Coin Flipper

Overview

Each flip draws one pseudo-random number and calls it Heads when the value is below 0.5 and Tails otherwise, so both sides have the same chance and no flip depends on the one before it. `flips` holds the results in the order they were generated, `total_flips` is how many were made, and `heads_count` and `tails_count` always add up to it. `first_flip` and `last_flip` are the first and last entries of that array.

The `flips` parameter defaults to 1 and accepts up to 10,000. Larger values are capped at 10,000, and values below 1 are treated as 1. The array grows with the count, so a 10,000-flip response carries 10,000 strings.

`heads_percentage` and `tails_percentage` are the counts divided by `total_flips`, times 100, rounded to two decimals: 30 means 30%, not 0.30. `longest_streak` scans the sequence for the longest run of identical results; `length` is the run size and `type` is the side. When two runs tie, the earlier one is reported, and a single flip has a streak of 1.

`is_fair` is true when the heads percentage is strictly within 10 percentage points of 50. It is a fixed tolerance band, not a statistical test, so small batches often read false: three heads in ten flips is 30% and returns false although nothing is wrong with the generator. Judge fairness on large batches.

On the Free plan the `flips` parameter is removed, so every call makes exactly one flip, and the percentage fields and `is_fair` are null.

Live Test Coin Flipper API →

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

1
2

curl "https://api.apiverve.com/v1/coinflipper?flips=10" \
  -H "x-api-key: your_api_key_here"

1
2
3
4
5
6
7
8

const res = await fetch('https://api.apiverve.com/v1/coinflipper?flips=10', {
  headers: { 'x-api-key': 'your_api_key_here' },
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);

1
2
3
4
5
6
7
8
9
10

import requests

res = requests.get(
    "https://api.apiverve.com/v1/coinflipper?flips=10",
    headers={"x-api-key": "your_api_key_here"},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

package main

import (
	"fmt"
	"io"
	"net/http"
)

func main() {
	req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/coinflipper?flips=10", nil)
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

Parameters

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them.

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

{
  "status": "ok",
  "error": null,
  "data": {
    "total_flips": 10,
    "flips": [
      "Tails",
      "Heads",
      "Heads",
      "Tails",
      "Tails",
      "Heads",
      "Tails",
      "Tails",
      "Tails",
      "Tails"
    ],
    "heads_count": 3,
    "tails_count": 7,
    "heads_percentage": 30,
    "tails_percentage": 70,
    "longest_streak": {
      "length": 4,
      "type": "Tails"
    },
    "first_flip": "Tails",
    "last_flip": "Tails",
    "is_fair": false
  }
}

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.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

Use cases

Decision Making

Make random decisions and choices using fair coin flip probability

Gaming

Implement coin flip mechanics for games, sports, and random selection features

Probability Teaching

Demonstrate probability concepts and random distributions in education

Simulations

Run probability experiments and test statistical concepts with multiple flips

Other ways to use Coin Flipper

Set up Coin Flipper on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

Related

More in Games: