CoinMarketCap's Keyless Public API Powers Live Crypto Prices in Google Sheets

CoinMarketCap has enabled users to access live crypto prices in Google Sheets without requiring an API key or paid add-on. A custom function, built using Apps Script, makes a GET request to CoinMarketCap's Keyless Public API and returns the latest prices for a list of tickers. The function uses exponential backoff on 429 errors and retries up to four times before throwing an error.

The keyless routes used by this guide are /v3/cryptocurrency/quotes/latest, which returns full quote objects with price, percent changes, volume, and market cap, and /v1/simple/price, which returns flat id and price pairs. The function uses the former to retrieve prices for a list of tickers.

However, CoinMarketCap's API has a limitation that ticker symbols are not unique, and multiple assets can share the same symbol. To resolve this issue, the function uses the cmc_rank field to rank the candidates and keep the highest-ranked asset with a non-null cmc_rank value.