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Rate limiting helps ensure platform stability, fairness, and consistent performance for all users.
DeBounce applies limits depending on the type of API key and the operation being performed.

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Regular API Key

All requests made with a regular (private) API key are subject to concurrency limits.
These limits prevent overload and help ensure fast, reliable validation results.

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Concurrent Request Limit

  • You may send up to 5 concurrent API calls at a time.
  • If the data enrichment option is enabled, the limit becomes 2 concurrent calls.
If your application exceeds this limit, the API returns: 
HTTP/429 Too Many Requests
{
  "debounce": {
    "error": "Maximum concurrent calls reached",
    "code": "0"
  },
  "success": "0"
}

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Recommendations for Developers

  • Use connection pooling or queueing to control concurrency
  • Retry failed requests with backoff timing
  • Cache results when possible
  • Avoid validating large volumes in parallel without a queue
These practices improve performance and help remain within platform limits.
Need more validation throughput? Contact our team to request upgraded rate limits.

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Public API Key (Client-Side Use)

A public API key starts with public_ and is intended for JavaScript usage, such as real-time form validation widgets.

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CORS Requirements

You must add your domain to the key’s approved CORS domain list.

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Daily Per-IP Limit

To protect your account from abuse, each internet IP address may validate up to:
  • 20 emails per day
If a user exceeds this limit, the widget displays “You performed many validations”, and the API returns: 
HTTP/429 Too Many Requests
{
  "debounce": {
    "error": "Authentication Failed - The maximum number of calls per day reached."
  },
  "success": "0"
}
You can check your current public IP address using:
WhatIsMyIP

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Bulk Validation Limits

Bulk validation jobs are intentionally serialized to ensure system stability.

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Bulk API Rules

  • Only one active bulk validation job is allowed per account
  • Additional uploads or API bulk jobs are queued automatically
  • When the active job finishes, the next queued job begins
This guarantees predictable processing and prevents overload for large lists.