# JSON Schema Drift Detector — Catch Breaking Changes (`alaudinburki/json-schema-drift`) Actor

Compare two JSON datasets and identify added, removed and changed field types.

- **URL**: https://apify.com/alaudinburki/json-schema-drift.md
- **Developed by:** [alaudin burki](https://apify.com/alaudinburki) (community)
- **Categories:** Business, Developer tools
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $3.00 / 1,000 results

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.

Learn more: https://docs.apify.com/actors/running/actors-in-store.md#pay-per-event

## What's an Apify Actor?

An Actor is a serverless cloud program that runs on the Apify platform. It has two run modes.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.

Apify vocabulary and the platform model are defined once, in the agent quickstart at https://apify.com/agents.md.

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.

Do not guess an integration path. Every one of them is in the agent quickstart at https://apify.com/agents.md: the Apify MCP server, Agent Skills with the Apify CLI, the JavaScript and Python clients, the REST API, and the account-free path for an agent with no human to sign in. It also carries the rule on stating cost before the first paid run.

For examples already wired to this Actor's own input schema, see the [API](#api) section below.

Each client library has reference documentation the quickstart does not restate: [JavaScript/TypeScript](https://docs.apify.com/api/client/js/docs.md) (`npm install apify-client`) and [Python](https://docs.apify.com/api/client/python/docs.md) (`pip install apify-client`).

# README

## 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

```json
{
  "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.

# Actor input Schema

## `rows` (type: `array`):

JSON rows to analyze. Use the example in the README for required fields.

## `datasetId` (type: `string`):

Optional Apify dataset ID used instead of inline rows.

## Actor input object example

```json
{
  "rows": [
    {
      "version": "before",
      "data": {
        "id": 1,
        "price": 10
      }
    },
    {
      "version": "after",
      "data": {
        "id": 1,
        "price": "10.00",
        "currency": "USD"
      }
    }
  ]
}
```

# Actor output Schema

## `results` (type: `string`):

Analysis output rows.

## `summary` (type: `string`):

Counts and totals for the analysis.

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
const input = {
    "rows": [
        {
            "version": "before",
            "data": {
                "id": 1,
                "price": 10
            }
        },
        {
            "version": "after",
            "data": {
                "id": 1,
                "price": "10.00",
                "currency": "USD"
            }
        }
    ]
};

// Run the Actor and wait for it to finish
const run = await client.actor("alaudinburki/json-schema-drift").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_input = { "rows": [
        {
            "version": "before",
            "data": {
                "id": 1,
                "price": 10,
            },
        },
        {
            "version": "after",
            "data": {
                "id": 1,
                "price": "10.00",
                "currency": "USD",
            },
        },
    ] }

# Run the Actor and wait for it to finish
run = client.actor("alaudinburki/json-schema-drift").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print(f"💾 Check your data here: https://console.apify.com/storage/datasets/{run.default_dataset_id}")
for item in client.dataset(run.default_dataset_id).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{
  "rows": [
    {
      "version": "before",
      "data": {
        "id": 1,
        "price": 10
      }
    },
    {
      "version": "after",
      "data": {
        "id": 1,
        "price": "10.00",
        "currency": "USD"
      }
    }
  ]
}' |
apify call alaudinburki/json-schema-drift --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,alaudinburki/json-schema-drift"
        }
    }
}
```

The hosted server signs you in with OAuth on first connect, so no API token belongs in this config. Clients without OAuth support can send an `Authorization: Bearer <APIFY_API_TOKEN>` header instead, using a token from API & Integrations in Apify Console (https://console.apify.com/settings/integrations).

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/nDVd3PcPHgaC8EkIE/builds/YFcAAURxgbPDKPIia/openapi.json