Scrutinizer CI vs Circle CI comparison of Continuous Integration servers
What are the differences between Scrutinizer CI and Circle CI?

Scrutinizer CI

https://scrutinizer-ci.com

Circle CI

https://circleci.com
Unique feature

Ongoing statical analysis

Premium Support

Type of product

SaaS

SaaS, Self-hosted / On Premise

Offers a free plan

Yes

Free for open source projects

Yes

Provides a free plan for it's SaaS solution, for up to 1000 build minutes per month, 1 container and 1 concurrent job. On top of this, it has a special Free Tier for open source projects, which extend the number of containers and concurrent jobs available.
Predictable pricing

Yes

Three different paid monthly tiers

Yes

Provides a calculator, based on the number of concurrent jobs and containers, which can be used to determine pricing before purchase. They also give a guideline based on the number of developers you employ (2-3 containers per full-time developer)
Support / SLA

N/A

Not specifically mentioned, probably not.

Yes

While it's community is not quite as vibrant as it is for Jenkins, CircleCI even offers support premium support for companies who cannot afford any downtime in their CI/CD pipelines (https://circleci.com/support/premium-support/). For the regular plans, all plans except the free tier offer official email support. The free tier only includes community support (Discuss, StackOverflow, etc.)
Paralellism
Every CI servers tends to address this differently (parallel, distributed, build matrix). Some of it is just marketing, and some is just nuance. For this table, parallel means that tasks can be run concurrently on the same machine, distributed means that tasks can be scaled horizontally, on multiple machines
How to split tests in parallel in optimal way with Knapsack Pro

Yes

Automated parallalelization for code analysis, as well as support for running tasks in parallel

Yes

CircleCI can run builds in parallel, each build in a completely isolated environment by using containers.
Distributed builds
distributed means that tasks can be scaled horizontally, on multiple machines
How to split tests in parallel in optimal way with Knapsack Pro

N/A

Unclear from the documentation (probably not)

Yes

The SaaS version distributes builds by default, while the self-hosted version has all the tools built-in for managing the cluster of builder machines.
Containers support / Build environment

Yes

Tests run in isolated containers. Docker support available.

Yes

CircleCI runs every build in a container, or VM, ensuring an isolated, local scope for each build. The environment is also reset with each build, which can highlight hard-to-track issues related to assumptions about the environment that the project is deployed to.
Analytics / Status overview
Analytics and overview referrs to the ability to, at a glance, see what's breaking (be it a certain task, or the build for a specific project)

Yes

Besides classic CI overview, they also provide static code analysis insights, which is a differentiator for Scrutinizer

Yes

Available by default in Circle CI: https://circleci.com/docs/2.0/status/#section=jobs. Aditionally, the Insights Dashboard provides a very useful overview on build times, error rates and status for your projects: https://circleci.com/docs/2.0/insights/#section=jobs
Management support
How easy is it to manage users / projects / assign roles and permissions and so on

Yes

Additional seats available for every plan at $14.90 per seat, per month.

No (partial)

Using the Cloud plan for Circle CI requires no dedicated person for maintanence / management of the service. The CircleCI Server option (self-hosted) is also hassle free, as the process of installing and managing CircleCI and it's dependencies is automated. Developers are also given SSH acces to the builds (not the whole environment), while sys-admins can work on the host machine without worry about affecting the builds (which are containerized).
Self-hosted option

No

Yes

Hosted plans / SaaS

Yes

Yes

Build pipelines
A continuous delivery pipeline is a description of the process that the software goes through from a new code commit, through testing and other statical analysis steps all the way to the end-users of the product.

Yes

Pipelines as code (YML files)

Yes

Pipelines in CircleCI are defined declaratively using an Yaml config file. CircleCI has special provisions for storing secrets in these files.
Reports
Reports are about the abilty to see specific reports (like code coverage or custom ones), but not necesarily tied in into a larger dashboard.

Yes

Yes

Reports are available
Ecosystem
Besides the official documentation and software, is there a large community using this product? Are there any community-driven tools / plugins that you can use?

No

No plugin support in CircleCI, plugins for other tools

While CircleCI doesn't natively support plugins, it's core features address all of the core functionality that a CI/CD service needs. For integrating with other platforms or tools, there are integrations such as https://slack.com/apps/A0F7VRE7N-circleci. Certain jobs are available as CircleCI Orbs: https://circleci.com/orbs/
Specific language support: Ruby
Some CI servers have built-in support for parsing RSpec or Istanbul output for example and we mention those. Some others make it even easier by detecting Gemfiles or package.json and automate parts of the process for the developer.

