When you search for some Maven artifact (Java library), you use one of two methods:
Google / DuckDuckGo / ... - that's fine, and it will mostly point you to mvnrepository.com, but this often doesn't return best results, especially when the library gets retired and moves to new groupId:artifactId or when you search for Maven plugin / archetype / java class. Also it doesn't say anything about library's popularity.
Specialized search engine like mvnrepository.com, search.maven.org, javalibs.com etc.
A short time back I also asked Java community on Google+ which search engine they use. These were the answers (181 people voted). Later on you will see that mvnrepository.com currently prevails because it's easily searchable by Google, exists for 10 long years and does a pretty good job (at least for basic dependency search in Central Repository):
Search engines search capabilities:
There are total 8 tests which tested the search engine to it's limits. Note that on search.maven.org I didn't use "Advanced search", because it requires precise knowledge what you're looking for, it's extra hassle and most people don't know about that feature anyways. If the result I was looking for was within several first results (first 5 results if not specified otherwise), the search engine would receive one point, otherwise zero. These are summary results:
+ pretty good search engine
+ autocomplete
+ retired artifacts are marked
+ dependencies, plugins, archetypes, java classes, javadoc, dependency trees
+ libraries from several repositories, not just Maven Central
- updated two times a week
test results:8 / 8 tests passed
libraries.io (a.k.a. search everything, find nothing, since 2015)
+ much more than just Java libraries - javascript, ruby etc.
+ very nice integration with GitHub
- from Java libraries just Maven Central
- terrible search engine (see lower for comprehensive search tests)
- it seems there's no regular update mechanism for the time being, often it doesn't contain current information
test results:1 / 8 tests passed
bintray.com (a.k.a. Maven Central alternative, since 2012)
+ has more than just Java libraries from Central (jcenter)
- seldom updated
- terrible search engine (see lower for comprehensive search tests)
search term: org.hibernate:hibernate-search-engine
Explanation: searching for groupId:artifactId, what could go wrong?
Results:
mvnrepository.com:
1
search.maven.org:
0 (wheel keeps turning, but no result)
javalibs.com:
1
libraries.io:
0
bintray.com:
0
maven-repository.com:
0
search term: org.hibernate hibernate-search-engine
Explanation: searching for "groupId artifactId", what could go wrong?
Results:
mvnrepository.com:
1
search.maven.org:
1
javalibs.com:
1
libraries.io:
0
bintray.com:
0 (found 5.4.0.Alpha1 which is over 1 year old???)
maven-repository.com:
1
search term: spring
Explanation: This is very hard test, because I'm not specifying exactly what I'm looking for, just a name of the framework.
Results:
mvnrepository.com:
1
search.maven.org:
0
javalibs.com:
1
libraries.io:
0
bintray.com:
0
maven-repository.com:
0
search term: hibernate search
Explanation: This is moderately hard test, because even though there are just few "Hibernate Search" libraries, there are lots of "Hibernate" libraries and "search" is a common word. Moreover there's a deprecated Hibernate Search artifact and the search engine should warn you about it somehow.
Results:
mvnrepository.com:
1
search.maven.org:
0 (found deprecated version without any warning)
javalibs.com:
1
libraries.io:
1
bintray.com:
0
maven-repository.com:
0
search term: spring-webmvc
Explanation: This is fairly easy test, spring-webmvc is an artifactId. This should be within first 3 results.
Results:
mvnrepository.com:
1
search.maven.org:
1
javalibs.com:
1
libraries.io:
0 (found 4.2.7.RELEASE)
bintray.com:
0
maven-repository.com:
1
search term: hsql
Explanation: This is very hard test, hsql is just part of the name (full name is hsqldb).
Results:
mvnrepository.com:
0
search.maven.org:
0
javalibs.com:
1
libraries.io:
0
bintray.com:
0
maven-repository.com:
0
search term: <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> </dependency>
Explanation: You wouldn't belive how many people search this way.
Results:
mvnrepository.com:
1
search.maven.org:
0
javalibs.com:
1
libraries.io:
0
bintray.com:
0
maven-repository.com:
0
search term: junit-4.12.jar
Explanation: Again you wouldn't belive ...
Results: