Understudy Labs

Understudy Labs (YC S26) is an LLM gateway and model-optimization platform that helps teams move repeated production LLM workloads onto open-weight models they own. The Understudy gateway is a drop-in replacement for the Anthropic and OpenAI API endpoints that captures request/response traces by project and workload, routes measured slices of traffic to managed open models, and falls back safely. A REST control plane manages keys, projects, workloads, routing, captures, evaluation cohorts, and reporting, while the MIT-licensed understudy-agent-tools repo ships a CLI, a coding-agent skill library, a local MCP server, and Understudy Desktop with a documented loopback OpenAPI 3.1 contract.

Understudy Labs publishes 12 APIs on the APIs.io network, including Capabilities API, Conversations API, Downloads API, and 9 more. Tagged areas include Artificial Intelligence, LLM Gateway, Machine Learning, Open Source, and Model Routing.

Understudy Labs’ developer surface includes authentication, documentation, API reference, getting-started guide, support, engineering blog, CLI, and 21 more developer resources.

🌐 Visit website 📡 Source on GitHub

42.7/100 developing ▬ flat Agent 29/100 agent ready Front door AI 3/6 light saas Full breakdown ↓
scored 2026-09-25 · rubric v0.23.0

1 APIs 1 MCP Servers

Artificial Intelligence LLM Gateway Machine Learning Open Source Model Routing Evaluation Fine-Tuning AI Infrastructure Developer Tools

Kin Score

Kin Score How this is scored →
scored 2026-09-25 · rubric v0.23.0

Composite quality — 42.7/100 · developing

Contract Quality 8.1 / 19

Developer Ergonomics 10.7 / 15

Access Clarity 4.1 / 15

Operational Transparency 1.8 / 10

Contract Governance 1.6 / 9

Discoverability 5.4 / 8

Regulatory Posture 3.4 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 29/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 12 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/understudy-labs: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 1

Interfaces this provider implements that became standards by being copied rather than ratified. Each is profiled by the API Commons, and the evidence column says how the claim was established — not that it was made.

The OpenAI Interface

declared — publishes a spec that declares them

2 core of 338 operations graded · api-commons/models

APIs 12

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

Understudy Gateway API

Anthropic- and OpenAI-compatible LLM proxy at api.understudylabs.com. POST /v1/messages (Anthropic Messages), POST /v1/chat/completions (OpenAI Chat Completions), POST /v1/messa...

Understudy Control Plane API

REST surface behind the dashboard and CLI, served from the gateway host under /admin/v1 and /customer/v1, org-scoped and authenticated with sk_* bearer keys. Covers API key mint...

Understudy Labs Capabilities API

The Capabilities API from Understudy Labs — 1 operation(s) for capabilities.

Understudy Labs Conversations API

The Conversations API from Understudy Labs — 1 operation(s) for conversations.

Understudy Labs Downloads API

The Downloads API from Understudy Labs — 3 operation(s) for downloads.

Understudy Labs Feedback API

The Feedback API from Understudy Labs — 1 operation(s) for feedback.

Understudy Labs Metrics API

The Metrics API from Understudy Labs — 1 operation(s) for metrics.

Understudy Labs Models API

The Models API from Understudy Labs — 2 operation(s) for models.

Understudy Labs Residency API

The Residency API from Understudy Labs — 6 operation(s) for residency.

Understudy Labs Runs API

The Runs API from Understudy Labs — 2 operation(s) for runs.

Understudy Labs Status API

The Status API from Understudy Labs — 1 operation(s) for status.

Understudy Labs Supervision API

The Supervision API from Understudy Labs — 1 operation(s) for supervision.

Scroll for all 12

Open Collections 11

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

API Collection

OPEN COLLECTION

Understudy Desktop Agent Capabilities API

OPEN COLLECTION

Understudy Desktop Agent Capabilities Conversations API

OPEN COLLECTION

Understudy Desktop Agent Capabilities Downloads API

OPEN COLLECTION

Understudy Desktop Agent Capabilities Feedback API

OPEN COLLECTION

Understudy Desktop Agent Capabilities Metrics API

OPEN COLLECTION

Understudy Desktop Agent Capabilities Models API

OPEN COLLECTION

Understudy Desktop Agent Capabilities Residency API

OPEN COLLECTION

Understudy Desktop Agent Capabilities Runs API

OPEN COLLECTION

Understudy Desktop Agent Capabilities Status API

OPEN COLLECTION

Understudy Desktop Agent Capabilities Supervision API

OPEN COLLECTION

Scroll for all 11

Arazzo Workflows 1

Multi-step API workflows described with the Arazzo specification.

