How do you get an alert when any number from a public API changes?

Guide · 17 October 2026How do you get an alert when any number from a public API changes?In short. Ask BluFabric's agent to follow the value. It dry-runs the API first so you see real numbers, then deploys a cloud workflow that checks on your schedule and alerts on a percentage move or a threshold crossing.What can I follow?Any number a public JSON API returns without an API key: a commodity price in several currencies, an exchange rate, a fund's NAV, a protocol's TVL. A monitor can combine up to four APIs, for example a gold price and an exchange-rate feed to get gold in your own currency.How do I set it up?

Ask the agent, for example "follow the gold price in USD and EUR and tell me if it moves 2%".

The agent looks at the API's response, writes the small calculation that turns it into named numbers, and does a dry run first, so you see the actual values before anything is deployed.

It then deploys the monitor with your rule: a move of a percentage (up, down or either), or a value crossing a line. A crossing alerts once each time, not on every check.

Choose how often it checks: every 5 minutes to every 24 hours.

What runs behind it?A workflow in BluFabric's cloud: Schedule → HTTP Request → Code → Change Detector → Notify. The Code block runs in a sandbox with no network or storage, so it can only do the maths on what HTTP Request fetched. You can open the workflow and edit any step, or build one like it yourself from the utility blocks.Where do the alerts go?To your BluFabric inbox, plus Telegram and push notifications if you've linked them.Questions

Can it use APIs that need a key?

Monitors use public APIs without a key. For services you've connected, such as CoinGecko or Etherscan, a workflow can read them through its connection.

How many APIs can one monitor combine?

Up to four, fetched on every check.

Will it alert me on every check?

Only when the rule is met: a move of the size you set, or a crossing, once per crossing. If you'd like a status report on every check as well, ask for it.

Logic, data and notifications blocks

Push notifications

CoinGecko integration

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Build it on the canvas, or describe it and let the agent build it.

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