Stream a JSON reply and show each field the moment it lands

Users stare at a blank spinner for seconds while the whole structured reply finishes, when half the fields were ready much sooner.

Intermediate to advancedRead 7 minDoing: an afternoon8 steps

▶ Start

What you'll have at the end

A streaming handler where four fields of one structured reply each appear on screen exactly once, fully formed, at the instant their value in the buffer stops changing, with a run that proves none of them ever showed a wrong or half-typed value on the way there.

Before you start

You need

A JSON schema with several top-level fields, already wired into a streaming LLM call that returns replies validated against it.

Not covered

Deciding whether a field that is itself a list of several items should show one item at a time: this recipe only covers flat, top-level fields, each landing once.

Leans on

8 steps

Where to go next

Turn a chatty reply into one clean JSON object

your replies are not reliably landing as clean JSON in the first place, which this recipe assumes is already true before streaming any of it makes sense.

Checked 15 Aug 2026

Part of the Structured Output Generation with LLMs cookbook