Nginx Cheatsheet

Gzip and Performance

Use this Nginx reference while you build software engineering projects, review code for technical interview prep, or polish examples for a software engineer resume.

Gzip Compression

http {
    gzip              on;
    gzip_vary         on;             # Add Vary: Accept-Encoding header
    gzip_proxied      any;           # Compress responses for proxied requests
    gzip_comp_level   6;             # 1 (fastest) – 9 (best compression); 5-6 is the sweet spot
    gzip_min_length   256;           # Don't compress tiny responses
    gzip_types
        text/plain
        text/css
        text/javascript
        application/javascript
        application/json
        application/xml
        application/rss+xml
        image/svg+xml
        font/woff2;
    # Never add image/jpeg, image/png — already compressed
}

Gzip Directive Reference

Directive	Recommended	What it does
`gzip`	`on`	Enable gzip
`gzip_vary`	`on`	Add `Vary: Accept-Encoding` (required for CDNs/caches)
`gzip_comp_level`	`6`	Compression level 1–9
`gzip_min_length`	`256`	Skip tiny files (bytes)
`gzip_types`	see above	MIME types to compress (`text/html` always included)
`gzip_proxied`	`any`	Compress responses for proxied clients
`gzip_buffers`	`16 8k`	Buffers used for compression
`gzip_http_version`	`1.1`	Min HTTP version to compress
`gzip_disable`	`"msie6"`	Skip gzip for matching `User-Agent`

Pre-compressed Files (gzip_static)

Serve .gz files that already exist on disk — no CPU overhead per request:

location /assets/ {
    root /var/www/app;
    gzip_static on;    # Serves file.js.gz when file.js is requested
}

Build step: gzip -k -9 dist/assets/*.js dist/assets/*.css

Brotli (requires module)

Nginx has no built-in brotli. Debian/Ubuntu package the ngx_brotli module for their distro nginx; the official nginx.org OSS packages do not include it (compile ngx_brotli yourself or use NGINX Plus).

# Debian/Ubuntu distro nginx (auto-loads via /etc/nginx/modules-enabled/)
sudo apt install libnginx-mod-http-brotli-filter libnginx-mod-http-brotli-static

# Self-compiled ngx_brotli (nginx.org builds): load the dynamic modules
load_module modules/ngx_http_brotli_filter_module.so;
load_module modules/ngx_http_brotli_static_module.so;

brotli              on;
brotli_comp_level   6;           # 0–11
brotli_static       on;          # Serve .br pre-compressed files
brotli_types
    text/plain text/css
    application/javascript application/json
    image/svg+xml font/woff2;

Sendfile and TCP Tuning

http {
    sendfile        on;       # Zero-copy for static files
    tcp_nopush      on;       # Bundle headers + first data in one TCP packet
    tcp_nodelay     on;       # Disable Nagle — reduce latency on keepalives
}

Keepalive Connections

http {
    keepalive_timeout  65;      # How long to keep idle client connection open (s)
    keepalive_requests 1000;    # Max requests per keepalive connection
}

Worker Tuning

# /etc/nginx/nginx.conf
worker_processes      auto;         # One per logical CPU
worker_rlimit_nofile  65535;        # Raise OS file descriptor limit

events {
    worker_connections  4096;       # Simultaneous connections per worker
    multi_accept        on;         # Accept all queued connections at once
    use                 epoll;      # Best I/O event model on Linux
}

Max connections = worker_processes × worker_connections.

Open File Cache

http {
    open_file_cache          max=10000 inactive=20s;
    open_file_cache_valid    30s;
    open_file_cache_min_uses 2;
    open_file_cache_errors   on;
}

Caches file descriptors, sizes, and mtimes — reduces stat() syscalls on high-traffic static sites.

Client Buffers

http {
    client_body_buffer_size    128k;
    client_header_buffer_size    1k;
    client_max_body_size          50m;   # Max upload size
    large_client_header_buffers  4 8k;
}

Upstream Keepalives

upstream backend {
    server 127.0.0.1:3000;
    keepalive 32;    # Idle keepalive connections to upstream
}

location / {
    proxy_pass http://backend;
    proxy_http_version 1.1;
    proxy_set_header Connection "";  # Required for upstream keepalives
}

Rate Limiting

http {
    limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;

    server {
        location /api/ {
            limit_req zone=api burst=20 nodelay;
            proxy_pass http://backend;
        }
    }
}

Parameter	Example	Meaning
`rate`	`10r/s`	Sustained request rate
`burst`	`20`	Allow up to 20 extra requests to queue
`nodelay`	—	Process burst immediately, not delayed
`delay=N`	`delay=5`	Delay requests after N, drop excess

Connection Limiting

http {
    limit_conn_zone $binary_remote_addr zone=conn_limit:10m;

    server {
        location / {
            limit_conn conn_limit 20;   # Max 20 concurrent connections per IP
        }
    }
}