Download, warm, and chat with a local model on Understudy Desktop

The core Understudy Desktop journey over the loopback Agent API - pick a model from the catalog, start and track its download, add a residency slot, assign and warm the model in...

ARAZZO

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

Understudy Labs MCP Server

MCP SERVER

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Understudy Labs Authentication

apiKey/http · 5 schemes

SECURITY

Understudy Labs Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Understudy Labs Agentic Access

20 operations · 10 acting · 1 human-in-the-loop

20 operations · 10 acting

AGENTIC

Resources

Get Started 3

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

Login

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 5

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

LLMsTxt

WellKnown

MCPServer

AgentSkill

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

ErrorCatalog

Conventions

Lifecycle

Conformance

DataModel

Arazzo

Build 3

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Packages

Packages

CLI

CLI

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

Support

Support

ChangeLog

ChangeLog

Commercial 2

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Overlay

Overlay

Source (apis.yml)

aid: understudy-labs
name: Understudy Labs
description: Understudy Labs (YC S26) is an LLM gateway and model-optimization platform that helps teams move repeated production
  LLM workloads onto open-weight models they own. The Understudy gateway is a drop-in replacement for the Anthropic and OpenAI
  API endpoints that captures request/response traces by project and workload, routes measured slices of traffic to managed
  open models, and falls back safely. A REST control plane manages keys, projects, workloads, routing, captures, evaluation
  cohorts, and reporting, while the MIT-licensed understudy-agent-tools repo ships a CLI, a coding-agent skill library, a
  local MCP server, and Understudy Desktop with a documented loopback OpenAPI 3.1 contract.
url: https://raw.githubusercontent.com/api-evangelist/understudy-labs/refs/heads/main/apis.yml
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - security
  generated: '2026-09-03'
  method: derived
image: https://bookface-images.s3.amazonaws.com/small_logos/034b1bab6d92bd99439aee47bf2312630046798c.png
x-type: company
x-source: vc-portfolio
x-backed-by:
- y-combinator
x-tier: profile
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-21'
tags:
- Artificial Intelligence
- LLM Gateway
- Machine Learning
- Open Source
- Model Routing
- Evaluation
- Fine-Tuning
- AI Infrastructure
- Developer Tools
tags_raw:
- Artificial Intelligence
- LLM Gateway
- Machine Learning
- Open Source
- Model Routing
- Evaluations
- Fine-Tuning
- AI Infrastructure
- Developer Tools
- Machine-Learning
- Open-Source
apis:
- aid: understudy-labs:understudy-gateway-api
  name: Understudy Gateway API
  description: Anthropic- and OpenAI-compatible LLM proxy at api.understudylabs.com. POST /v1/messages (Anthropic Messages),
    POST /v1/chat/completions (OpenAI Chat Completions), POST /v1/messages/count_tokens, GET /v1/models (public managed-model
    catalog), and GET /healthz. Supports bring-your-own-key passthrough and managed catalog models, capture of request/response
    evidence, canary routing with fallback, and x-understudy-* scoping, tagging, and legibility headers.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - LLM Gateway
  - Proxy
  - Model Routing
  properties:
  - type: Documentation
    url: https://docs.understudylabs.com/reference/proxy-endpoints
  - type: APIReference
    url: https://docs.understudylabs.com/reference/request-headers
- aid: understudy-labs:understudy-control-plane-api
  name: Understudy Control Plane API
  description: REST surface behind the dashboard and CLI, served from the gateway host under /admin/v1 and /customer/v1, org-scoped
    and authenticated with sk_* bearer keys. Covers API key mint/list/revoke, project CRUD by slug, workload CRUD, the model
    catalog, route writes with traffic percentages, capture listing and envelope fetch, evaluation capture catalogs with frozen
    cohorts and audited short-lived exports, and reporting endpoints for routing status, provider health, workload status,
    and usage summaries.
  humanURL: https://docs.understudylabs.com/reference/control-plane
  baseURL: https://api.understudylabs.com
  tags:
  - Control Plane
  - APIKeys
  - Routing
  - Evaluation
  tags_raw:
  - Control Plane
  - API Keys
  - Routing
  - Evaluations
  properties:
  - type: Documentation
    url: https://docs.understudylabs.com/reference/control-plane
  - type: APIReference
    url: https://docs.understudylabs.com/reference/control-plane/keys
- aid: understudy-labs:understudy-labs-capabilities-api
  name: Understudy Labs Capabilities API
  description: The Capabilities API from Understudy Labs — 1 operation(s) for capabilities.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Capabilities
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-capabilities-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
- aid: understudy-labs:understudy-labs-conversations-api
  name: Understudy Labs Conversations API
