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 APIs 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 authentication, documentation, and 9 more developer resources.

🌐 Visit website 📡 Source on GitHub

35.4/100 thin ▬ flat Agent 25/100 agent aware Front door AI 1/6 silent Full breakdown ↓
scored 2026-09-25 · rubric v0.23.0

AccessFreemiumSelf serve⚡ Free to try

1 APIs

Containers HPC Scientific Computing Open Source Linux Foundation

Kin Score

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

Composite quality — 35.4/100 · thin

Contract Quality 11.5 / 19

Developer Ergonomics 2.5 / 15

Access Clarity 2.4 / 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 — 25/100 · 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

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/apptainer: 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 →

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 3

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

API Collection

OPEN COLLECTION

Apptainer Container Runtime Images API

OPEN COLLECTION

Apptainer Container Runtime Images Instances API

OPEN COLLECTION

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

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 API 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 2

Status, limits, changes, and where to get help

IssueTracker

IssueTracker

Releases

Releases

Company 1

The organization behind the API

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
  label: Freemium · Self-serve signup
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-09-03'
  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: '2026-09-16'
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: 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

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