Yes

Code analysis (automated code reviews) are available for Ruby, as well as specific documentation for setting up a Ruby project: https://scrutinizer-ci.com/docs/guides/ruby. Frameworks like Ruby on Rails are supported. They also provide tools like bundler-audit, for identifying vulnerable gems: https://scrutinizer-ci.com/docs/tools/ruby/bundler-audit/

Yes

For collecting test metadata and coverage, there is built-in support for Ruby (specifically, Cucumber and RSpec). Setting this up takes very little time and is well-documented on CircleCI's docs.
Specific language support: JavaScript

Yes

Automated code reviews are available for Javascript as well as specific documentation for setting up a Node.js project: https://scrutinizer-ci.com/docs/guides/javascript. Typescript is also supported.

Yes

For collecting test metadata and coverage, there is built-in support for Javascript. For code coverage, CircleCI understands Istanbul output (Jest also uses Istanbul for the code coverage reports), while for test metadata, the JUnit output format is natively supported.
Integrations
1st party support for common tools (like Slack notifications, various VCS platforms, etc)

Yes

Light integration with third party systems, mainly code management frameworks like GitHub, Bitbucket, GitLab.

Yes

Available as CircleCI Orbs: https://circleci.com/orbs/
API
Custom integreation is available, via an API or otherwise, it's mentioned separately as it allows further customization than any of the Ecosystem/Integration options

Yes

Comprehensive REST API available: https://scrutinizer-ci.com/docs/api/

Yes

REST API documentation available at https://circleci.com/docs/api/#api-overview. Creating Orbs is also documented at https://circleci.com/docs/2.0/orb-author/#introduction
Auditing

N/A

Unclear from the documentation, but most likely available.

N/A

Additional notes

The code analysis features seem great, the offer for similar tools is quite light. Seems similar to lgtm.com

How to run parallel tests on Scrutinizer CI and Circle CI
to execute 1-hour test suite in 2 minutes?

How it works

1. Install Knapsack Pro client in your project


2. Add Knapsack Pro client to your current CI server and run your tests in parallel



3. Update your CI server config file to run tests in parallel with Knapsack Pro

Knapsack Pro in Queue Mode will split tests in a dynamic way across parallel CI nodes to ensure each CI node finish work at a similar time. Thanks to that your CI build time is as fast as possible. It works with many supported CI servers.

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Get faster feedback from Scrutinizer CI and Circle CI server

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How to get faster Circle CI builds with dynamic test suite split instead of deterministic split

How to split E2E tests on multiple CI nodes using Cypress.io test runner

Jest JavaScript Testing and CI parallelisation how to do it?

Circle CI parallelism integration

Introduction to CI parallelisation with Knapsack Pro

Run tests in parallel on Scrutinizer CI and Circle CI in optimal way and avoid bottleneck parallel jobs.

How much can you save with faster tests
on Scrutinizer CI and Circle CI?

minutes
$

Monthly you can save hours
and up to $
on faster development cycle.

Features that make your tests perform better

  • Queue mode see video

    Dynamic tests allocation across Scrutinizer CI and Circle CI parallel jobs. Autobalance tests to get optimal test suite split betweeen CI nodes.

  • Regular mode see video

    Test suite split based on time execution. Generates subset of test suite per CI node before running tests.

  • Fallback mode

    Network issues? Not a problem, run tests anyway! Auto switch to the fallback mode to not depend on Knapsack Pro API.

  • All supported test runners

    Ruby: RSpec, Minitest, Test::Unit, Cucumber, Spinach, Turnip.

    JavaScript: Cypress.io, Jest

    Do you use different programming language or test runner? Let us know in the poll

Discover all features or see
how to use Knapsack Pro with your CI

Trusted solution

Join the teams optimizing their tests with Knapsack Pro.

We've been really enjoying Knapsack Pro, it's been saving us a ton of time.

Devin Brown Software Engineer at Pivotal

This is a fantastic product, it's been a total game-changer for us.

Geoff Harcourt CTO at CommonLit

We are using CircleCI and we noticed that builds were being limited by the slowest parallelized container. Knapsack Pro was really east to setup and we saw huge improvements right away. Thank you for making this tool!

Martin Sieniawski Software Engineer at Collage

Knapsack Pro has helped us build an insanely fast and scaleable build pipeline with almost no setup or maintenance.

Tim Lucas Co-founder of buildkite.com

Knapsack Pro saves us hours of engineer waiting time every week, and is the best solution for keeping our tests load balanced that we've used to date.

Michael Amygdalidis Senior Software Engineer at Popular Pays

I just logged into my account expecting it to say that I needed to add a credit card and was so surprised and delighted to see the trial doesn't count usage by calendar days but by testing days! This is incredible! I love it!!!

I just wanted to say that I really appreciate that small but very huge feature. Thank you for being so thoughtful :)

Shannon Baffoni Senior Software Engineer
at Blue Bottle Coffee

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