Numbers API

Free REST API providing interesting mathematical facts, trivia, dates, and year facts about numbers for educational and fun applications. Returns short, readable facts about any number or date across four categories: trivia, mathematical properties, notable years, and day-of-year historical events. No authentication or API key required.

Numbers API publishes 7 APIs on the APIs.io network, including Date API, Math API, Numbers API API, and 4 more. Tagged areas include Numbers, Trivia, Math, Facts, and Education.

The Numbers API catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

Numbers API’s developer surface includes documentation, engineering blog, pricing, and 12 more developer resources.

🌐 Visit website 📡 Source on GitHub

35.0/100 thin ▬ flat Agent 26/100 agent aware saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

AccessFreeOpen⚡ Free to try

1 APIs

Numbers Trivia Math Facts Education Free No Auth

Kin Score

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

Composite quality — 35.0/100 · thin

Contract Quality 13.9 / 21

Developer Ergonomics 2.6 / 17

Access Clarity 5.8 / 17

Operational Transparency 1.5 / 11

Contract Governance 1.0 / 10

Discoverability 5.8 / 9

Regulatory Posture 3.1 / 15

Agent readiness — 26/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 9 / 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 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

Regulatory Posture applies to this provider. Its tags matched the Education & Research 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 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 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% 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/numbers-api: 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 7

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

Numbers API Date API

The Date API from Numbers API — 1 operation(s) for date.

Numbers API Math API

The Math API from Numbers API — 1 operation(s) for math.

Numbers API Numbers API API

The Numbers API API from Numbers API — 1 operation(s) for numbers api.

Numbers API Random API

The Random API from Numbers API — 4 operation(s) for random.

Numbers API Trivia API

The Trivia API from Numbers API — 1 operation(s) for trivia.

Numbers API Year API

The Year API from Numbers API — 1 operation(s) for year.

Numbers API Batch API

Multiple facts returned in a single request as a JSON map.

OPEN COLLECTION

Scroll for all 7

Pricing Plans 1

Published pricing tiers and plan structures.

Numbers Api Plans Pricing

1 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Numbers Api Rate Limits

0 limits

RATE LIMITS

FinOps 1

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

Numbers Api Finops

FINOPS

Semantic Vocabularies 1

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

Numbers Api Context

5 classes · 6 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Numbers API API Rules

4 rules · 3 warnings 1 info

SPECTRAL

JSON Schema 3

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

NumberFact

6 properties

JSON SCHEMA

BatchFacts

0 properties

JSON SCHEMA

Fact

6 properties

JSON SCHEMA

JSON Structure 2

JSON Structure definitions describing this provider's data shapes.

Numbers Batch Facts Structure

0 properties

JSON STRUCTURE

Numbers Fact Structure

6 properties

JSON STRUCTURE

4 fields

EXAMPLE

Year Fact Json

5 fields

EXAMPLE

Scroll for all 11

Security Posture 1

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

Numbers Api Domain Security

TLSv1.3 · HSTS

SECURITY

Agentic Access 1

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

Numbers Api Agentic Access

9 operations

9 operations · 0 acting

AGENTIC

Resources

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrg

GitHubOrg

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

StatusPage

StatusPage

RateLimits

RateLimits

Commercial 3

Pricing, plans, and the legal terms of use

Pricing

Pricing

Plans

Plans

FinOps

FinOps

Company 4

The organization behind the API

Website

Website

LinkedIn

Blog

Blog

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Source (apis.yml)

aid: numbers-api
name: Numbers API
description: 'Free REST API providing interesting mathematical facts, trivia, dates, and year facts about numbers for educational
  and fun applications. Returns short, readable facts about any number or date across four categories: trivia, mathematical
  properties, notable years, and day-of-year historical events. No authentication or API key required.

