Build a Scheduled Crypto Price Monitor with CoinGecko

A useful price monitor is more than a frequent request. It needs a stable asset list, successful-run checks, timestamped storage, threshold logic, and protection against missing data. The CoinGecko Markets Scraper handles the collection layer.

Freeze the monitored basket

Choose explicit CoinGecko IDs so an asset cannot enter or leave the monitor merely because its market rank changed.

{
  "coinIds": ["bitcoin", "ethereum", "solana"],
  "vsCurrency": "usd",
  "maxResults": 3
}

Run this input once and verify three rows with current timestamps. Save it as an Apify Task, then select an interval that fits the upstream allowance. A Demo key is appropriate when a sustained schedule exceeds keyless capacity.

Alert only on valid snapshots

Before calculating movement, require a successful run, the expected number of unique IDs, non-null prices, the requested currency, and a recent last_updated value. If one asset is missing, flag the snapshot as incomplete instead of treating its price as zero.

Store each row with the Actor run time. Compare the latest valid snapshot with the prior valid snapshot for the same coin and currency. Thresholds can use absolute change, percentage change, market-cap movement, or volume. Add a cooldown so the same condition does not notify every interval.

The source's price_change_percentage_24h answers a different question from the change between your own snapshots. Keep both metrics clearly named. Route notifications through an Apify webhook, automation platform, or your application, and include the coin ID, two timestamps, values, threshold, and source URL so recipients can verify what triggered the alert.