CoinGecko API

Info Crypto uses the CoinGecko public API as its primary data source. It powers the Home page market overview, the Converter page live prices, and the Charts page historical data — all without requiring an API key.

The CoinGecko free tier enforces a rate limit of 30 calls per minute. The app uses localStorage caching with a 5-minute TTL to stay well within this limit under normal usage, but heavy manual refreshing can still trigger 429 responses.

No API key is required for the public demo endpoints used in this project. If you deploy to production and need higher throughput, consider upgrading to a CoinGecko paid plan and adding an x-cg-demo-api-key header to each request.

Endpoints

GET /coins/markets
GET /simple/price
GET /coins/{id}/market_chart

Top cryptocurrencies by market cap

Returns a ranked list of coins ordered by market capitalisation. Used by the Home page to display the top 20 cryptocurrencies.Source file: src/services/cryptoApi.js — getTopCryptos()

GET https://api.coingecko.com/api/v3/coins/markets?vs_currency=usd&order=market_cap_desc&per_page=20&page=1

Query parameters

query.vs_currency

string

default:"usd"

required

The target currency for all price and market cap values. Set to usd.

query.order

string

default:"market_cap_desc"

Sort order for results. market_cap_desc returns coins from largest to smallest market cap.

query.per_page

number

default:"20"

Number of coins returned per page. Fixed at 20 in this integration.

query.page

number

default:"1"

Page number for pagination. Fixed at 1 — only the first page is fetched.

Source code

src/services/cryptoApi.js

export async function getTopCryptos() {
  try {
    const response = await fetch(
      "https://api.coingecko.com/api/v3/coins/markets?vs_currency=usd&order=market_cap_desc&per_page=20&page=1"
    );
    const data = await response.json();
    return data;
  } catch (error) {
    console.error("Error fetching cryptos:", error);
    throw error;
  }
}

Cache key

Key	TTL
`getInfoCrypto`	5 minutes

The cache helper keepInfo() in src/services/cache.js reads getInfoCrypto from localStorage and skips the network request if the cached value is less than 5 minutes old.

Response shape

Returns an array of coin objects.

[]\.id

string

required

Unique CoinGecko coin identifier (e.g. "bitcoin").

[]\.symbol

string

required

Ticker symbol in lowercase (e.g. "btc").

[]\.name

string

required

Human-readable coin name (e.g. "Bitcoin").

[]\.image

string

required

URL to the coin logo image.

[]\.current_price

number

required

Current price in USD.

[]\.market_cap

number

required

Total market capitalisation in USD.

[]\.total_volume

number

required

24-hour trading volume in USD.

[]\.price_change_percentage_24h

number

required

Percentage price change over the last 24 hours. Negative values indicate a decline.

Example response

[
  {
    "id": "bitcoin",
    "symbol": "btc",
    "name": "Bitcoin",
    "image": "https://assets.coingecko.com/coins/images/1/large/bitcoin.png",
    "current_price": 67423.00,
    "market_cap": 1327000000000,
    "total_volume": 28500000000,
    "price_change_percentage_24h": 2.34
  }
]

Spot prices for converter

Returns the current USD price for a fixed set of coins. Used by the Converter page to power currency conversion calculations.Source file: src/services/priceApi.js — priceApi()

GET https://api.coingecko.com/api/v3/simple/price?ids=usd,bitcoin,ethereum,solana,cardano,tether,binancecoin&vs_currencies=usd

Query parameters

query.ids

string

required

Comma-separated list of CoinGecko coin IDs to fetch prices for. The integration requests: usd, bitcoin, ethereum, solana, cardano, tether, binancecoin.

query.vs_currencies

string

default:"usd"

required

Target currency for all returned prices. Set to usd.

Source code

src/services/priceApi.js

export async function priceApi() {
  try {
    const response = await fetch(
      "https://api.coingecko.com/api/v3/simple/price?ids=usd,bitcoin,ethereum,solana,cardano,tether,binancecoin&vs_currencies=usd"
    );
    if (!response.ok) {
      throw new Error(`News request failed with status ${response.status}`);
    }
    const data = await response.json();
    return data;
  } catch (error) {
    console.error("Error fetching price:", error);
    throw error;
  }
}

Cache key

Key	TTL
`getPriceCrypto`	5 minutes

The cache helper keepPrice() in src/services/cache.js checks getPriceCrypto in localStorage before making a network request.

Response shape

Returns an object keyed by coin ID. Each value is an object with a usd price field.

