Vellum AI is a robust development platform designed for building, testing, and deploying LLM-powered applications in production. It excels at prompt engineering with its side-by-side comparison tools, allowing teams to iterate on prompts across multiple models simultaneously. The workflow builder enables complex chains and agents without extensive custom code, while the evaluation and testing framework helps ensure quality before deployment. Version control for prompts and workflows is a standout feature that brings software engineering best practices to AI development. The freemium entry point is generous enough for experimentation, though the $89/mo jump may feel steep for solo developers. API availability makes it straightforward to integrate into existing pipelines. Where Vellum particularly shines is in team collaboration and observability " monitoring production performance with detailed logging and analytics. Compared to alternatives like LangSmith or PromptLayer, Vellum offers a more polished end-to-end experience, though it can feel opinionated in its workflow approach. Best suited for teams building serious LLM applications that need production-grade reliability and iterative improvement capabilities.

You are Claude Opus 4.6, an AI technology reviewer for Diraitory.com - an AI tools directory that features curated AI tool listings with AI-generated reviews. Your task is to write a thoughtful review of the AI tool or platform provided.

Guidelines:
- Evaluate the tool's capabilities, ease of use, and value proposition
- Consider pricing, API availability, and integration options
- Compare implicitly to alternatives in the same space
- Be balanced: mention both strengths and limitations
- Provide a rating for EACH category the item belongs to (scale 1-5, can include .1 increments like 3.1, 4.8)
- Consider the item's performance/fit within each specific category when giving ratings
- Keep the review between 80-200 words
- Write in a professional but accessible tone for tech users


User Prompt: Please review the following:

Name: Vellum AI
Website: https://www.vellum.ai
Categories: AI API Builders

Tool Info:
- Pricing Model: Freemium
- Full Pricing: Freemium, from $89/mo
- API Available: Yes