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 8 more developer resources.

📡 Source on GitHub

37.1/100 thin ▬ flat Agent 25/100 agent aware Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

AccessFreemiumSelf serve⚡ Free to try

1 APIs

Containers HPC Scientific Computing Open-Source Linux Foundation

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 37.1/100 · thin

Contract Quality 15.1 / 23

Developer Ergonomics 3.0 / 18

Access Clarity 2.8 / 18

Operational Transparency 4.6 / 12

Contract Governance 3.1 / 11

Discoverability 5.3 / 9

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

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.

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

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
  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: '2026-08-28'
  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
created: '2026-03-16'
modified: '2026-05-19'
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: 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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