Puma

Puma is a simple, fast, multi-threaded, and highly parallel HTTP 1.1 server for Ruby/Rack applications. It is the most popular Ruby web server and the default server for Ruby on Rails, supporting SSL, zero-downtime rolling restarts, and a built-in request bufferer. Puma is an open-source application server and not a hosted service, so it does not expose a public REST API; integration is through configuration, Rack middleware, and the Puma control application server.

Puma publishes 11 API contracts indexed on the APIs.io network, including Gc API, Gc Stats API, Halt API, and 8 more. Tagged areas include Web Server, Ruby, Rack, Application Server, and HTTP.

The Puma catalog on APIs.io includes 1 Spectral governance ruleset.

Puma’s developer surface includes authentication, documentation, and 16 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

36.6/100 thin ▬ flat Agent 19/100 agent aware Front door AI 1/6 silent Heartbeat 100/100 alive self hosted · BSD-3-Clause Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

1 published contract

Web Server RubyRackApplication Server HTTP Open Source

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 36.6/100 · thin

Contract Quality 8.7 / 19

Developer Ergonomics 3.9 / 15

Access Clarity 1.0 / 15

Operational Transparency 2.8 / 10

Contract Governance 1.2 / 9

Discoverability 5.0 / 8

Regulatory Posture 1.8 / 15

Open Source Surface 10.0 / 10

Agent readiness — 19/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 9 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 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 4 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 0 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

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.

Open Source Surface applies to this provider. This product is open source and we read its repository directly, so Open Source Surface carries 10 points of the composite. It is scored from what the repository actually publishes — a security policy, a contribution guide, a release history, a code of conduct — read live from the provider rather than inferred from our own catalog pointers. This facet adds; nothing was taken away to make room for it. An open-source project is not excused from the commercial facets, because exemption would strip it of the points it does earn. If we have the wrong repository, or this product is not open source, say so on your provider repo and we will drop the facet rather than have you publish against it.

Create-or-Update Ergonomics does not apply to this provider. The published contracts declare no write operations, and a read-only API cannot create-or-update. The facet is excluded from this provider's denominator entirely — not scored zero. A reference or data API is not deficient for being unable to upsert.

The six quality facets above are damped to 75 points between them, because both conditional facets apply and carry 25 points together. 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/.

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Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship Ask about this →
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes Ask about this →
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0 Ask about this →
Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented) Ask about this →
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link Ask about this →
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document Ask about this →

8 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Access Clarity scores 6.4 — up to +18.7 composite points Ask about this →
Developer Ergonomics scores 26.2 — up to +14.8 composite points Ask about this →
Contract Quality scores 46.5 — up to +13.4 composite points Ask about this →

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Not sure how this applies to your stack? Ask about any one item. Kin Lane reads every question, looks at your profile and your situation, and replies with what a fix would take — scoped to that one area, priced up front, yours whether you ship it or not. Ask a question →

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 the provider profile at artifacts.apis.io/puma/apis.yml: open an issue on github.com/api-evangelist/puma to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 2

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

HTTP

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

OpenAPI

measured — observed by APIs.io (published)

APIs 11

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

Puma Control/Status Application

Puma ships with an optional control/status HTTP application that can be bound to a local port or Unix socket and queried for runtime statistics (busy threads, worker status, bac...

Puma Gc API

The Gc API from Puma — 1 operation(s) for gc.

Puma Gc Stats API

The Gc Stats API from Puma — 1 operation(s) for gc stats.

Puma Halt API

The Halt API from Puma — 1 operation(s) for halt.

Puma Phased Restart API

The Phased Restart API from Puma — 1 operation(s) for phased restart.

Puma Refork API

The Refork API from Puma — 1 operation(s) for refork.

Puma Reload Worker Directory API

The Reload Worker Directory API from Puma — 1 operation(s) for reload worker directory.

Puma Restart API

The Restart API from Puma — 1 operation(s) for restart.

Puma Stats API

The Stats API from Puma — 1 operation(s) for stats.

Puma Stop API

The Stop API from Puma — 1 operation(s) for stop.

Puma Thread Backtraces API

The Thread Backtraces API from Puma — 1 operation(s) for thread backtraces.

