> ## Documentation Index
> Fetch the complete documentation index at: https://docs.stackone.com/llms.txt
> Use this file to discover all available pages before exploring further.

# StackOne Identifiers

> Understand synthetic IDs and how to use them interchangeably with provider IDs

# Understanding Synthetic IDs in Our API

We often need to combine data from multiple sources to create unified responses. For instance, consider Workday's Applications. To create a unified application with the data provided by Workday, we need to link Job Requisitions with Candidates. Here, a candidate can be associated with multiple job requisitions and vice versa. Consequently, we can't use either of these IDs to identify a specific record.

## What Are Synthetic IDs?

To address this, we've introduced the concept of synthetic IDs. These IDs do not match an ID in the underlying provider, but allow you (and us) to identify the combined resources that were used to create this unified response. You can then use these IDs across our unified API. For example, you could use a `job_id` from a listing to search for candidates matching that value.

For simplicity, all IDs provided by the API will be synthetic IDs. These IDs are easy to identify because they are prefixed with `c28xIQ`. In most cases, you'll still be able to see the underlying ID from the provider in a field prefixed by `remote_`. For example, in the case of `job_id`, the underlying ID will be in `remote_job_id`.

## Using Synthetic and Regular IDs

When it comes to writing or fetching data, both types of IDs can be used interchangeably.

### Fetching Data

For reading, let's say we have the synthetic and regular IDs:

```jsx theme={null}
{
  job_id: 'c28xIQaWQ6MQ',
  remote_id: '1'
}

```

You can make either of these calls and expect the same response:

```bash theme={null}
# Using a regular ID
curl --request GET \
--url https://api.stackone.com/unified/ats/jobs/1 \
--header 'accept: application/json'

# Using a synthetic ID
curl --request GET \
--url https://api.stackone.com/unified/ats/jobs/c28xIQaWQ6MQ \
--header 'accept: application/json'

```

This applies to any query parameters as well:

```bash theme={null}
# Using a regular ID
curl --request GET \
     --url https://api.stackone.com/unified/ats/applications?raw=false&filter[job_id]=1&page_size=25 \
     --header 'accept: application/json'

# Using a synthetic ID
curl --request GET \
     --url https://api.stackone.com/unified/ats/applications?raw=false&filter[job_id]=c28xIQaWQ6MQ&page_size=25 \
     --header 'accept: application/json'

```

### Writing Data

When it comes to writing, the behavior is similar. You can use the ID field as usual and provide either a regular ID or a synthetic ID: