilities
- +Supports complex agentic systems with advanced control flow
- +Offers flexible deployment options (host yourself or deploy to Vellum)
Weaknesses
- -No explicit free tier mentioned, suggesting it might be a paid-only solution
- -Requires some understanding of AI concepts for advanced use cases
Key features
Pricing: OpenAI Agents SDK vs Vellum AI
| Plan | OpenAI Agents SDK | Vellum AI |
|---|---|---|
| Tier 1 | Free Open Source | $0 monthly Free |
| Tier 2 | N/A | $25 monthly Pro |
| Tier 3 | N/A | $50 monthly Business |
| Tier 4 | N/A | Contact us Enterprise |
Pricing verified from each vendor's public pricing page. Compare in detail on OpenAI Agents SDK pricing and Vellum AI pricing.
Who Should Use What?
On a budget?
OpenAI Agents SDK is free. Vellum AI is freemium.
Go with: OpenAI Agents SDK
Want the highest-rated option?
Neither has ratings yet.
Too early to call on ratings — compare on features and pricing.
Value user reviews?
Neither has ratings yet.
Too early to call — neither has ratings yet.
3 Questions to Help You Decide
What's your budget?
OpenAI Agents SDK is free. Vellum AI is freemium. Go with OpenAI Agents SDK if free matters most.
What's your use case?
OpenAI Agents SDK is a AI assistants tool. Vellum AI is in AI agents. Pick the category that matches your needs.
How important are ratings?
Neither has ratings yet.
Key Takeaways
OpenAI Agents SDK
- Completely free
- Our pick for this comparison
Vellum AI
- Better fit for AI agents
The Bottom Line
OpenAI Agents SDK is our pick.
Frequently Asked Questions
Is OpenAI Agents SDK or Vellum AI better?
OpenAI Agents SDK is rated in our evaluation. OpenAI Agents SDK is free and Vellum AI is freemium.
What are OpenAI Agents SDK and Vellum AI used for?
OpenAI Agents SDK: A lightweight, powerful Python framework for building multi-agent AI workflows.. Vellum AI: Build, debug, and deploy AI agents and workflows with a no-code builder or SDK..
What does OpenAI Agents SDK cost vs Vellum AI?
OpenAI Agents SDK is completely free. Vellum AI is freemium (free tier + paid plans). Visit their websites for detailed pricing.