Sim vs Vellum

Sim is an open-source AI workspace where teams build, deploy, and manage AI agents visually, conversationally, or with code. Vellum is an enterprise AI development platform for building, evaluating, and deploying LLM prompts, workflows, and agents. Teams considering a switch typically weigh licensing (Sim is Apache 2.0 and self-hostable), pricing model, and how AI-native the platform's agent-building experience is.

Sim is built specifically as an AI agent workspace, with native multi-LLM support, an in-editor AI Copilot, and a knowledge base with hybrid vector + keyword search. Vellum's standout capability is HIPAA compliance with a signable BAA: Vellum is HIPAA compliant and enterprise customers can sign a Business Associate Agreement for handling protected health information, corroborated by a third-party Drata case study. Sim does not currently offer HIPAA compliance (both platforms hold SOC 2 Type 2). One documented limitation of Vellum is brand/product ambiguity as of mid-2026: Vellum's homepage, pricing page, security docs, and several product pages now serve content for a new consumer 'Personal Intelligence' assistant (an open-source, MIT-licensed Mac app) instead of the original enterprise workflow, evaluations, and prompt-engineering platform. That makes enterprise-specific details, like environment promotion, version-control depth, tracing, alerting, and integration counts, harder to verify from the public site alone.

Sim can be self-hosted via Docker or Kubernetes under an Apache 2.0 license, in addition to a managed cloud-hosted plan. Vellum's self-hosting position: Yes: self-hosted / VPC install available for enterprise customers.

Sim uses credit-based usage billing (Stripe), with bring-your-own-key exemption from metered caps. Vellum uses not publicly listed for the B2B enterprise platform: Vellum's current pricing page has been fully replaced by the unrelated consumer 'Personal Intelligence' product's plans.

Security is a like-for-like comparison, not a one-line verdict. Sim: SOC2. Vellum: HIPAA compliant, with a BAA available for enterprise customers; no other certifications (ISO 27001, GDPR-specific attestation, PCI, FedRAMP) confirmed. Check the Security & compliance rows above for the full breakdown, including SSO, audit logging, and data residency.

Sim: 21 provider integrations (OpenAI, Anthropic, Google/Gemini, Azure OpenAI, Azure Anthropic, Groq, Cerebras, Mistral, xAI, Bedrock, Vertex, Ollama, OpenRouter, and more), with OpenRouter, LiteLLM, vLLM, and Ollama resolving models dynamically at runtime rather than from a fixed list, so effective model reach extends well beyond the 21 named providers. Vellum: model-agnostic across 20-23+ providers (OpenAI, Anthropic, Google/Gemini, Cohere, Azure OpenAI, Bedrock, Fireworks, Perplexity, Cerebras, Groq, etc. Sim also ships native human-in-the-loop approvals, a hybrid vector-plus-keyword knowledge base, and an in-editor AI Copilot that can read execution logs and directly edit the workflow to fix a failed run.

Documented limitations of Vellum include brand/product ambiguity as of mid-2026: Vellum's homepage, pricing page, security docs, and several product pages now serve content for a new consumer 'Personal Intelligence' assistant (an open-source, MIT-licensed Mac app) instead of the original enterprise workflow, evaluations, and prompt-engineering platform. That makes enterprise-specific details, like environment promotion, version-control depth, tracing, alerting, and integration counts, harder to verify from the public site alone.; BYOK not documented on pricing: Vellum's pricing pages describe a prepaid-credit model that passes through LLM costs at cost, with no bring-your-own-API-key option mentioned as an alternative.; no enterprise SLA published: No uptime or response-time SLA commitments are published on the enterprise or pricing pages.; no native spreadsheet-style data tables: No Vellum documentation describes a native, spreadsheet-like data-table object with persistent rows/columns, keyboard navigation, or per-row writes from workflows; the closest documented tabular handling is uploading CSV/XLS files and extracting or generating structured output within workflow nodes, unlike Sim, which has a built-in Tables feature.

There is no automated one-click migration tool between Vellum and Sim. Workflows and automations need to be rebuilt in Sim's visual builder, natural-language Chat surface, or API. Most teams start by recreating their highest-value automation first to validate the switch before migrating the rest.

Not in the same sense. Vellum is an enterprise AI development platform for building, evaluating, and deploying LLM prompts, workflows, and agents. Sim, by contrast, is a visual and code-based workflow builder that deploys agents as REST APIs, scheduled jobs, or chat interfaces, so the two solve different parts of the AI agent problem rather than competing feature-for-feature.