Using a CDN and Caching for Web Games
For web games, delivery speed directly affects the player experience. A game that takes eight seconds to load loses most of its potential players before they see the title screen. A CDN addresses this by caching your JavaScript bundles, WebAssembly modules, textures, and audio files at hundreds of edge locations worldwide, ensuring that a player in Tokyo loads the same game just as fast as a player in New York. The following steps walk you through configuring a CDN specifically for web game delivery, with attention to the caching and compression patterns that matter most for game assets.
Choose and Configure a CDN Provider
The three most common CDN choices for web game hosting are Amazon CloudFront, Cloudflare, and Fastly. CloudFront integrates directly with S3, making it the natural choice if your game files are already in an S3 bucket. Cloudflare offers a generous free tier with unlimited bandwidth and includes DDoS protection and automatic SSL, making it an excellent choice for indie developers on a budget. Fastly provides the most granular caching control but is more expensive and geared toward teams with specific edge computing needs.
To set up CloudFront, create a new distribution in the AWS console and specify your S3 bucket or web server as the origin. Set the viewer protocol policy to "Redirect HTTP to HTTPS" so all traffic is encrypted. Enable the "Compress objects automatically" option to turn on both gzip and Brotli compression. Choose the price class that matches your audience's geography. The "Use All Edge Locations" option gives the best global performance but costs slightly more per request than regional options.
For Cloudflare, the setup is even simpler. Add your domain to Cloudflare, update your domain's nameservers to point to Cloudflare's nameservers, and the CDN activates automatically. Cloudflare proxies all traffic through its network by default, providing caching, compression, and SSL without any additional configuration. You can fine-tune caching behavior through Page Rules or the newer Cache Rules interface.
Set Up Content-Based Cache Keys
The most important caching technique for web games is content-based cache keys, also called cache busting through filename hashing. When your build tool processes your game, it appends a hash of the file contents to the filename, so game.js becomes game.a3f8b2c1.js. Because the hash changes whenever the file content changes, you can safely cache these files for extremely long periods (a year or more) without worrying about players receiving stale versions.
Configure your CDN to set a Cache-Control: max-age=31536000, immutable header for all files with content hashes in their names. The immutable directive tells the browser not to revalidate the file even during a hard refresh, which eliminates unnecessary round trips to the CDN edge. For files without content hashes in the name, particularly index.html, set a much shorter cache TTL of 300 seconds (five minutes) to one hour. This ensures that when you deploy an update, the new index.html propagates quickly and references the new hashed filenames.
Most modern build tools support content hashing out of the box. Webpack, Vite, esbuild, and Rollup all have configuration options for output filename patterns that include content hashes. Unity WebGL builds include version-specific filenames by default. If your build tool does not support hashing, you can achieve a similar effect by placing all assets in a version-numbered directory (like /v42/) and updating the directory name with each release.
Enable Compression
Compression reduces the transfer size of text-based files by 60 to 80 percent, which directly translates to faster load times. The two compression algorithms used by CDNs are gzip and Brotli. Brotli achieves roughly 15 to 20 percent better compression ratios than gzip on JavaScript and WebAssembly files, so prefer Brotli where available while keeping gzip as a fallback for older clients.
Most CDNs compress on the fly, but for large files like WebAssembly modules, pre-compressing during the build step gives better results because the compressor can spend more time optimizing the output. Upload pre-compressed versions alongside the originals (for example, game.wasm and game.wasm.br) and configure your CDN to serve the pre-compressed version when the browser sends an Accept-Encoding: br header. CloudFront and Cloudflare both support this pattern.
Verify that compression is working by opening your game in Chrome DevTools, navigating to the Network tab, and checking the Content-Encoding header on your JavaScript and WASM files. If it shows br or gzip, compression is active. If the header is missing, check your CDN configuration and make sure the file types are included in the compression policy. Common MIME types that should be compressed include application/javascript, application/wasm, text/html, text/css, and application/json.
Configure CORS and Security Headers
If your game is served from a different domain or subdomain than its assets (for example, the HTML page is on yourgame.com but assets load from cdn.yourgame.com), you need Cross-Origin Resource Sharing (CORS) headers on the asset responses. Without them, the browser blocks JavaScript from accessing textures loaded via fetch or XMLHttpRequest, WebGL textures loaded with crossOrigin set, and Web Audio buffers loaded from cross-origin URLs.
The simplest CORS configuration sets Access-Control-Allow-Origin: * on all asset responses, which allows any page to load your game assets. This is safe for public game assets since there is no sensitive data in texture files or JavaScript bundles. If you need to restrict which domains can embed your game, replace the wildcard with specific allowed origins.
For games that will be embedded in iframes on other sites, add the Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy headers if your game uses SharedArrayBuffer (required by some engine exports, including certain Unity WebGL configurations). Set Cross-Origin-Opener-Policy: same-origin and Cross-Origin-Embedder-Policy: require-corp on the game's HTML page, and ensure all cross-origin resources either include CORS headers or use the crossorigin attribute when loaded.
Implement Progressive Loading
Rather than making players wait for the entire game to download before showing anything, implement progressive loading to get content on screen as fast as possible. Load the minimum assets needed for the title screen (UI elements, a background image, the menu music if any) in the initial bundle, and then stream the remaining assets in the background while the player reads the title screen or navigates menus.
For level-based games, load only the current level's assets when the player starts that level, and preload the next level's assets while they play. This approach can reduce the initial load from 30 MB down to 3 to 5 MB, making the game feel nearly instant to start even though the full asset set is much larger. Display a progress indicator in the background showing how much of the next level is preloaded, so players know the game is working even if they advance quickly.
WebAssembly modules benefit from streaming compilation, where the browser compiles the Wasm code as it downloads rather than waiting for the complete file. To enable this, serve Wasm files with the correct Content-Type: application/wasm header and use WebAssembly.instantiateStreaming() instead of downloading the whole file and then compiling it. This can reduce the time from download start to game-ready by 30 to 50 percent for large Wasm modules.
Monitor and Invalidate
After deploying your CDN configuration, monitor the cache hit ratio through your CDN provider's dashboard. A well-configured CDN for a web game should achieve a cache hit ratio above 90 percent, meaning nine out of ten requests are served from the edge without contacting your origin. If the ratio is lower, check for files with short or missing cache headers, query parameters that vary between requests, or cookies being forwarded to the origin unnecessarily.
When you deploy an update, only invalidate the files that actually changed. Most CDN providers charge for invalidation requests (AWS gives 1,000 free per month, then charges per request), so invalidating only /index.html after a deployment is preferable to invalidating everything with a wildcard /*. Since your hashed asset files have new filenames with each build, they do not need invalidation, because the browser requests the new filename which has no cached copy at the edge.
Check edge latency by testing your game from different geographic locations using tools like WebPageTest, Pingdom, or GTmetrix. These tools let you run load tests from servers in different countries, showing you the actual download times players experience in each region. If certain regions show poor performance, verify that your CDN has edge nodes in those areas and consider adjusting your price class or switching to a provider with better coverage in those markets.
A properly configured CDN with content-hashed filenames, aggressive caching, and Brotli compression is the single most impactful performance optimization for self-hosted web games, often reducing load times by more than half while simultaneously cutting hosting costs and improving reliability.