sphinx.ext.intersphinx – Link to other projects’ documentation

Added in version 0.5.

This extension can generate links to the documentation of objects in external projects, either explicitly through the external role, or as a fallback resolution for any other cross-reference.

Usage for fallback resolution is simple: whenever Sphinx encounters a cross-reference that has no matching target in the current documentation set, it looks for targets in the external documentation sets configured in intersphinx_mapping. A reference like :py:class:`zipfile.ZipFile` can then link to the Python documentation for the ZipFile class, without you having to specify where it is located exactly.

When using the external role, you can force lookup to any external projects, and optionally to a specific external project. A link like :external:ref:`comparison manual <comparisons>` will then link to the label “comparisons” in whichever configured external project, if it exists, and a link like :external+python:ref:`comparison manual <comparisons>` will link to the label “comparisons” only in the doc set “python”, if it exists.

Behind the scenes, this works as follows:

  • Each Sphinx HTML build creates a file named objects.inv that contains a mapping from object names to URIs relative to the HTML set’s root.

  • Projects using the Intersphinx extension can specify the location of such mapping files in the intersphinx_mapping config value. The mapping will then be used to resolve both external references, and also otherwise missing references to objects into links to the other documentation.

  • By default, the mapping file is assumed to be at the same location as the rest of the documentation; however, the location of the mapping file can also be specified individually, e.g. if the docs should be buildable without Internet access.


To use Intersphinx linking, add 'sphinx.ext.intersphinx' to your extensions config value, and use these config values to activate linking:


This config value contains the locations and names of other projects that should be linked to in this documentation.

Relative local paths for target locations are taken as relative to the base of the built documentation, while relative local paths for inventory locations are taken as relative to the source directory.

When fetching remote inventory files, proxy settings will be read from the $HTTP_PROXY environment variable.


Added in version 1.0.

A dictionary mapping unique identifiers to a tuple (target, inventory). Each target is the base URI of a foreign Sphinx documentation set and can be a local path or an HTTP URI. The inventory indicates where the inventory file can be found: it can be None (an objects.inv file at the same location as the base URI) or another local file path or a full HTTP URI to an inventory file.

The unique identifier can be used in the external role, so that it is clear which intersphinx set the target belongs to. A link like external:python+ref:`comparison manual <comparisons>` will link to the label “comparisons” in the doc set “python”, if it exists.


To add links to modules and objects in the Python standard library documentation, use:

intersphinx_mapping = {'python': ('https://docs.python.org/3', None)}

This will download the corresponding objects.inv file from the Internet and generate links to the pages under the given URI. The downloaded inventory is cached in the Sphinx environment, so it must be re-downloaded whenever you do a full rebuild.

A second example, showing the meaning of a non-None value of the second tuple item:

intersphinx_mapping = {'python': ('https://docs.python.org/3',

This will read the inventory from python-inv.txt in the source directory, but still generate links to the pages under https://docs.python.org/3. It is up to you to update the inventory file as new objects are added to the Python documentation.

Multiple targets for the inventory

Added in version 1.3.

Alternative files can be specified for each inventory. One can give a tuple for the second inventory tuple item as shown in the following example. This will read the inventory iterating through the (second) tuple items until the first successful fetch. The primary use case for this to specify mirror sites for server downtime of the primary inventory:

intersphinx_mapping = {'python': ('https://docs.python.org/3',
                                  (None, 'python-inv.txt'))}

For a set of books edited and tested locally and then published together, it could be helpful to try a local inventory file first, to check references before publication:

intersphinx_mapping = {
            ('../../otherbook/build/html/objects.inv', None)),

Old format for this config value

Deprecated since version 6.2.


This is the format used before Sphinx 1.0. It is deprecated and will be removed in Sphinx 8.0.

A dictionary mapping URIs to either None or an URI. The keys are the base URI of the foreign Sphinx documentation sets and can be local paths or HTTP URIs. The values indicate where the inventory file can be found: they can be None (at the same location as the base URI) or another local or HTTP URI.


intersphinx_mapping = {'https://docs.python.org/': None}

The maximum number of days to cache remote inventories. The default is 5, meaning five days. Set this to a negative value to cache inventories for unlimited time.


The number of seconds for timeout. The default is None, meaning do not timeout.


timeout is not a time limit on the entire response download; rather, an exception is raised if the server has not issued a response for timeout seconds.


Added in version 4.3.

Changed in version 5.0: Changed default value from an empty list to ['std:doc'].

A list of strings being either:

  • the name of a specific reference type in a domain, e.g., std:doc, py:func, or cpp:class,

  • the name of a domain, and a wildcard, e.g., std:*, py:*, or cpp:*, or

  • simply a wildcard *.

The default value is ['std:doc'].

When a non-external cross-reference is being resolved by intersphinx, skip resolution if it matches one of the specifications in this list.

For example, with intersphinx_disabled_reftypes = ['std:doc'] a cross-reference :doc:`installation` will not be attempted to be resolved by intersphinx, but :external+otherbook:doc:`installation` will be attempted to be resolved in the inventory named otherbook in intersphinx_mapping. At the same time, all cross-references generated in, e.g., Python, declarations will still be attempted to be resolved by intersphinx.

If * is in the list of domains, then no non-external references will be resolved by intersphinx.

Explicitly Reference External Objects

The Intersphinx extension provides the following role.


Added in version 4.4.

Use Intersphinx to perform lookup only in external projects, and not the current project. Intersphinx still needs to know the type of object you would like to find, so the general form of this role is to write the cross-refererence as if the object is in the current project, but then prefix it with :external. The two forms are then

  • :external:domain:reftype:`target`, e.g., :external:py:class:`zipfile.ZipFile`, or

  • :external:reftype:`target`, e.g., :external:doc:`installation`. With this shorthand, the domain is assumed to be std.

If you would like to constrain the lookup to a specific external project, then the key of the project, as specified in intersphinx_mapping, is added as well to get the two forms

  • :external+invname:domain:reftype:`target`, e.g., :external+python:py:class:`zipfile.ZipFile`, or

  • :external+invname:reftype:`target`, e.g., :external+python:doc:`installation`.

Using Intersphinx with inventory file under Basic Authorization

Intersphinx supports Basic Authorization like this:

intersphinx_mapping = {'python': ('https://user:password@docs.python.org/3',

The user and password will be stripped from the URL when generating the links.