CircleCI vs Travis

CircleCI excels with its setup process. All that's needed is a GitHub login and CircleCI automatically detects the settings for Ruby, Python, Node.js, Java and Clojure. The setup process is their most widely praised feature.

CircleCI can be connected to any project that is hosted on GitHub by logging in using the GitHub OAuth and adding the desired repository.

Whenever a new commit is pushed to GitHub, CircleCI runs the tests that have been already defined and if none of them fails, the build is deployed to the runtime environment.

Users can access the Virtual Machine via SSH and run commands.

In most cases CircleCI automatically get settings from your code. When it fails, edit circle.yml.

Tests can be parallelized across multiple machines reducing test times drastically. They support up to 8-way parallelization. Additionally, CircleCI caches the build environment.

Circle CI's web UI is clean and easy to use.

It gives all the information for a single build in a feed and gives the explanation for each step of the build, what it's doing and what the step is related to. On the top it displays author information and the time and date when the build was started and finished.

This is all done by giving only the most essential information without clogging the screen.

Support for Ruby, Python, Node, Java, PHP, RoR, DJ, JavaScript. It also detects settings for Ruby, Python, Node.js, Java and Clojure.

It als has support for: MySQL, MongoDB, PostgreSQL, Cassandra, Riak, Redis, SQLite, Solr, CouchDB, ElasticSearch, Neo4j, Couchbase, Lucene, Sphinx, ThriftDB, Memcache.

Alongside latest Chrome, Firefox and Webkit (installed using xvfb), CircleCi supports the use of Selenium, PhantomJS as well as tools like Capybara and Cucumber.

Support for RabbitMQ, Beanstalk and Resque through Redis.

CircleCI can continuously deliver Docker images to hosts that support Docker containers.

Eg:
./1.setup.sh 48s
./2.build.sh 56s
With this information, it's easy to find out which line of the script is the bottleneck of the build process.

Can specify the cache dependencies on

1. checksum "package.json"
2. Branch
3. BuildNum
4. Revision
5. Environment.variableName

For more details https://circleci.com/docs/2.0/caching/

CircleCI can notify via email, Hipchat, Campfire and more. And it does so only when necessary.

You can push multiple batches of code concurrently.

Support for Heroku, AWS, Engine Yard, dotCloud, Fabric, Nodejitsu, AppFog, Capistrano, Rockspace, Joynet.

Integration with Heroku is solid with the ability to automatically deploy or merge branches.

CircleCI is also very flexible with the deployment arrangement allowing SSH key management, deployment freedom including directly to a PaaS, using Capistrano, Fabric, arbitrary bash commands, or by auto-merging to another branch, or packaging code up to S3.

Travis is free for all public repositories on Github.

All that is needed to set up Travis is a configuration file (travis.yml) in the root of the repository where it will be installed and Travis takes care of the rest.

Travis registers every push to GitHub and automatically builds the branch by default.

Supports the most widely used technological stacks (Node, Ruby, PHP, Python etc...) for free.

Travis' VM are built on Ubuntu 12.04 64 bit Server Edition, with the exception of Objective-C builds, which are based on Mac OS X Mavericks.

Travis supports testing for different versions of the same runtime. All it takes is some lines in the travis.yml file.

Support for C, C++, Clojure, Erlang, Go, Groovy, Haskell, Java, JavaScript, Perl, PHP, Python, Ruby and Scala.

Travis CI has a large and helpful community which is quite accepting to new users and provides a great number of tutorials.

Starting at $129 you can use TravisPro, that adds the option of closed-source, private, repositories and personal support.