Apptainer

Apptainer, formerly Singularity, is a Linux Foundation project providing a high-performance container runtime optimized for high-performance computing and scientific workloads. It enables reproducible, portable scientific computing with support for existing Docker/OCI containers and integration with HPC schedulers.

Apptainer publishes 2 API contracts indexed on the APIs.io network: Images API and Instances API. Tagged areas include Containers, HPC, Scientific Computing, Open Source, and Linux Foundation.

The Apptainer catalog on APIs.io includes 1 JSON-LD context and 2 Spectral governance rulesets.

Apptainer’s developer surface includes engineering blog, authentication, documentation, and 12 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

34.4/100 thin ▬ flat Agent 24/100 agent aware Front door AI 1/6 silent Heartbeat 52/100 alive Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessFreemiumSelf serve⚡ Free to try

1 published contract

Containers HPC Scientific Computing Open Source Linux Foundation

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 34.4/100 · thin

Contract Quality 11.5 / 19

Developer Ergonomics 2.9 / 15

Access Clarity 1.2 / 15

Operational Transparency 3.9 / 10

Contract Governance 2.5 / 9

Discoverability 4.3 / 8

Regulatory Posture 2.5 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 24/100 · agent aware

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 0 / 8

Request/Response Examples 7 / 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

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.

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/.

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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
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document
Delegated User Identity +6 pts — a served discovery document listing authorization_code in grant_types_supported (served), else an oauth2 authorizationCode flow or openIdConnect declared in an OpenAPI (documented)

9 more unmet checks in the Agent Readiness table above.

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

Access Clarity scores 7.9 — up to +18.4 composite points
Developer Ergonomics scores 19.0 — up to +16.2 composite points
Contract Quality scores 61.4 — up to +9.7 composite points

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.

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/apptainer/apis.yml: open an issue on github.com/api-evangelist/apptainer 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 1

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.

OpenAPI

measured — observed by APIs.io (published)

APIs 2

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

Apptainer Images API

Container image management

Apptainer Instances API

Running container instance management

Open Collections 2

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

Apptainer Container Runtime Images API

OPEN COLLECTION

Apptainer Container Runtime Images Instances API

OPEN COLLECTION

Apptainer API pricing

Not yet checked against Apptainer's own pricing page. Compiled by API Evangelist on 2026-05-04; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Free freemium	Free
Professional paid	Free
Enterprise enterprise	—

Plan details, limits and sources →

Rate limits

Free Tier Default: 10 requests per minute
Free Tier Monthly Quota: 1000 requests per month
Professional Tier Default: 100 requests per minute

Compiled by API Evangelist, not yet checked against Apptainer's documentation. All 5 limits →

Pricing Plans 1

Published pricing tiers and plan structures.

Apptainer Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Apptainer Rate Limits

5 limits

RATE LIMITS

Service Levels 1

Uptime the provider promises or reports, as SLA4OAI. Read from its own pages; APIs.io runs no monitors.

Apptainer

SLA

FinOps 1

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

Apptainer Finops

FINOPS

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Apptainer Context

12 classes · 0 properties

JSON-LD

Spectral Rules 2

Spectral governance rulesets for linting and validating these APIs.

Apptainer — jsonschema rules

5 rules · 3 warnings 2 info

SPECTRAL

Apptainer API Rules

22 rules · 8 errors 13 warnings 1 info

SPECTRAL

JSON Schema 1

Standalone JSON Schema definitions for this provider's data models.

ContainerImage

8 properties

JSON SCHEMA

JSON Structure 1

JSON Structure definitions describing this provider's data shapes.

Container Image Structure

0 properties

JSON STRUCTURE

Examples 1

Example request and response payloads for these APIs.

Container Image Example

8 fields

EXAMPLE

Security Posture 2

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

Apptainer Authentication

http · 1 scheme

SECURITY

Apptainer Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

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

Apptainer Agentic Access

5 operations · 2 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 2

SDKs, sample code, and the tooling you integrate with

CodeOfConduct

CodeOfConduct

GitHubOrg

GitHubOrg

Access & Security 3

Authentication, authorization, and security posture

SecurityPolicy

SecurityPolicy

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 3

Status, limits, changes, and where to get help

RateLimits

RateLimits

IssueTracker

IssueTracker

Releases

Releases

Commercial 2

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

Company 2

The organization behind the API

Blog

Blog

Website

Website

Source (apis.yml)

