Vellum AI

Vellum AI is an LLM development platform that helps product and engineering teams build, evaluate, deploy, and monitor LLM-powered applications. The platform centers on prompt engineering, a visual Workflows builder for agentic and multi-step pipelines, evaluation suites with dataset management, retrieval-augmented generation, and production observability with logs, traces, and metrics. Target customers are AI product teams at startups and enterprises that need version control, collaboration, and vendor-neutral access across OpenAI, Anthropic, Google, Mistral, and open models. Vellum exposes a REST API plus Python and TypeScript SDKs, runs in cloud and self-hosted deployments, and offers tiered pricing for Pro/Business/Enterprise. Note: as of 2026 the vellum.ai marketing surface has been refocused on a personal AI assistant product; the developer platform documented here remains the LLM application stack.

Vellum AI publishes 15 APIs on the APIs.io network, including Default API, subpackage_deployments API, subpackage_documentIndexes API, and 12 more. Tagged areas include LLM Platform, Prompt Engineering, Workflows, Evaluations, and LLMOps.

Vellum AI’s developer surface includes authentication, documentation, engineering blog, pricing, signup flow, and 10 more developer resources.

🌐 Visit website 📡 Source on GitHub

38.5/100 thin ▬ flat Agent 36/100 agent ready Full breakdown ↓
scored 2026-08-20 · rubric v0.12.0

AccessFreeSelf serve⚡ Free to try

16 APIs

LLM PlatformPrompt EngineeringWorkflowsEvaluationsLLMOpsRAGObservabilityDatasetsDeploymentMulti-ProviderAgent BuilderSelf-Hosted

Kin Score

Kin Score How this is scored →
scored 2026-08-20 · rubric v0.12.0

Composite quality — 38.5/100 · thin

Contract Quality 13.3 / 25

Developer Ergonomics 4.8 / 20

Access Clarity 9.2 / 20

Operational Transparency 3.1 / 13

Contract Governance 0.0 / 12

Discoverability 8.2 / 10

Agent readiness — 36/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/vellum: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 16

Individual APIs this provider publishes, each with its own machine-readable definition.

Open Collections 17

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

Rate Limits 1

Documented rate limits and quota policies.

Vellum Rate Limits

2 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Get Started 2

Portal, sign-up, and the first successful call

Signup

Signup

Login

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

LlmsText

LlmsText

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Commercial 3

Pricing, plans, and the legal terms of use

Pricing

Pricing

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 4

The organization behind the API

Website

Website

Blog

Blog

Twitter

Twitter

LinkedIn

Source (apis.yml)

