# Redirects, custom 404s, and SPA support

This feature is new, and requires Kubo 0.16 or later.

This feature enables support for redirects, single-page applications, custom 404 pages, and moving to IPFS-backed hosting without breaking existing links (opens new window).

# Evaluation

This feature is limited to websites hosted in web contexts with unique Origins (opens new window) for content roots, e.g., subdomain or DNSLink gateways.

Redirect logic will only be evaluated if the requested path is not in the DAG. Any performance impact associated with checking for the existence of a _redirects file or evaluating redirect rules will only be incurred for non-existent paths. If there are any errors reading or parsing the _redirects file, the error codes will be returned with an HTTP 500 status code.

# How to set up

To define rules that will be executed when the requested path is not found in the DAG, there must be a file named _redirects stored underneath the root CID of the website. This _redirects file must be a text file containing one or more lines that follow the format explained below.

# Format of the _redirects file

Each line contained within the _redirects file has 3 basic components:

from  to  [status]
  1. The from path. This specifies the path to be redirected from.
  2. The to path. This specifies the path to be redirected to.
  3. The status component. This part is optional and specifies the HTTP status code that will be returned. (301, 404, etc.)

For example, if you removed home.html and want to temporarily redirect traffic from home.html to index.html, the _redirects file should contain a line that looks something like this:

/home.html /index.html 302

# Status codes

  • 200 - OK (redirect will be treated as a rewrite, returning payload from alternative content path without changing the URL shown in the browser).
  • 301 - Permanent redirect (the default status).
  • 302 - Found (commonly used for temporary redirects).
  • 404 - Not found (defines custom 404 page).
  • 410 - Gone (the requested content has been permanently removed).
  • 451 - Unavailable for legal reasons.

# Placeholders

Placeholders are named variables that can be used to match path segments in the from path and inject them into the to path.

This is useful for redirecting users to their desired content, even if the way your website is organized changed.

For example, if I wanted to search for an article titled "hello world" that was written on June 15, 2022, I could search for it like this: /posts/06/15/2022/hello-world and be redirected to /articles/2022/06/15/hello-world

/posts/:month/:day/:year/:title  /articles/:year/:month/:day/:title  301

There is also a special catch-all placeholder named :splat which represents everything captured via *.

/blog/*  /new-blog/:splat  302

# Compatibility

IPFS hosting supports only a subset of pre-existing standards supported by Cloudflare (opens new window) and Netlify (opens new window).
There is no overwrite/shadowing: the file is evaluated only when requested path is not found in a DAG.

TIP

For more detailed information about supported features, check out the _redirects file specification (opens new window).

# Examples

# Catch all and PWA/SPA support

The 200 status will be treated as a rewrite, returning OK without changing the URL shown in the browser. This staus code can be used to build Progressive Web Apps (opens new window) and Single Page Applications (opens new window).

/app/* /app/index.html 200

Opening /app/this-does-not-exist will return HTTP 200 response with content from /app/index.html

# Redirect an old URL to a new place

The 301 status is a permanent redirect, this is the default status code used when no code is specified.
The two rules below mean the same thing:

/old/docs.html /new/documentation.html
/old/docs.html /new/documentation.html 301

The 302 status is commonly used for temporary redirects.

/home /under-construction.html 302

For advanced and catch-all redirects, see Placeholders.

# Add a custom 404 page to your website

Since the _redirects is evaluated only when requested path does not exist,
it is possible to define a custom 404 page for your website:

/* /custom-404.html 404

With the above rule, opening /this-does-not-exist will return HTTP 404 Not Found error response with the payload of a custom error page defined in custom-404.html.