API Usage Limits, Versioning, and Backward Compatibility

To ensure reliable performance for all customers, Bullhorn enforces several limits on API usage. These limits help balance traffic, protect system stability, and keep integrations running smoothly.

Bullhorn will reach out to the customer or partner directly if and when usage limits are being exceeded to determine the resolution.

Bullhorn reserves the right to rate limit keys that are impacting performance at any time.

API access is subject to Bullhorn's API Fair Use Policy.

API Usage Limits

These limits apply to all Bullhorn ATS editions except ATS Growth (AKA Team Edition). ATS Growth edition does not include API access.

Bullhorn monitors and limits activity in the following areas:

  • Concurrent API sessions: Maximum of 50 active sessions.

  • Total API calls per month: Up to 100,000 unless otherwise agreed upon with Bullhorn.

  • Calls per minute: Up to 1,500 requests per minute.

  • API subscriptions: Up to 50 active API subscriptions.

    • Note Time to Live (TTL) on unused subscriptions or un-retrieved subscription events is 30 days.

API usage associated with validated Bullhorn partners does not count toward your API call limits. API users created by Bullhorn Support for partner integrations also do not count against your API user limit.

API Versioning

Bullhorn continuously improves its APIs through new releases and bug fixes. Each release is identified by a version number in the web service URL, which indicates potential changes to the interface.

Examples:

  • Version 1.0: https://api.bullhornstaffing.com/webservices-1.0/?wsdl

  • Version 1.1: https://api.bullhornstaffing.com/webservices-1.1/?wsdl

A change in version number reflects a change in the API interface or functionality.

API Version Compatibility

Bullhorn maintains backward compatibility so that applications built on an existing version continue to function as long as that version remains supported.

If a change to an existing version causes unexpected behavior, Bullhorn will address it through its standard escalation and fix process.

However, applications built for one version may not automatically work with future versions. Updates to the API can introduce interface or behavior changes that require adjustments to your integration.

Recommended Version Usage

When building new integrations, always use the latest API version to ensure the longest support window and access to the newest features and fixes.

Older versions remain supported for a minimum of three years after a newer version is released.

For example, Version 1.0 will continue to be supported for at least three years after Version 1.1 becomes available.

API Version End-of-Life

When an API version approaches end-of-life (EOL):

  • Bullhorn will post an announcement on the Bullhorn Resource Center at least six months before support ends.

  • EOL will not occur sooner than three years after a version has been replaced by a newer one.

Customers are responsible for migrating their integrations before an API version becomes unsupported.

Error 429: Too Many Requests

Error 429 appears when an integration exceeds the allowed number of API calls per minute. All Bullhorn editions with API access are limited to 1,500 requests per minute to maintain fast, stable performance for all customers.

How to Resolve Error 429

  1. Wait 1 second.

  2. Try your API call again.

  3. Repeat until the call is successful or you receive a different error type.

Ensure that there are no retry limits for 429 responses, or your application may not properly recover. There is no need to throttle your own requests. Calls that are rate limited with a 429 error do not count against your limits.

FAQ

What does API mean?

API stands for Application Programming Interface.

Bullhorn APIs allow developers to integrate Bullhorn with third-party systems, customize UI elements, and send or receive data programmatically.

What are APIs used for?

API integrations allow you to:

  • Build job boards on corporate websites

  • Connect Bullhorn to payroll, back-office, operational tools, or reporting systems.

  • Integrate Bullhorn with Marketplace partner solutions

  • Perform various other use cases that involve Bullhorn ATS data

Where can I learn more about Bullhorn's API?

Customers and developers can visit our Developer Documentation for detailed guides and code samples: