#robots #parser #txt #google #txt-file #web-crawler #matcher

bin+lib robotstxt

A native Rust port of Google's robots.txt parser and matcher C++ library

2 unstable releases

0.3.0 Feb 13, 2021
0.2.0 May 24, 2020
0.1.0 Apr 19, 2019

#667 in Parser implementations

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508 downloads per month
Used in 4 crates


871 lines


Crates.io Docs.rs Apache 2.0

A native Rust port of Google's robots.txt parser and matcher C++ library.

  • Native Rust port, no third-part crate dependency
  • Zero unsafe code
  • Preserves all behavior of original library
  • Consistent API with the original library
  • 100% google original test passed


robotstxt = "0.3.0"

Quick start

use robotstxt::DefaultMatcher;

let mut matcher = DefaultMatcher::default();
let robots_body = "user-agent: FooBot\n\
                   disallow: /\n";
assert_eq!(false, matcher.one_agent_allowed_by_robots(robots_body, "FooBot", "https://foo.com/"));


Quoting the README from Google's robots.txt parser and matcher repo:

The Robots Exclusion Protocol (REP) is a standard that enables website owners to control which URLs may be accessed by automated clients (i.e. crawlers) through a simple text file with a specific syntax. It's one of the basic building blocks of the internet as we know it and what allows search engines to operate.

Because the REP was only a de-facto standard for the past 25 years, different implementers implement parsing of robots.txt slightly differently, leading to confusion. This project aims to fix that by releasing the parser that Google uses.

The library is slightly modified (i.e. some internal headers and equivalent symbols) production code used by Googlebot, Google's crawler, to determine which URLs it may access based on rules provided by webmasters in robots.txt files. The library is released open-source to help developers build tools that better reflect Google's robots.txt parsing and matching.

Crate robotstxt aims to be a faithful conversion, from C++ to Rust, of Google's robots.txt parser and matcher.


$ git clone https://github.com/Folyd/robotstxt
Cloning into 'robotstxt'...
$ cd robotstxt/tests 
$ mkdir c-build && cd c-build
$ cmake ..
$ make
$ make test
Running tests...
Test project ~/robotstxt/tests/c-build
    Start 1: robots-test
1/1 Test #1: robots-test ......................   Passed    0.33 sec


The robotstxt parser and matcher Rust library is licensed under the terms of the Apache license. See LICENSE for more information.

No runtime deps