Scroll for all 11

Open Collections 11

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

Puma Control/Status Application Gc API

OPEN COLLECTION

Puma Control/Status Application Gc Gc Stats API

OPEN COLLECTION

Puma Control/Status Application Gc Halt API

OPEN COLLECTION

Puma Control/Status Application Gc Phased Restart API

OPEN COLLECTION

Puma Control/Status Application Gc Refork API

OPEN COLLECTION

Puma Control/Status Application Gc Reload Worker Directory API

OPEN COLLECTION

Puma Control/Status Application Gc Restart API

OPEN COLLECTION

Puma Control/Status Application Gc Stats API

OPEN COLLECTION

Puma Control/Status Application Gc Stop API

OPEN COLLECTION

Puma Control/Status Application Gc Thread Backtraces API

OPEN COLLECTION

Puma Control/Status Application API

OPEN COLLECTION

Scroll for all 11

Terms of Service 1

What its API terms permit and prohibit, quoted from its own page.

Puma

5 quoted statements, read from Puma's own page on 2026-11-10.

TERMS

Data License 1

How its data and outputs may be reused, quoted from its own terms.

Puma

2 quoted statements, read from Puma's own page on 2026-11-10.

LICENSE

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs. Counts are the severity each rule declares, not results of running them.

Puma API Rules

50 rules · 48 error-severity 1 warn-severity 1 info-severity

SPECTRAL

Security Posture 2

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

Puma Authentication

apiKey · 1 scheme

SECURITY

Puma Domain Security

TLSv1.3

SECURITY

Agentic Access (API Evangelist recommendations) 1

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

Puma Agentic Access

10 operations

10 operations · 0 acting

AGENTIC

Resources

Documentation 2

Reference material describing how the API behaves

ContributionGuide

ContributionGuide

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Build 3

SDKs, sample code, and the tooling you integrate with

CodeOfConduct

CodeOfConduct

GitHubOrganization

GitHubOrganization

GitHubRepository

GitHubRepository

Access & Security 3

Authentication, authorization, and security posture

SecurityPolicy

SecurityPolicy

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 3

Status, limits, changes, and where to get help

Releases

Releases

Issues

Issues

Forums

Forums

Commercial 3

Pricing, plans, and the legal terms of use

License

License

UsageTerms

UsageTerms

DataLicense

DataLicense

Company 2

The organization behind the API

LinkedIn

Website

Website

Other 1

Properties that don't map to a standard resource type

RubyGems

RubyGems

Source (apis.yml)