  description: The Conversations API from Understudy Labs — 1 operation(s) for conversations.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Conversations
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-conversations-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
- aid: understudy-labs:understudy-labs-downloads-api
  name: Understudy Labs Downloads API
  description: The Downloads API from Understudy Labs — 3 operation(s) for downloads.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Downloads
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-downloads-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
- aid: understudy-labs:understudy-labs-feedback-api
  name: Understudy Labs Feedback API
  description: The Feedback API from Understudy Labs — 1 operation(s) for feedback.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Feedback
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-feedback-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
- aid: understudy-labs:understudy-labs-metrics-api
  name: Understudy Labs Metrics API
  description: The Metrics API from Understudy Labs — 1 operation(s) for metrics.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Metrics
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-metrics-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
- aid: understudy-labs:understudy-labs-models-api
  name: Understudy Labs Models API
  description: The Models API from Understudy Labs — 2 operation(s) for models.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Models
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-models-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
- aid: understudy-labs:understudy-labs-residency-api
  name: Understudy Labs Residency API
  description: The Residency API from Understudy Labs — 6 operation(s) for residency.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Residency
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-residency-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
- aid: understudy-labs:understudy-labs-runs-api
  name: Understudy Labs Runs API
  description: The Runs API from Understudy Labs — 2 operation(s) for runs.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Runs
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-runs-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
- aid: understudy-labs:understudy-labs-status-api
  name: Understudy Labs Status API
  description: The Status API from Understudy Labs — 1 operation(s) for status.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Status
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-status-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
- aid: understudy-labs:understudy-labs-supervision-api
  name: Understudy Labs Supervision API
  description: The Supervision API from Understudy Labs — 1 operation(s) for supervision.
  humanURL: https://docs.understudylabs.com/reference/proxy-endpoints
  baseURL: https://api.understudylabs.com
  tags:
  - Supervision
  properties:
  - type: OpenAPI
    url: openapi/understudy-labs-supervision-api-openapi.yml
  - type: Documentation
    url: https://docs.understudylabs.com/open-source/desktop-task-models
common:
- type: Overlay
  url: overlays/understudy-labs-desktop-api-overlay.yaml
- type: AgenticAccess
  url: agentic-access/understudy-labs-agentic-access.yml
- type: Authentication
  url: authentication/understudy-labs-authentication.yml
- type: DomainSecurity
  url: security/understudy-labs-domain-security.yml
- type: Website
  url: https://understudylabs.com
- type: DeveloperPortal
  url: https://docs.understudylabs.com
- type: Documentation
  url: https://docs.understudylabs.com
- type: APIReference
  url: https://docs.understudylabs.com/reference/proxy-endpoints
- type: GettingStarted
  url: https://docs.understudylabs.com/quickstart
- type: Login
  url: https://app.understudylabs.com
- type: Support
  url: https://understudylabs.com/contact
- type: Blog
  url: https://understudylabs.com/research
- type: GitHubOrganization
  url: https://github.com/understudylabs
- type: TermsOfService
  url: https://understudylabs.com/terms
- type: PrivacyPolicy
  url: https://understudylabs.com/privacy
- type: LLMsTxt
  url: llms/understudy-labs-llms.txt
- type: WellKnown
  url: well-known/understudy-labs-well-known.yml
- type: MCPServer
  url: mcp/understudy-labs-mcp.yml
- type: AgentSkill
  url: skills/_index.yml
- type: ErrorCatalog
  url: errors/understudy-labs-problem-types.yml
- type: Conventions
  url: conventions/understudy-labs-conventions.yml
- type: Lifecycle
  url: lifecycle/understudy-labs-lifecycle.yml
- type: Conformance
  url: conformance/understudy-labs-conformance.yml
- type: Packages
  url: packages/understudy-labs-packages.yml
- type: CLI
  url: cli/understudy-labs-cli.yml
- type: ChangeLog
  url: changelog/understudy-labs-changelog.yml
- type: DataModel
  url: data-model/understudy-labs-data-model.yml
- type: Arazzo
  url: arazzo/understudy-labs-download-warm-and-chat.yml
  name: Download, warm, and chat with a local model on Understudy Desktop
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
x-enrichment:
  date: '2026-07-21'
  status: enriched
  artifacts_added: 24
  pass: local-v1

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