Fibonacci Generator API

About the Fibonacci Generator API

The Fibonacci Generator API computes Fibonacci sequence values along with derived statistics — a sum, the trailing 5 consecutive-value ratios, and the most recent ratio as an approximation of the golden ratio. It accepts two mutually-exclusive modes: `count` for a fixed-length response, or `maxvalue` for every Fibonacci number up to a numeric ceiling. An optional `startfrom` parameter advances the generator before emission begins. All arithmetic uses standard JavaScript Number type on the server, so values above Number.MAX_SAFE_INTEGER (around the 79th Fibonacci number) cannot be represented exactly — the precision ceiling is end-to-end. The ratios array is always truncated to the last 5 entries regardless of sequence length, and each ratio is rounded to 6 decimal places.

What people use it for

Math Education

Teach Fibonacci sequences and golden ratio concepts in educational applications and tools

Algorithm Testing

Generate test data for algorithms and performance testing using Fibonacci sequences

Visual Design

Apply Fibonacci ratios and golden ratio proportions in design and layout calculations

Data Analysis

Use Fibonacci numbers in technical analysis, trading algorithms, and pattern recognition

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON

Default REST response

XML

Markup format

YAML

Human-readable

CSV

Tabular export

Beta

GraphQL

Query language

New

MCP

For AI agents

Request parameters — GET /v1/fibonaccigenerator

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

Optional

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curl "https://api.apiverve.com/v1/fibonaccigenerator?count=10&startfrom=0" \
  -H "x-api-key: YOUR_API_KEY"

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Response — GET /v1/fibonaccigenerator

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

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{
  "status": "ok",
  "error": null,
  "data": {
    "sequence": [
      0,
      1,
      1,
      2,
      3,
      5,
      8,
      13,
      21,
      34
    ],
    "count": 10,
    "start_from": 0,
    "first_value": 0,
    "last_value": 34,
    "sum": 88,
    "ratios": [
      1.666667,
      1.6,
      1.625,
      1.615385,
      1.619048
    ],
    "golden_ratio_approximation": 1.619048
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

What a call costs — 2 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Zero-code embed — one snippet, no backend

Drop an interactive Fibonacci Generator form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.

Changelog — Fibonacci Generator API

Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.

Currently v1