aid: puma
name: Puma
description: Puma is a simple, fast, multi-threaded, and highly parallel HTTP 1.1 server for Ruby/Rack applications. It is
  the most popular Ruby web server and the default server for Ruby on Rails, supporting SSL, zero-downtime rolling restarts,
  and a built-in request bufferer. Puma is an open-source application server and not a hosted service, so it does not expose
  a public REST API; integration is through configuration, Rack middleware, and the Puma control application server.
type: Index
deliveryModel:
  model: self-hosted
  license: BSD-3-Clause
  license_evidence:
    repo: puma/puma
    spdx: BSD-3-Clause
    stars: 7917
  open_source: true
  commercial: false
  callable_host: false
  label: Self-hosted open source · you run it yourself
  confidence: medium
  source:
  - openapi
  - repository-license
  generated: '2026-09-25'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  try_now_blocked_by: loopback
  source:
  - authentication
  - security
  generated: '2026-11-13'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/puma.png
tags:
- Web Server
- Ruby
- Rack
- Application Server
- HTTP
- Open Source
tags_raw:
- Web Server
- Ruby
- Rack
- Application Server
- HTTP
- Open Source
- Open-Source
url: https://raw.githubusercontent.com/api-evangelist/puma/refs/heads/main/apis.yml
created: '2026-05-11'
modified: '2026-05-11'
specificationVersion: '0.23'
apis:
- aid: puma:control-app
  name: Puma Control/Status Application
  description: Puma ships with an optional control/status HTTP application that can be bound to a local port or Unix socket
    and queried for runtime statistics (busy threads, worker status, backlog) and lifecycle control (stop, restart, halt).
    Authentication uses a shared control token passed via the `token` query parameter.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Control
  - Status
  - Ruby
  tags_raw:
  - Control
  - Status
  - Operations
  - Ruby
  properties:
  - type: Documentation
    url: https://github.com/puma/puma/blob/master/docs/restart.md
  - type: Source Code
    url: https://github.com/puma/puma
- aid: puma:puma-gc-api
  name: Puma Gc API
  description: The Gc API from Puma — 1 operation(s) for gc.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Gc
  properties:
  - type: OpenAPI
    url: openapi/puma-gc-api-openapi.yml
- aid: puma:puma-gc-stats-api
  name: Puma Gc Stats API
  description: The Gc Stats API from Puma — 1 operation(s) for gc stats.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Gc Stats
  properties:
  - type: OpenAPI
    url: openapi/puma-gc-stats-api-openapi.yml
- aid: puma:puma-halt-api
  name: Puma Halt API
  description: The Halt API from Puma — 1 operation(s) for halt.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Halt
  properties:
  - type: OpenAPI
    url: openapi/puma-halt-api-openapi.yml
- aid: puma:puma-phased-restart-api
  name: Puma Phased Restart API
  description: The Phased Restart API from Puma — 1 operation(s) for phased restart.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Phased Restart
  properties:
  - type: OpenAPI
    url: openapi/puma-phased-restart-api-openapi.yml
- aid: puma:puma-refork-api
  name: Puma Refork API
  description: The Refork API from Puma — 1 operation(s) for refork.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Refork
  properties:
  - type: OpenAPI
    url: openapi/puma-refork-api-openapi.yml
- aid: puma:puma-reload-worker-directory-api
  name: Puma Reload Worker Directory API
  description: The Reload Worker Directory API from Puma — 1 operation(s) for reload worker directory.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Reload Worker Directory
  properties:
  - type: OpenAPI
    url: openapi/puma-reload-worker-directory-api-openapi.yml
- aid: puma:puma-restart-api
  name: Puma Restart API
  description: The Restart API from Puma — 1 operation(s) for restart.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Restart
  properties:
  - type: OpenAPI
    url: openapi/puma-restart-api-openapi.yml
- aid: puma:puma-stats-api
  name: Puma Stats API
  description: The Stats API from Puma — 1 operation(s) for stats.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Stats
  properties:
  - type: OpenAPI
    url: openapi/puma-stats-api-openapi.yml
- aid: puma:puma-stop-api
  name: Puma Stop API
  description: The Stop API from Puma — 1 operation(s) for stop.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Stop
  properties:
  - type: OpenAPI
    url: openapi/puma-stop-api-openapi.yml
- aid: puma:puma-thread-backtraces-api
  name: Puma Thread Backtraces API
  description: The Thread Backtraces API from Puma — 1 operation(s) for thread backtraces.
  humanURL: https://github.com/puma/puma/blob/master/docs/restart.md
  baseURL: http://127.0.0.1:9293
  tags:
  - Thread Backtraces
  properties:
  - type: OpenAPI
    url: openapi/puma-thread-backtraces-api-openapi.yml
common:
- type: Releases
  url: https://github.com/puma/puma/releases
- type: SecurityPolicy
  url: https://github.com/puma/puma/blob/main/SECURITY.md
- type: CodeOfConduct
  url: https://github.com/puma/puma/blob/main/CODE_OF_CONDUCT.md
- type: ContributionGuide
  url: https://github.com/puma/puma/blob/main/CONTRIBUTING.md
- type: AgenticAccess
  url: agentic-access/puma-agentic-access.yml
- type: DomainSecurity
  url: security/puma-domain-security.yml
- type: Authentication
  url: authentication/puma-authentication.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/puma
- type: Website
  url: https://puma.io
- type: Documentation
  url: https://puma.io/puma/
- type: GitHubOrganization
  url: https://github.com/puma
- type: GitHubRepository
  url: https://github.com/puma/puma
- type: RubyGems
  url: https://rubygems.org/gems/puma
- type: Issues
  url: https://github.com/puma/puma/issues
- type: Forums
  url: https://github.com/puma/puma/discussions
- type: License
  url: https://github.com/puma/puma/blob/master/LICENSE
- type: UsageTerms
  url: terms/puma-terms-of-service.yml
- type: DataLicense
  url: data-license/puma-data-license.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

Puma API — frequently asked questions

Does Puma have an API?

Yes. APIs.io lists 11 APIs from Puma, including Puma Control/Status Application, Puma Gc API and Puma Gc Stats API, and 8 more.

Is there an OpenAPI specification for the Puma API?

Yes. APIs.io indexes 10 OpenAPI specifications for Puma, each linked for download from this page.

How do I authenticate with the Puma API?

Puma uses bearer-token authentication (apiKey · 1 scheme). The details are profiled on APIs.io as Puma Authentication.

Is the Puma API ready for AI agents?

Puma has a Kin Score of 36.6 out of 100 (thin) and an Agent Readiness score of 19.2 (agent-aware), scored by API Evangelist on 2026-11-13.

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