aid: vellum
name: Vellum AI
description: 'Vellum AI is an LLM development platform that helps product and engineering teams build, evaluate, deploy, and
  monitor LLM-powered applications. The platform centers on prompt engineering, a visual Workflows builder for agentic and
  multi-step pipelines, evaluation suites with dataset management, retrieval-augmented generation, and production observability
  with logs, traces, and metrics. Target customers are AI product teams at startups and enterprises that need version control,
  collaboration, and vendor-neutral access across OpenAI, Anthropic, Google, Mistral, and open models. Vellum exposes a REST
  API plus Python and TypeScript SDKs, runs in cloud and self-hosted deployments, and offers tiered pricing for Pro/Business/Enterprise.
  Note: as of 2026 the vellum.ai marketing surface has been refocused on a personal AI assistant product; the developer platform
  documented here remains the LLM application stack.'
type: Index
accessModel:
  pricing: free
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  label: Free · Self-serve signup
  confidence: high
  source:
  - plans
  - authentication
  generated: '2026-07-22'
  method: derived
position: Provider
access: 3rd-Party
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/vellum.png
tags:
- LLM Platform
- Prompt Engineering
- Workflows
- Evaluations
- LLMOps
- RAG
- Observability
- Datasets
- Deployment
- Multi-Provider
- Agent Builder
- Self-Hosted
tags_raw:
- LLM Platform
- Prompt Engineering
- Workflows
- Evaluations
- LLM Ops
- RAG
- Observability
- Datasets
- Deployments
- Multi-Provider
- Agent Builder
- Self-Hosted
url: https://raw.githubusercontent.com/api-evangelist/vellum/refs/heads/main/apis.yml
created: '2026-05-23'
modified: '2026-05-23'
specificationVersion: '0.23'
apis:
- aid: vellum:llm-platform
  name: Vellum LLM Platform API
  description: The Vellum REST API exposes prompts, workflows, evaluations, datasets, document indexes, deployments, and execution
    endpoints so developers can run versioned LLM pipelines from their own backends and capture logs and metrics for production
    monitoring.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - Prompts
  - Workflows
  - Evaluations
  - Datasets
  - Documents
  - Deployment
  - Execution
  - Monitoring
  tags_raw:
  - Prompts
  - Workflows
  - Evaluations
  - Datasets
  - Documents
  - Deployments
  - Executions
  - Monitoring
  properties:
  - type: Documentation
    url: https://docs.vellum.ai
  - type: APIReference
    url: https://docs.vellum.ai/api-reference
  - type: GettingStarted
    url: https://docs.vellum.ai/welcome/getting-started
  - type: Signup
    url: https://app.vellum.ai/signup
  - type: SDKs
    url: https://github.com/vellum-ai/vellum-client-python
  - type: SDKs
    url: https://github.com/vellum-ai/vellum-client-typescript
  - type: GitHubOrganization
    url: https://github.com/vellum-ai
  - type: Pricing
    url: https://www.vellum.ai/pricing
  - type: Blog
    url: https://www.vellum.ai/blog
  features:
  - name: Prompt Engineering Workbench
    description: Versioned prompts, side-by-side model comparisons, and structured prompt variables.
  - name: Workflows Builder
    description: Visual builder for multi-step LLM pipelines including branching, tools, and RAG nodes.
  - name: Evaluation Suites
    description: Run dataset-driven evals with built-in and custom metrics for prompts and workflows.
  - name: Dataset Management
    description: Store labeled test cases and production examples to drive evaluations and fine-tuning.
  - name: Document Indexes / RAG
    description: Managed document ingestion, embeddings, and retrieval for grounded generation.
  - name: Deployments and Versioning
    description: Promote prompts and workflows through environments with rollback and traffic splits.
  - name: Production Monitoring
    description: Logs, traces, latency, cost, and quality metrics for every execution.
  - name: Multi-Provider Routing
    description: Vendor-neutral access to OpenAI, Anthropic, Google, Mistral, and open models.
  - name: SDKs for Python and TypeScript
    description: First-class SDKs for invoking prompts, workflows, and datasets from application code.
  - name: Self-Hosted Option
    description: Deploy Vellum into the customer's own cloud for compliance-sensitive workloads.
  useCases:
  - name: Build Production LLM Apps
    description: Iterate on prompts and workflows, then deploy versioned endpoints into apps.
  - name: Evaluate LLM Quality
    description: Use datasets and evals to measure regressions across models and prompt variants.
  - name: Build Agents
    description: Compose tools, retrieval, and conditional logic via the visual workflow builder.
  - name: RAG Pipelines
    description: Ingest documents, index them, and query through Vellum's managed retrieval layer.
  - name: Observe and Debug
    description: Trace production runs to debug failures and improve quality over time.
  integrations:
  - name: OpenAI
  - name: Anthropic
  - name: Google
  - name: Mistral
  - name: Cohere
  - name: AWS Bedrock
  - name: Azure OpenAI
  - name: Pinecone
  - name: Snowflake
  - name: LangChain
  - name: LlamaIndex
  authentication:
  - type: API Key
    description: Workspace API keys passed via the `X_API_KEY` header authenticate REST and SDK calls.
- aid: vellum:vellum-default-api
  name: Vellum AI Default API
  description: The Default API from Vellum AI — 8 operation(s) for default.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags: []
  tags_raw:
  - Default
  properties:
  - type: OpenAPI
    url: openapi/vellum-default-api-openapi.yml
- aid: vellum:vellum-subpackage-deployments-api
  name: Vellum AI subpackage_deployments API
  description: The subpackage_deployments API from Vellum AI — 7 operation(s) for subpackage_deployments.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags: []
  tags_raw:
