A feed is only useful when its age is clear.

Define what your feed observes

A last trade, a reference price, a candle, and an order-book level answer different questions. Record the observation type, market or asset identity, source, and unit before choosing a transport. A fast connection cannot turn one type of evidence into another.

The detailed field note uses Coinbase’s Exchange WebSocket documentation as a concrete source example. Its recommendations about clocks, recovery, and display states are a broader design framework, not an assumption that every feed uses the same sequencing rules.

REST or WebSocket?

Use a bounded request when the product needs a snapshot, a metadata lookup, or a historical range. A persistent subscription may suit a stream of changing observations. In either case, the source’s documented behavior determines what the application can safely infer.

Keep retrieval logic behind an adapter. Document requested channels, identifiers, coverage, pagination, and recovery assumptions. This makes it easier to evaluate a second source without silently changing the meaning of the displayed series.

Freshness needs its own state

Separate source event time, collector receipt time, and browser rendering time. A cache hit should preserve the original observation timestamp. A page that re-renders an old record should not show “updated now” as though new market evidence arrived.

Define a freshness budget appropriate to the use case. Show stale, incomplete, and unavailable states clearly. Connection health and data quality should be separate concepts: a socket can be open while useful observations are missing.

Build recovery before animation

Retain a checkpoint suited to the feed contract and use the documented procedure when a gap appears. Make replay idempotent so duplicate observations do not inflate volume or alter a chart. Never reconstruct missing order-book changes by guesswork.

Test late events, empty intervals, missing fields, source-time delays, and restarts. Record how derived candles handle revisions. A polished interface should reveal a coverage gap rather than quietly drawing a plausible line through it.

Static examples, honest boundaries

The examples on CryptosAPI.com are local illustrations and request objects. The site does not supply live quotes or claim measured latency, uptime, or execution quality. For an actual application, keep restricted provider credentials outside a public static website and review the intended data-use permissions.

Use the developer checklist to validate identity, timestamps, failure states, and recovery before adding a live source to your own infrastructure.