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Validating URI References per RFC 3986

Project description

A Python implementation of RFC 3986 including validation and authority parsing.


Use pip to install rfc3986 like so:

pip install rfc3986


Apache License Version 2.0

Example Usage

The following are the two most common use cases envisioned for rfc3986.

Replacing urlparse

To parse a URI and receive something very similar to the standard library’s urllib.parse.urlparse

from rfc3986 import urlparse

ssh = urlparse('ssh://')
print(ssh.scheme)  # => ssh
print(ssh.userinfo)  # => user
print(ssh.params)  # => None
print(ssh.port)  # => 29418

To create a copy of it with new pieces you can use copy_with:

new_ssh = ssh.copy_with(
print(new_ssh.scheme)  # => https
print(new_ssh.userinfo)  # => None
# etc.

Strictly Parsing a URI and Applying Validation

To parse a URI into a convenient named tuple, you can simply:

from rfc3986 import uri_reference

example = uri_reference('')
email = uri_reference('')
ssh = uri_reference('ssh://')

With a parsed URI you can access data about the components:

print(example.scheme)  # => http
print(email.path)  # =>
print(ssh.userinfo)  # => user
print(  # =>
print(ssh.port)  # => 29418

It can also parse URIs with unicode present:

uni = uri_reference(b'\xe2\x98\x83')  # ☃
print(uni.query)  # utf8=%E2%98%83

With a parsed URI you can also validate it:

if ssh.is_valid():['git', 'clone', ssh.unsplit()])

You can also take a parsed URI and normalize it:

mangled = uri_reference('hTTp://exAMPLe.COM')
print(mangled.scheme)  # => hTTp
print(mangled.authority)  # => exAMPLe.COM

normal = mangled.normalize()
print(normal.scheme)  # => http
print(mangled.authority)  # =>

But these two URIs are (functionally) equivalent:

if normal == mangled:

Your paths, queries, and fragments are safe with us though:

mangled = uri_reference('hTTp://exAMPLe.COM/Some/reallY/biZZare/pAth')
normal = mangled.normalize()
assert normal == 'hTTp://exAMPLe.COM/Some/reallY/biZZare/pAth'
assert normal == ''
assert normal != ''

If you do not actually need a real reference object and just want to normalize your URI:

from rfc3986 import normalize_uri

assert (normalize_uri('hTTp://exAMPLe.COM/Some/reallY/biZZare/pAth') ==

You can also very simply validate a URI:

from rfc3986 import is_valid_uri

assert is_valid_uri('hTTp://exAMPLe.COM/Some/reallY/biZZare/pAth')

Requiring Components

You can validate that a particular string is a valid URI and require independent components:

from rfc3986 import is_valid_uri

assert is_valid_uri('http://localhost:8774/v2/resource',

# Assert that a mailto URI is invalid if you require an authority
# component
assert is_valid_uri('', require_authority=True) is False

If you have an instance of a URIReference, you can pass the same arguments to URIReference#is_valid, e.g.,

from rfc3986 import uri_reference

http = uri_reference('http://localhost:8774/v2/resource')
assert uri.is_valid(require_scheme=True,

# Assert that a mailto URI is invalid if you require an authority
# component
mailto = uri_reference('')
assert uri.is_valid(require_authority=True) is False


  • rfc3987

    This is a direct competitor to this library, with extra features, licensed under the GPL.

  • uritools

    This can parse URIs in the manner of RFC 3986 but provides no validation and only recently added Python 3 support.

  • Standard library’s urlparse/urllib.parse

    The functions in these libraries can only split a URI (valid or not) and provide no validation.


This project follows and enforces the Python Software Foundation’s Code of Conduct.

If you would like to contribute but do not have a bug or feature in mind, feel free to email Ian and find out how you can help.

The git repository for this project is maintained at

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