How does Vellum compare to Langflow in 2026?
Quick Answer: As of April 2026, Vellum is a developer platform for production LLM apps focused on prompt management, evaluation, and deployment, while Langflow is an open-source visual builder for LangChain flows. Vellum wins on eval, observability, and prompt versioning; Langflow wins on visual prototyping and zero-cost self-hosting.
Vellum vs Langflow in 2026
Vellum and Langflow both help teams build LLM applications, but they sit at different points in the lifecycle. As of April 2026, many teams use Langflow for prototyping and Vellum for production.
Positioning
- Vellum — Closed-source SaaS focused on production LLM ops: prompt management, eval, observability, and deployment.
- Langflow — Open-source visual builder (MIT) for LangChain flows; managed hosting via DataStax.
Authoring Experience
- Vellum — Web-based prompt and workflow editor with versioning, branching, and A/B testing built in. Code-aware components for chains and agents.
- Langflow — Drag-and-drop canvas with a Figma-style node graph for LangChain components (chains, agents, retrievers, vector stores).
Evaluation
- Vellum — First-class eval suites: golden datasets, automated metrics (exact match, semantic similarity, custom Python), regression detection across prompt versions.
- Langflow — Limited built-in eval; teams typically pair with LangSmith for tracing and eval.
Deployment
- Vellum — Hosts deployed prompts and workflows behind a stable REST endpoint with semantic versioning.
- Langflow — Self-host or DataStax-managed; flow exposed at
/api/v1/run/<flow_id>. Versioning is git-based via JSON exports.
Pricing
- Vellum — Custom pricing; typical starts in the low five figures annually for production usage.
- Langflow — Free self-hosted; DataStax Astra usage-based.
Selection Summary
- Production LLM ops with eval: Vellum
- Visual prototyping: Langflow
- Open-source requirement: Langflow
- Prompt versioning and A/B: Vellum