  - subpackage_deployments
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-deployments-api-openapi.yml
- aid: vellum:vellum-subpackage-documentindexes-api
  name: Vellum AI subpackage_documentIndexes API
  description: The subpackage_documentIndexes API from Vellum AI — 3 operation(s) for subpackage_documentindexes.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - subpackage_documentIndexes
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-documentindexes-api-openapi.yml
- aid: vellum:vellum-subpackage-documents-api
  name: Vellum AI subpackage_documents API
  description: The subpackage_documents API from Vellum AI — 3 operation(s) for subpackage_documents.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags: []
  tags_raw:
  - subpackage_documents
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-documents-api-openapi.yml
- aid: vellum:vellum-subpackage-events-api
  name: Vellum AI subpackage_events API
  description: The subpackage_events API from Vellum AI — 1 operation(s) for subpackage_events.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags: []
  tags_raw:
  - subpackage_events
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-events-api-openapi.yml
- aid: vellum:vellum-subpackage-folderentities-api
  name: Vellum AI subpackage_folderEntities API
  description: The subpackage_folderEntities API from Vellum AI — 2 operation(s) for subpackage_folderentities.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - subpackage_folderEntities
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-folderentities-api-openapi.yml
- aid: vellum:vellum-subpackage-sandboxes-api
  name: Vellum AI subpackage_sandboxes API
  description: The subpackage_sandboxes API from Vellum AI — 3 operation(s) for subpackage_sandboxes.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags: []
  tags_raw:
  - subpackage_sandboxes
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-sandboxes-api-openapi.yml
- aid: vellum:vellum-subpackage-testsuiteruns-api
  name: Vellum AI subpackage_testSuiteRuns API
  description: The subpackage_testSuiteRuns API from Vellum AI — 3 operation(s) for subpackage_testsuiteruns.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - subpackage_testSuiteRuns
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-testsuiteruns-api-openapi.yml
- aid: vellum:vellum-subpackage-testsuites-api
  name: Vellum AI subpackage_testSuites API
  description: The subpackage_testSuites API from Vellum AI — 3 operation(s) for subpackage_testsuites.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - subpackage_testSuites
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-testsuites-api-openapi.yml
- aid: vellum:vellum-subpackage-uploadedfiles-api
  name: Vellum AI subpackage_uploadedFiles API
  description: The subpackage_uploadedFiles API from Vellum AI — 1 operation(s) for subpackage_uploadedfiles.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - subpackage_uploadedFiles
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-uploadedfiles-api-openapi.yml
- aid: vellum:vellum-subpackage-workflowdeployments-api
  name: Vellum AI subpackage_workflowDeployments API
  description: The subpackage_workflowDeployments API from Vellum AI — 10 operation(s) for subpackage_workflowdeployments.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - subpackage_workflowDeployments
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-workflowdeployments-api-openapi.yml
- aid: vellum:vellum-subpackage-workflowexecutions-api
  name: Vellum AI subpackage_workflowExecutions API
  description: The subpackage_workflowExecutions API from Vellum AI — 1 operation(s) for subpackage_workflowexecutions.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - subpackage_workflowExecutions
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-workflowexecutions-api-openapi.yml
- aid: vellum:vellum-subpackage-workflows-api
  name: Vellum AI subpackage_workflows API
  description: The subpackage_workflows API from Vellum AI — 1 operation(s) for subpackage_workflows.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags: []
  tags_raw:
  - subpackage_workflows
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-workflows-api-openapi.yml
- aid: vellum:vellum-subpackage-workflowsandboxes-api
  name: Vellum AI subpackage_workflowSandboxes API
  description: The subpackage_workflowSandboxes API from Vellum AI — 1 operation(s) for subpackage_workflowsandboxes.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - subpackage_workflowSandboxes
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-workflowsandboxes-api-openapi.yml
- aid: vellum:vellum-subpackage-workspacesecrets-api
  name: Vellum AI subpackage_workspaceSecrets API
  description: The subpackage_workspaceSecrets API from Vellum AI — 1 operation(s) for subpackage_workspacesecrets.
  humanURL: https://docs.vellum.ai
  baseURL: https://api.vellum.ai
  tags:
  - subpackage_workspaceSecrets
  properties:
  - type: OpenAPI
    url: openapi/vellum-subpackage-workspacesecrets-api-openapi.yml
common:
- type: AgenticAccess
  url: agentic-access/vellum-agentic-access.yml
- type: DomainSecurity
  url: security/vellum-domain-security.yml
- type: Authentication
  url: authentication/vellum-authentication.yml
- type: Website
  url: https://www.vellum.ai
- type: Documentation
  url: https://docs.vellum.ai
- type: Blog
  url: https://www.vellum.ai/blog
- type: GitHubOrganization
  url: https://github.com/vellum-ai
- type: Pricing
  url: https://www.vellum.ai/pricing
- type: Signup
  url: https://app.vellum.ai/signup
- type: Login
  url: https://app.vellum.ai/login
- type: TermsOfService
  url: https://www.vellum.ai/terms-of-service
- type: PrivacyPolicy
  url: https://www.vellum.ai/privacy-policy
- type: Twitter
  url: https://x.com/vellum_ai
- type: LinkedIn
  url: https://www.linkedin.com/company/vellum-ai
- type: LlmsText
  url: https://docs.vellum.ai/llms.txt
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com