{coinId}

object

required

Top-level key is a CoinGecko coin ID (e.g. bitcoin).

Show properties

usd

number

required

Current price of the coin in USD.

Example response

{
  "bitcoin": { "usd": 67423.00 },
  "ethereum": { "usd": 3512.45 },
  "solana": { "usd": 172.88 },
  "cardano": { "usd": 0.452 },
  "tether": { "usd": 1.00 },
  "binancecoin": { "usd": 594.21 }
}

Historical price chart data

Returns time-series price data for a single coin over a specified number of days. Used by the Charts page to render price history graphs.Source file: src/services/historyApi.js — getHistoryCrypto()

GET https://api.coingecko.com/api/v3/coins/{cryptoId}/market_chart?vs_currency=usd&days={days}

Path parameters

path.cryptoId

string

required

CoinGecko coin ID for the coin to retrieve history for (e.g. bitcoin, ethereum).

Query parameters

query.vs_currency

string

default:"usd"

required

Target currency for price values. Set to usd.

query.days

number

required

Number of days of historical data to return. Passed in by the Charts page (e.g. 1, 7, 30, 365).

Source code

src/services/historyApi.js

export async function getHistoryCrypto({ cryptoId, days }) {
  try {
    const response = await fetch(
      `https://api.coingecko.com/api/v3/coins/${cryptoId}/market_chart?vs_currency=usd&days=${days}`
    );
    const data = await response.json();
    return data;
  } catch (error) {
    console.error("Error fetching history:", error);
    throw error;
  }
}

Cache key

Key	TTL
`history_${cryptoId}_${days}`	5 minutes

Each unique combination of cryptoId and days gets its own localStorage entry. For example, 7-day Bitcoin history is cached under history_bitcoin_7.

Response shape

prices

array

required

Array of [timestamp, price] tuples representing the price at each data point.

Show properties

[][0]

number

required

Unix timestamp in milliseconds.

[][1]

number

required

Price in USD at that timestamp.

Example response

{
  "prices": [
    [1713744000000, 63821.45],
    [1713747600000, 64102.10],
    [1713751200000, 63987.22]
  ]
}

Caching strategy

All CoinGecko calls are wrapped in cache helpers defined in src/services/cache.js. Each helper reads from localStorage first and only makes a network request when the cached value is missing or older than 5 minutes.

src/services/cache.js

export async function keepInfo() {
  const cache = localStorage.getItem("getInfoCrypto");
  const cacheDate = localStorage.getItem("getInfoCryptoDate");

  if (cache && cacheDate && Date.now() - Number(cacheDate) < 5 * 60 * 1000) {
    return JSON.parse(cache);
  } else {
    const data = await getTopCryptos();
    localStorage.setItem("getInfoCrypto", JSON.stringify(data));
    localStorage.setItem("getInfoCryptoDate", Date.now());
    return data;
  }
}

The same pattern is used by keepPrice() and keepHistory() for the other two endpoints.

Cache helper	localStorage key	Endpoint
`keepInfo()`	`getInfoCrypto`	`/coins/markets`
`keepPrice()`	`getPriceCrypto`	`/simple/price`
`keepHistory(cryptoId, days)`	`history_${cryptoId}_${days}`	`/coins/{id}/market_chart`

Get Started

Features

Architecture

API Integrations

Development

Endpoints

Top cryptocurrencies by market cap

Query parameters

Source code

Cache key

Response shape

Example response

Spot prices for converter

Query parameters

Source code

Cache key

Response shape

Example response

Historical price chart data

Path parameters

Query parameters

Source code

Cache key

Response shape

Example response

Caching strategy

Build docs developers (and LLMs) love

Get Started

Features

Architecture

API Integrations

Development

​Endpoints

​Top cryptocurrencies by market cap

​Query parameters

​Source code

​Cache key

​Response shape

​Example response

​Spot prices for converter

​Query parameters

​Source code

​Cache key

​Response shape

​Example response

​Historical price chart data

​Path parameters

​Query parameters

​Source code

​Cache key

​Response shape

​Example response

​Caching strategy

Build docs developers (and LLMs) love

Endpoints

Top cryptocurrencies by market cap

Query parameters

Source code

Cache key

Response shape

Example response

Spot prices for converter

Query parameters

Source code

Cache key

Response shape

Example response

Historical price chart data

Path parameters

Query parameters

Source code

Cache key

Response shape

Example response

Caching strategy