# Numbers API

**Canonical:** https://apis.io/providers/numbers/  
**Website:** http://numbersapi.com/  
**APIs profiled:** 5

Numbers API by David Hu and Mack Duan — a free, community-contributed HTTP API for interesting facts about numbers. Returns trivia, math, date, and year facts as plain text or JSON. Supports random numbers, ranges/batches, JSONP callbacks, document.write embedding, sentence-fragment responses, and configurable not-found behavior.

## Kin Score — 29.1 / 100 (thin)

Scored 2026-08-21 under rubric 0.12.0. Trend: flat (+0.4 from 28.7).

| Facet | Score |
|---|---|
| Discoverability | 81.5 |
| Contract Quality | 65.2 |
| Governance | 28.8 |
| Contract Governance | 28.8 |
| Operational Transparency | 0.0 |
| Developer Ergonomics | 6.0 |
| Commercial Clarity | 0.0 |
| Access Clarity | 0.0 |

## Agent readiness — 28.1 (agent-aware)

| Dimension | Value |
|---|---|
| Spec Presence | yes |
| Agentic Access | derived |
| Reversibility Documented | na |
| MCP Server | no |
| Auth Clarity | no |
| Idempotency | na |
| Error Semantics | no |
| OpenAPI Examples | verified |
| Rate Limit Signal | no |
| Event Surface Described | no |
| Agent Skills | no |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | na |

## Access

Unknown — onboarding: unknown, pricing: unknown, trial: no (confidence: low).

## APIs (5)

- **Numbers API Batch API** — Multiple facts returned in a single request as a JSON map.
- **Numbers API Date API** — Historical facts associated with a day of the year.
- **Numbers API Math API** — Mathematical properties of integers.
- **Numbers API Trivia API** — Trivia facts about integers.
- **Numbers API Year API** — Historical facts associated with a year.

## Agentic access (1)

- **Numbers Agentic Access** — 10 operations

## Security (1)

- **Numbers Domain Security** — TLSv1.3 · HSTS

## Use cases (6)

- **Engagement Copy** — Insert living facts into marketing copy or dashboards, e.g. `We now have more users than the number of times Julius Caesar was stabbed`.
- **Calendar Widgets** — Pair `month/day/date` with a date picker or daily widget to surface a historical fact for the current day.
- **Anniversary and Year-in-Review** — Use `/{year}/year` to enrich anniversary, retrospective, and year-in-review content with curated facts.
- **Daily Random Trivia** — Power "fact of the day" features for chatbots, newsletters, screen savers, and home assistants using `/random/trivia`.
- **Math Education** — Surface mathematical properties of numbers in educational tools and worksheets via `/{n}/math`.
- **Mock and Demo Data** — Provide free, unauthenticated, low-latency text responses ideal for tutorials, demos, and beginner HTTP client exercises.

## Tags

Science And Math, Public APIs, Trivia, Numbers, Dates, Open-Source

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/numbers/). Scores are computed from the provider's own public artifacts under a published rubric.