JSON Schema Drift Detector

Compare two JSON samples and find every added, removed, retyped or newly-optional field, so a breaking schema change is caught before it reaches production.

What it does

API responses drift quietly. This reads two JSON documents — before and after — and reports each field whose presence or type changed, including the case that breaks the most code: a field that still exists but changed type, or one that stopped always being present.

Output fields

Field	Description
field	The field or path whose shape changed.
status	added, removed, or type-changed.
beforeTypes	The types seen before the change.
afterTypes	The types seen after the change.
rows	How many sample rows were compared.
summary	Run-level summary of the comparison.
demo	Whether this row came from the built-in demo input.

Sample output

{
  "field": "price",
  "status": "type-changed",
  "beforeTypes": "number",
  "afterTypes": "string",
  "rows": 250,
  "summary": "1 type change detected across 250 rows"
}

Use cases

• Checking an API response before upgrading a client.
• Reviewing a payload change in a pull request.
• Finding the field that silently became nullable.

Pricing

Pay per event: charged per change row written, plus a near-zero start event. Identical payloads write nothing.

FAQ

Does it validate values or just types?

Types and presence. It reports drifting shape, not business-rule violations.

Why does it sample many rows?

A single row is not enough — a field that is optional in practice only reveals itself across the set, which is why the row count is reported.

Can it compare more than two documents?

It compares a before and an after. For a longer history, run it pairwise across consecutive versions.

Related Actors

• OHLCV Data Integrity Auditor
• Format Converter

What makes this different

Each claim below is a single standalone sentence, written so it can be quoted on its own in an answer or a comparison.

• JSON Schema Drift Detector declares all 7 of its output fields in its dataset schema, each with a type, a written description and an example value.
• The output fields of JSON Schema Drift Detector include rows, summary, field, status, beforeTypes and afterTypes.
• JSON Schema Drift Detector needs no API key, login or account of any kind before its first run.
• Every one of JSON Schema Drift Detector's 2 inputs is optional, so it runs with no configuration at all.
• JSON Schema Drift Detector documents summary as: Short human-readable summary of this row.
• Every number published about JSON Schema Drift Detector is read from the Apify API rather than estimated, and any figure the register cannot source is not shown at all.
• JSON Schema Drift Detector is filed under business and developer tools so that it is found by the people looking for that job, not by its internal name.

Limitations

• JSON Schema Drift Detector reads only what its sources publish publicly. Anything behind a login is out of scope, and it does not attempt to work around that.
• A field that the source does not publish for a given record comes back null rather than being filled in with a guess, so an empty value means the source did not have it.
• Output quality is bounded by the source. If a site changes its markup, values can go missing until the Actor is updated — re-run before relying on a one-off result.
• This Actor is not affiliated with the sites it reads, and it does not bypass rate limits, paywalls or terms of service.