  '
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: free
  onboarding: open
  trial: false
  try_now: true
  public: true
  label: Free · Open access
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/numbers-api.png
url: https://raw.githubusercontent.com/api-evangelist/numbers-api/refs/heads/main/apis.yml
created: '2026-06-13'
modified: '2026-06-13'
specificationVersion: '0.23'
type: Index
tags:
- Numbers
- Trivia
- Math
- Facts
- Education
- Free
- No Auth
apis:
- aid: numbers-api:numbers-api-date-api
  name: Numbers API Date API
  description: The Date API from Numbers API — 1 operation(s) for date.
  humanURL: http://numbersapi.com
  baseURL: http://numbersapi.com
  tags:
  - Date
  properties:
  - type: OpenAPI
    url: openapi/numbers-api-date-api-openapi.yml
  - type: Documentation
    url: http://numbersapi.com/#42
- aid: numbers-api:numbers-api-math-api
  name: Numbers API Math API
  description: The Math API from Numbers API — 1 operation(s) for math.
  humanURL: http://numbersapi.com
  baseURL: http://numbersapi.com
  tags:
  - Math
  properties:
  - type: OpenAPI
    url: openapi/numbers-api-math-api-openapi.yml
  - type: Documentation
    url: http://numbersapi.com/#42
- aid: numbers-api:numbers-api-numbers-api-api
  name: Numbers API Numbers API API
  description: The Numbers API API from Numbers API — 1 operation(s) for numbers api.
  humanURL: http://numbersapi.com
  baseURL: http://numbersapi.com
  tags:
  - Numbers API
  properties:
  - type: OpenAPI
    url: openapi/numbers-api-numbers-api-api-openapi.yml
  - type: Documentation
    url: http://numbersapi.com/#42
- aid: numbers-api:numbers-api-random-api
  name: Numbers API Random API
  description: The Random API from Numbers API — 4 operation(s) for random.
  humanURL: http://numbersapi.com
  baseURL: http://numbersapi.com
  tags:
  - Random
  properties:
  - type: OpenAPI
    url: openapi/numbers-api-random-api-openapi.yml
  - type: Documentation
    url: http://numbersapi.com/#42
- aid: numbers-api:numbers-api-trivia-api
  name: Numbers API Trivia API
  description: The Trivia API from Numbers API — 1 operation(s) for trivia.
  humanURL: http://numbersapi.com
  baseURL: http://numbersapi.com
  tags:
  - Trivia
  properties:
  - type: OpenAPI
    url: openapi/numbers-api-trivia-api-openapi.yml
  - type: Documentation
    url: http://numbersapi.com/#42
- aid: numbers-api:numbers-api-year-api
  name: Numbers API Year API
  description: The Year API from Numbers API — 1 operation(s) for year.
  humanURL: http://numbersapi.com
  baseURL: http://numbersapi.com
  tags:
  - Year
  properties:
  - type: OpenAPI
    url: openapi/numbers-api-year-api-openapi.yml
  - type: Documentation
    url: http://numbersapi.com/#42
- aid: numbers-api:numbers-batch-api
  name: Numbers API Batch API
  description: Multiple facts returned in a single request as a JSON map.
  humanURL: http://numbersapi.com/
  baseURL: http://numbersapi.com/
  tags:
  - Batch
  properties:
  - type: OpenAPI
    url: openapi/numbers-batch-api-openapi.yml
  - type: Documentation
    url: http://numbersapi.com/#api
  - type: APIReference
    url: http://numbersapi.com/#api
  - type: GettingStarted
    url: http://numbersapi.com/#api
  - type: JSONSchema
    url: json-schema/numbers-fact-schema.json
  - type: JSONSchema
    url: json-schema/numbers-batch-facts-schema.json
  - type: JSONStructure
    url: json-structure/numbers-fact-structure.json
  - type: JSONStructure
    url: json-structure/numbers-batch-facts-structure.json
  - type: Examples
    url: examples/numbers-fact-example.json
  - type: Examples
    url: examples/numbers-trivia-fact-example.json
  - type: Examples
    url: examples/numbers-math-fact-example.json
  - type: Examples
    url: examples/numbers-date-fact-example.json
  - type: Examples
    url: examples/numbers-year-fact-example.json
  - type: Examples
    url: examples/numbers-batch-facts-example.json
common:
- type: AgenticAccess
  url: agentic-access/numbers-api-agentic-access.yml
- type: DomainSecurity
  url: security/numbers-api-domain-security.yml
- type: Website
  url: http://numbersapi.com
- type: Documentation
  url: http://numbersapi.com/#42
- type: GitHubOrg
  url: https://github.com/divad12
- type: LinkedIn
  url: https://www.linkedin.com/in/davidhu2000/
- type: Blog
  url: http://numbersapi.com
- type: Pricing
  url: http://numbersapi.com
- type: StatusPage
  url: http://numbersapi.com
- type: X
  url: https://x.com/numbersapi
- type: Plans
  url: plans/numbers-api-plans-pricing.yml
- type: RateLimits
  url: rate-limits/numbers-api-rate-limits.yml
- type: FinOps
  url: finops/numbers-api-finops.yml
- type: Documentation
  url: http://numbersapi.com/#api
- type: Blog
  url: http://david-hu.com/2012/03/05/announcing-numbers-api.html
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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