ServiceNow REST Api Rate Limit

In ServiceNow, rate limits help manage the volume of incoming REST API requests and protect system performance by preventing excessive API traffic. Setting up rate limits ensures that your instance stays responsive and stable, even when external systems are making frequent calls. Let’s go through how to create and manage rate limits in ServiceNow.

1. Where to Create Rate Limits:
You define rate limits in the “System Web Services > REST > Rate Limit Rules” module.

2. Steps to Create a Rate Limit:
Here’s a step-by-step guide:

• Navigate to Rate Limits: Go to System Web Services > REST > Rate Limits > Create New.
• Name: Give the rate limit a clear and descriptive name.
• REST API: Choose the API namespace you want to limit (like Table API, Attachment API, or your own scripted APIs).
• Threshold per hour: Set the maximum number of requests allowed within a specified time period.
• Status: Make sure the rate limit is active.
• Apply to: Chose one from All users , Single User, User with role

3. Example:
Let’s say you want to limit requests to the Table API to 1000 requests per hour per user:

• Name: Table API User Rate Limit
• REST API : Table API
• Apply to: All users
• Threshold per hour: 1000

4. Handling Rate Limit Exceeding:
When an API client exceeds the rate limit, ServiceNow responds with an HTTP 429 Too Many Requests status code. You can customize error handling and response messages if needed.

5. Advanced Considerations:

• Scoped Applications: Ensure you’re applying rate limits only to the APIs you own in your scoped app.

An example with screenshots.

1. Create a new Record [ System Web Services > REST > Rate Limit Rules ]

In image above, we have created a rate limite rule to limit POST calls to Case table to 3 calls per hour. We have applied this rule to All users for demo purpose, you should chose Single user or User with role with create a more granular rules.

2. Call this API four times We will now use curl to call this API 4 times.

That’s it folks.