Vellum

What it is

Vellum is a developer-first stack: prompt management, evals, and deployment for LLM-powered features. Best fit for engineering teams shipping AI in production, not for no-code operators.

Notes from using it

Vellum is the right call when you've outgrown notebook-style prompt iteration and need real engineering rigor around your LLM features. Prompt versioning, eval harnesses, A/B testing of prompts in production — Vellum gives you the control plane these workflows need.

The team-fit is specific: ML or AI-platform engineers who own LLM features in production. Business users won't touch Vellum directly; the visual workflow surface is for engineering review, not non-technical iteration. Teams that want "both engineering and ops to use the same tool" should look at Stack AI or Dust instead.

The pricing model rewards thoughtful traffic management. Free dev tier and Team at $500/mo cover most teams running modest LLM features; high-traffic production workloads push you into Enterprise territory fast. Plan with caching and request batching from day one or the bill scales unpredictably.

Where it shines

• Strong eval and prompt-versioning tooling.
• Designed for production rigor, not demos.

Where it falls down

• Engineering-team only — no business-user surface.
• Pricing scales fast on heavy traffic.

Best fit for

If you're trying to put AI behind any of these functions, Vellum is worth a look:

• AI for Customer Support — Tier-1 chat, email triage, knowledge-base answers, ticket routing.
• AI for Content Writing — Blog posts, landing pages, social copy, newsletters.