Mastering HTTP Caching Headers for API Performance

HTTP caching is your first line of defense against unnecessary API load. Let's explore how to effectively use HTTP cache headers to improve API performance.

Essential Cache Headers

The diagram above illustrates the key components of HTTP caching. Here are the essential headers you need to know:

Cache-Control: public, max-age=3600
ETag: "33a64df551425fcc55e4d42a148795d9f25f89d4"
Last-Modified: Wed, 05 Dec 2024 14:30:00 GMT

Conditional Requests

Implement conditional requests using If-None-Match and If-Modified-Since headers:

public IActionResult Show()
{
    // Generate ETag from resource
    var etag = GenerateEtag(_resource);

    // Check if client's cached version matches
    if (Request.Headers.IfNoneMatch != etag)
    {
        return Ok(_resource);
    }

    return StatusCode(StatusCodes.Status304NotModified);
}

Remember: The best request is the one you don't have to make. Proper HTTP caching can reduce your server load by 80% or more!