Numbers API
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.
Limited machine-readable signal and partial portal coverage — documentation a human can read, but little a machine or agent can consume without scraping.
API Evangelist profiles Numbers API the way a machine reads it — 44 machine-readable artifacts across 5 APIs, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Numbers API scores 39.7/100 (thin), with a separate agent-readiness read of 32/100 (agent aware). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
Kin Score
How this is scored →scored 2026-07-27 · rubric v0.5
How we profile Numbers API
Each block below is one kind of artifact we hold for Numbers API. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 5
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
Individual APIs this provider publishes, each with its own machine-readable definition.
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.
Open Collections 1
Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.
Open, tool-agnostic API collections (OpenAPI-derived and Bruno).
Numbers API
OPEN COLLECTIONFeatures 12
The notable capabilities this provider advertises, captured as structured features so they can be searched and compared instead of read one landing page at a time.
Notable capabilities this provider offers.
Trivia Facts
Return a piece of trivia about a number, e.g. `42 is the number of little squares forming the left side trail of Microsoft's Windows 98 logo`.
Math Facts
Return a mathematical property of a number, e.g. `5 is the number of platonic solids`.
Date Facts
Return a fact about a day of the year (month/day), e.g. `February 29 is the day in 1504 that Christopher Columbus uses his knowledge of a lunar eclipse to convince Native Americ...
Year Facts
Return a fact about a year, e.g. `1969 is the year that an estimated 500 million people worldwide watch Neil Armstrong take his historic first steps on the Moon`.
Random Numbers
Use the keyword `random` in place of a number to get a random fact, optionally bounded by `min` and `max` query parameters.
JSON Responses
Append `?json` (or send `Content-Type: application/json`) to receive the fact wrapped in an object with `text`, `found`, `number`, `type`, and optional `date`/`year` fields.
Sentence Fragment Mode
Append `?fragment` to get the fact rephrased as a lowercase, no- terminal-punctuation fragment suitable for embedding in a larger sentence.
Configurable Not Found Behavior
Use `notfound=default|floor|ceil` to control what happens when no fact exists for the requested number, with an optional custom `default=...` message.
JSONP Callback
Pass `callback=functionName` to wrap the response in a JSONP function call.
Document.write Embed
Pass `write` to wrap the response in `document.write(...)`, allowing a single `