Response Compression

Response compression settings for reducing HTTP response sizes using Brotli and Gzip algorithms.

Overview

json

{
  "ResponseCompression": {
    "Enabled": false,
    "EnableForHttps": false,
    "UseBrotli": true,
    "UseGzipFallback": true,
    "CompressionLevel": "Optimal",
    "IncludeMimeTypes": [
      "text/plain",
      "text/css",
      "application/javascript",
      "text/javascript",
      "text/html",
      "application/xml",
      "text/xml",
      "application/json",
      "text/json",
      "image/svg+xml",
      "font/woff",
      "font/woff2",
      "application/font-woff",
      "application/font-woff2"
    ],
    "ExcludeMimeTypes": []
  }
}

Settings Reference

Setting	Type	Default	Description
Enabled	bool	false	Enable response compression for HTTP responses.
EnableForHttps	bool	false	Enable response compression for HTTPS responses.
UseBrotli	bool	true	Use Brotli compression algorithm when supported by client.
UseGzipFallback	bool	true	Use Gzip compression as fallback when Brotli is not supported.
CompressionLevel	string	"Optimal"	Compression level: Optimal, Fastest, NoCompression, SmallestSize.
IncludeMimeTypes	array	(see below)	MIME types to include for compression.
ExcludeMimeTypes	array	[]	MIME types to exclude from compression.

Compression Levels

Level	Description
Optimal	Balance between compression ratio and speed (default).
Fastest	Fastest compression with lower compression ratio.
SmallestSize	Best compression ratio but slower.
NoCompression	No compression applied.

Compression Algorithms

Brotli

Brotli provides better compression ratios than Gzip, especially for text content. When UseBrotli is true, the server will use Brotli compression if the client supports it (indicated by Accept-Encoding: br header).

Gzip Fallback

When UseGzipFallback is true, the server falls back to Gzip compression for clients that don't support Brotli but do support Gzip (indicated by Accept-Encoding: gzip header).

HTTPS Compression

Security Consideration

Enabling compression for HTTPS responses (EnableForHttps: true) may expose your application to BREACH-style attacks. Only enable if you understand the security implications and have appropriate mitigations in place.

Default MIME Types

The default IncludeMimeTypes covers common compressible content:

Category	MIME Types
Text	text/plain, text/css, text/html
JavaScript	application/javascript
XML	application/xml, text/xml
JSON	application/json, text/json
SVG	image/svg+xml
Fonts	font/woff, font/woff2, application/font-woff, application/font-woff2

Example Configuration

Enable compression for production:

json

{
  "ResponseCompression": {
    "Enabled": true,
    "EnableForHttps": true,
    "UseBrotli": true,
    "UseGzipFallback": true,
    "CompressionLevel": "Optimal"
  }
}

High-compression configuration for bandwidth-constrained environments:

json

{
  "ResponseCompression": {
    "Enabled": true,
    "EnableForHttps": true,
    "UseBrotli": true,
    "UseGzipFallback": true,
    "CompressionLevel": "SmallestSize"
  }
}

Related

• Comment Annotations Guide - How annotations work
• Configuration Guide - How configuration works

Next Steps

• Server & SSL - Configure HTTPS and Kestrel web server
• Logging - Configure logging outputs