Free Online Nginx Configuration Validator
Check Nginx configuration syntax and common issues.
About the Nginx Configuration Validator
Nginx configuration is a tree of contexts and directives. A missing semicolon, an unbalanced brace, or a misspelled directive can prevent the service from reloading, while a logically valid file can still expose the wrong site or accept uploads larger than the application expects. This validator performs a syntax-level review in the browser. It is designed to catch the mistakes that are easy to introduce by hand and hard to spot in a long configuration file.
The scanner walks the text character by character, tracking single quotes, double quotes, comments, braces, and
semicolons. That makes it more reliable than a line-by-line check, because quoted strings may contain braces or
semicolons that must be ignored. When a closing brace appears with unprocessed text before it, the tool reports a
missing semicolon and gives the line number. It also reports negative nesting, unclosed braces at end of file,
and unterminated quotes. These are the failures that nginx -t usually reports first.
After the structural pass, the tool locates server blocks and inspects their directives. It checks
for a listen directive, a server_name, and either a document root, an alias, or a
proxy_pass. It reports duplicate server names, a wildcard catch-all name, a TLS certificate without
an SSL listener, a listener on port 443 without the SSL flag, and a proxy pass without a forwarded Host header.
The client_max_body_size directive is checked because its default of one megabyte often breaks file
uploads in ways that only appear in production.
The results are advisory. A valid configuration may deliberately omit a server name, rely on a global
client_max_body_size, or use an include file that this tool cannot see. Nginx also has many modules
whose directives are unknown here. Always run nginx -t on the target server before reloading, and
keep a tested backup of the previous configuration. The validator never connects to a server and never sends your
configuration anywhere; everything is parsed locally.
How to use this tool
- Paste a full
nginx.confor a single site configuration. - Click Check configuration.
- Fix structural errors first, then review the server-level warnings.
- Copy or download the report and compare it with
nginx -toutput.
Frequently asked questions
Is this a replacement for nginx -t?
No. nginx -t is authoritative. This tool performs static checks and cannot load modules, resolve includes, or validate every directive.
Why does an include file cause warnings?
Directives inside an included file are not visible in the pasted text. The validator only sees what you paste, so some global settings may appear missing.
Does it check SSL certificate files?
No. It only checks whether certificate directives and SSL listeners are consistent in the text. File existence and certificate validity must be verified on the server.