Simulate API degradation scenarios

Summary

This sample demonstrates how to simulate various API degradation scenarios to test how your application handles partial failures, intermittent errors, rate limiting, and slow responses. Use these configurations to build apps that gracefully degrade under stress and verify that your error handling and retry logic works before production.

Compatibility

Contributors

• Waldek Mastykarz

Version history

Version	Date	Comments
1.1	February 4, 2026	Updated to Dev Proxy v2.1.0
1.0	January 18, 2026	Initial release

Prerequisites

• Node.js LTS

Minimal path to awesome

• Get the sample:

  • Download just this sample:

    npx gitload-cli https://github.com/pnp/proxy-samples/tree/main/samples/api-degradation-scenarios

    or

  • Download as a .ZIP file and unzip it, or

  • Clone this repository

• Start the sample app and Dev Proxy by running npm start
• In a web browser, navigate to http://localhost:3000 and use the dashboard to test API degradation scenarios

Using the monitoring dashboard

The included web app provides a real-time monitoring dashboard that shows:

• Total Requests - Number of requests made
• Success Rate - Percentage of successful requests
• Average Response Time - Average response time across all requests
• Error counts - Breakdown of 503 and 429 errors
• Response Distribution - Visual bar chart of response types

Use the dashboard buttons to:

• Send Single Request - Make one API request
• Send Burst (10 requests) - Make 10 concurrent requests to trigger rate limiting
• Start Auto Requests - Continuously send requests every second
• Stop - Stop auto requests
• Clear Stats - Reset all statistics

Using Dev Proxy configurations directly

You can also run Dev Proxy with specific configurations:

All degradation scenarios combined

This configuration combines all three degradation scenarios: intermittent 503 errors (30% of requests), rate limiting (10 requests per minute), and slow responses (3-5 seconds latency).

devproxy

Intermittent 503 errors only

This configuration simulates random 503 Service Unavailable errors for 30% of requests.

devproxy --config-file .devproxy/intermittent-errors.devproxyrc.json

Rate limiting only

This configuration simulates hitting rate limits with 429 Too Many Requests responses after 10 requests per minute.

devproxy --config-file .devproxy/rate-limiting.devproxyrc.json

Slow responses only

This configuration adds random latency (3-5 seconds) to all responses.

devproxy --config-file .devproxy/slow-responses.devproxyrc.json

Features

This sample demonstrates how to use Dev Proxy to simulate API degradation scenarios. Using this sample you can:

• Test your application’s handling of intermittent 503 Service Unavailable errors
• Verify retry logic and exponential backoff implementation
• Test rate limit handling and proper use of Retry-After headers
• Measure application performance under slow network conditions
• Validate graceful degradation patterns in your application
• Demonstrate that your error handling works before deploying to production

Configuration files

File	Description
.devproxy/devproxyrc.json	Combined configuration with all degradation scenarios
.devproxy/intermittent-errors.devproxyrc.json	503 errors at 30% failure rate
.devproxy/rate-limiting.devproxyrc.json	Rate limiting at 10 requests/minute
.devproxy/slow-responses.devproxyrc.json	Random latency between 3-5 seconds
.devproxy/errors-503.json	Error responses for the GenericRandomErrorPlugin
.devproxy/mocks.json	Mock responses for successful requests
index.html	Monitoring dashboard web app
package.json	Node.js configuration to run the sample

Plugins used

• GenericRandomErrorPlugin - Simulates random errors at a configurable rate
• LatencyPlugin - Adds random delays to responses
• RateLimitingPlugin - Simulates API rate limiting behavior
• RetryAfterPlugin - Validates that clients respect Retry-After headers

Help

We do not support samples, but this community is always willing to help, and we want to improve these samples. We use GitHub to track issues, which makes it easy for community members to volunteer their time and help resolve issues.

You can try looking at issues related to this sample to see if anybody else is having the same issues.

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Disclaimer

THIS CODE IS PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.