Translating .htaccess to nginx covers only a narrow, explicitly documented subset of Apache directives, and every conditional or unsupported rule is reported with its original line number instead of being silently rewritten. The htaccess to Nginx Converter is built around that narrow contract: it accepts a focused document-root excerpt, converts the rules it knows how to handle, and surfaces warnings for anything that requires human judgment. Apache's mod_rewrite and Nginx's ngx_http_rewrite_module share vocabulary but not semantics, so a converter that emits plausible-looking but non-equivalent configuration can break routing, create redirect loops, or expose a route that was previously protected. For that reason the tool stays small on purpose. It handles permanent and temporary redirects, the L flag, document-root pattern adjustments, directory-listing disablement, local 404 handling and X-Robots-Tag headers, and reports everything else. Treating the output as a reviewed fragment — never as a drop-in nginx.conf — is what makes the migration safe. Where a source .htaccess contains authentication, proxy logic, or CMS front-controller rules, the converter leaves them for manual work, because their migration is engineering work rather than bulk text replacement.
Why a Direct htaccess to nginx Conversion Cannot Be Universal
Apache discovers .htaccess files while walking the directory tree during request processing. Each request can trigger a fresh parse if AllowOverride permits it, which is why per-directory overrides, mod_rewrite, and authentication checks are commonly expressed in .htaccess. Nginx does none of that. The server reads centralized configuration at startup, evaluates server and location contexts before a request reaches the rewrite phase, and treats per-directory config as a design choice Nginx chose to omit for performance. The two servers match identical-looking regular expressions against different strings, with different escaping rules, different query handling, and different loop behavior.
The practical consequence is that any tool claiming to translate .htaccess into nginx has to draw a line. A converter that silently rewrites a RewriteCond into an unconditional block, or guesses that an unfamiliar flag means something plausible, can take down a public site. The htaccess to Nginx Converter draws that line publicly: a fixed directive subset is supported, and anything outside it is reported with the original line number so the operator can resolve it against the official Apache and Nginx documentation.
Directives the Converter Translates
The conversion contract covers three rewrite flag combinations, one directory-listing control, one local error page, and one response header. Anything outside this set is not converted automatically.
| Apache .htaccess directive | Nginx equivalent emitted | Notes |
|---|---|---|
| RewriteRule pattern target [R=301] | rewrite ^pattern /target permanent; | Permanent redirect; cacheable by browsers and intermediaries. |
| RewriteRule pattern target [R=302] or [R] | rewrite ^pattern /target redirect; | Temporary redirect; safer for staged rollouts. |
| RewriteRule pattern target [L] | rewrite ^pattern /target last; | Internal rewrite ending further rule processing. |
| Options -Indexes | autoindex off; | Disables directory listing in the converted context. |
| ErrorDocument 404 /path | error_page 404 /path; | Local path only; external URLs are not supported by the converter. See the Nginx error_page directive for placement rules. |
| Header set X-Robots-Tag "value" | add_header X-Robots-Tag "value"; | Quoted value required; conditional headers are not converted. |
RewriteRule flags outside the automatic set — QSA, END, F, G, B, NC, and similar — stop conversion for that rule and surface a warning. A bracketed flag list that contains only supported entries proceeds normally.
What the Converter Refuses to Guess
Three categories of input always produce warnings rather than guessed output, because guessing them would silently change traffic behavior.
- RewriteCond lines. Apache conditions can inspect HTTPS state, host names, files, directories, query strings, headers, and captured groups, and their evaluation order interacts with the rewrite engine. When a RewriteRule follows a condition, the tool suppresses the rule too, rather than emitting an unconditional redirect that could change traffic, create a loop, or expose a route.
- Unknown RewriteRule flags. Flags outside the supported set change access, processing, or response body. Their semantics cannot be erased by translating them away, so the converter reports the original line and stops.
- The dash target. An Apache rule whose substitution is a single - often combines with flags that alter access or processing without changing the URI. A literal dash is not a safe Nginx replacement, so the rule is withheld and a warning is emitted.
Other inputs the converter does not handle: authentication and authorization directives, hotlink protection, proxy configuration, CMS front-controller rules, environment variable manipulation, and directive containers. Treat any migration that contains these as engineering work, not bulk text replacement.
How to Use the htaccess to Nginx Converter
- Open the htaccess to Nginx Converter and paste a focused excerpt from a single document-root .htaccess file. Keep the paste short enough to review by eye; if it does not fit on a screen, split it into smaller excerpts.
- Read the converted output and the line-numbered warnings together. Each warning refers to the original line number in the Apache excerpt so you can locate the rule without searching.
- Resolve every warning manually against the Apache mod_rewrite introduction and the relevant Nginx documentation. Decide whether the rule needs a rewrite, a map, an if block in a controlled context, or a complete redesign.
- Assemble the approved lines into a version-controlled Nginx configuration file. Place rewrite and error_page lines inside the correct server or location block for your site, not at the top of the file.
- Back up the active configuration, run nginx -t on the assembled file, and stage representative requests before any reload. A guide such as How to Get an Nginx Config That Actually Works walks through the surrounding context choices for static sites if you are starting from a blank slate.
Where the Output Belongs in Nginx
The fragment the converter emits does not define a listen port, a server_name, TLS, a document root, an upstream, a PHP handler, or a log directive. Those are decisions that depend on the actual application and the surrounding architecture, and the tool deliberately does not make them. Each emitted line must be placed where the Nginx directive reference says it belongs.
Rewrite and error_page lines typically go inside the server block, and a more specific rule can be scoped to a location block that matches the relevant URI prefix. autoindex off and add_header can be placed at http, server, or location level depending on how broadly the rule should apply. If the Apache source used RewriteRule patterns that began without a leading slash — common in document-root .htaccess — the converter inserts that leading slash on the way out, because Nginx rewrite patterns see a URI that begins with /. This is a documented scope assumption for document-root files and is not a universal transformation for nested .htaccess or Alias mappings.
Validating and Reloading Without Downtime
Even a syntactically valid Nginx line can be wrong for its context, which is why validation matters more than the conversion itself. The minimum safe sequence is:
- Keep the current production configuration as a recoverable backup, and keep an open recovery session in case the new file fails to load.
- Run nginx -t against the assembled configuration. The tool reports syntax errors but cannot detect lines that are syntactically valid and semantically wrong for their context.
- Test representative requests on staging or behind a maintenance flag. Cover old paths, new paths, query strings, alternate hosts, and HTTPS behavior.
- Confirm the response Location header rather than trusting the browser address bar alone, especially when redirects are involved.
Permanent redirects deserve extra care because browsers and intermediaries may cache them, so a wrong permanent rule can take days to undo. Where practical, start with redirect (temporary) in a controlled environment, switch to permanent only after the redirect matrix has been verified, and keep the temporary variant ready to revert to. A failed reload or redirect loop can remove a public site from the air quickly, and a cached permanent redirect can keep it offline for as long as clients hold onto it.
The htaccess to Nginx Converter is built for the first pass of that workflow: a focused excerpt, a small set of supported rules, line-numbered warnings for everything else, and an output that is honest about being a fragment. Anything more ambitious — authentication, proxying, CMS front-controller rewrites, conditional logic — belongs in a manual migration against the Apache and Nginx documentation, not in a bulk conversion.