aid: apptainer
name: Apptainer
description: Apptainer, formerly Singularity, is a Linux Foundation project providing a high-performance container runtime
  optimized for high-performance computing and scientific workloads. It enables reproducible, portable scientific computing
  with support for existing Docker/OCI containers and integration with HPC schedulers.
type: Index
deliveryModel:
  model: unknown
  license_evidence:
    repo: apptainer/apptainer
    spdx: NOASSERTION
    stars: 1973
  open_source: unknown
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - openapi
  - repository-unlicensed
  generated: '2026-09-25'
  method: derived
accessModel:
  pricing: freemium
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  gated: none
  gated_source:
  - onboarding
  label: Freemium · Self-serve signup
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-11-06'
  method: derived
position: Consuming
access: 3rd-Party
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/apptainer.png
tags:
- Containers
- HPC
- Scientific Computing
- Open Source
- Linux Foundation
tags_raw:
- Containers
- HPC
- Scientific Computing
- Open Source
- Linux Foundation
- Open-Source
created: '2026-03-16'
modified: '2026-10-06'
url: https://raw.githubusercontent.com/api-evangelist/apptainer/refs/heads/main/apis.yml
specificationVersion: '0.23'
apis:
- aid: apptainer:apptainer-images-api
  name: Apptainer Images API
  description: Container image management
  humanURL: https://apptainer.org/docs/
  tags:
  - Image
  tags_raw:
  - Images
  properties:
  - type: OpenAPI
    url: openapi/apptainer-images-api-openapi.yml
  - type: Documentation
    url: https://apptainer.org/docs/
  - type: GitHubRepository
    url: https://github.com/apptainer/apptainer
  - type: JSONSchema
    url: json-schema/container-image-schema.json
  - type: JSONStructure
    url: json-structure/container-image-structure.json
  - type: Examples
    url: examples/container-image-example.json
  - type: JSONLD
    url: json-ld/apptainer-context.jsonld
  - type: SpectralRules
    url: rules/apptainer-spectral-rules.yml
  - type: Vocabulary
    url: vocabulary/apptainer-vocabulary.yaml
- aid: apptainer:apptainer-instances-api
  name: Apptainer Instances API
  description: Running container instance management
  humanURL: https://apptainer.org/docs/
  tags:
  - Instances
  properties:
  - type: OpenAPI
    url: openapi/apptainer-instances-api-openapi.yml
  - type: Documentation
    url: https://apptainer.org/docs/
  - type: GitHubRepository
    url: https://github.com/apptainer/apptainer
  - type: JSONSchema
    url: json-schema/container-image-schema.json
  - type: JSONStructure
    url: json-structure/container-image-structure.json
  - type: Examples
    url: examples/container-image-example.json
  - type: JSONLD
    url: json-ld/apptainer-context.jsonld
  - type: SpectralRules
    url: rules/apptainer-spectral-rules.yml
  - type: Vocabulary
    url: vocabulary/apptainer-vocabulary.yaml
common:
- type: Plans
  url: plans/apptainer-plans-pricing.yml
- type: RateLimits
  url: rate-limits/apptainer-rate-limits.yml
- type: FinOps
  url: finops/apptainer-finops.yml
- url: https://apptainer.org/news/
  type: Blog
- type: Website
  url: https://apptainer.org
- type: IssueTracker
  url: https://github.com/apptainer/apptainer/issues
- type: Releases
  url: https://github.com/apptainer/apptainer/releases
- type: SecurityPolicy
  url: https://github.com/apptainer/apptainer/blob/main/SECURITY.md
- type: CodeOfConduct
  url: https://github.com/apptainer/apptainer/blob/main/CODE_OF_CONDUCT.md
- type: ContributionGuide
  url: https://github.com/apptainer/apptainer/blob/main/CONTRIBUTING.md
- type: AgenticAccess
  url: agentic-access/apptainer-agentic-access.yml
- type: DomainSecurity
  url: security/apptainer-domain-security.yml
- type: Authentication
  url: authentication/apptainer-authentication.yml
- type: Documentation
  name: Apptainer Documentation
  description: Official documentation for Apptainer.
  url: https://apptainer.org/docs/
- type: GitHubOrg
  name: Apptainer GitHub
  description: Source code and repositories for Apptainer.
  url: https://github.com/apptainer
maintainers:
- FN: Kin Lane
  email: info@apievangelist.com

Apptainer API — frequently asked questions

Does Apptainer have an API?

Yes. APIs.io lists 2 APIs from Apptainer, including Apptainer Images API and Apptainer Instances API.

Is there an OpenAPI specification for the Apptainer API?

Yes. APIs.io indexes 2 OpenAPI specifications for Apptainer, each linked for download from this page.

How do I authenticate with the Apptainer API?

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

How much does the Apptainer API cost?

APIs.io lists 3 pricing plans for Apptainer, with each plan's price, limits and inclusions under Pricing on this page.

Is the Apptainer API ready for AI agents?

Apptainer has a Kin Score of 34.4 out of 100 (thin) and an Agent Readiness score of 23.7 (agent-aware), scored by API Evangelist on 2026-11-06.

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get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

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