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

Circle CI

https://circleci.com

TeamCity

https://www.jetbrains.com/teamcity/
Unique feature

Premium Support

Technology awareness

Type of product

SaaS, Self-hosted / On Premise

On Premise

Offers a free plan

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.

Yes

They offer a great free professional plan, limited to 100 build configurations and 3 build agents. From there, you pay for each aditional agent you want (discounts if you purchase more than 1 agent at a time). They also provide a free plan for open source, non commercial projects, and steep 50% discounts for startups.
Predictable pricing

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)

Yes

They have a clear list of prices per number of agents.
Support / SLA

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.)

Yes

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

CircleCI can run builds in parallel, each build in a completely isolated environment by using containers.

Yes

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

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.

N/A

No specific mention that we could find, but judging by the wording used it would appear that tasks can be divided accross different machines.
Containers support / Build environment

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.

Yes

First class Docker support, among others
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

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

Yes

Great system overview, even allows building your own dashboards in order to see everything you're interested in at a glance.
Management support
How easy is it to manage users / projects / assign roles and permissions and so on

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).

Yes

Allows assigning roles, LDAP and Windows domain integrations and more.
Self-hosted option

Yes

Yes

Hosted plans / SaaS

Yes

No

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 in CircleCI are defined declaratively using an Yaml config file. CircleCI has special provisions for storing secrets in these files.

Yes

Unlike most options in the CI/CD space, TeamCity allows defining pipelines using a Kotlin-based DSL. This unlocks a lot of potential, such as templates for common CI/CD tasks, and deep integration with various IDEs (not just JetBrains IDEs)
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

Reports are available

Yes

Something that stands out from the rest, allows integrating third party reports, as long as they produce HTML output.
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 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/

Yes

JetBrains has a rich ecosystem of plugins in general.
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

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.

Yes

Using what they call 'Technology Awareness', promises great intehration with Ruby projects, with features such as testing framework support, static analysis and code coverage available out of the box, with no additional work required: https://www.jetbrains.com/teamcity/features/technology_awareness.html
Specific language support: JavaScript

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.

No (partial)

Unlike Ruby, there's no first class support for Javascript, although they do advertise the fact that their large collections of plugins can cover any use case for Javascript projects: https://plugins.jetbrains.com/teamcity
Integrations
1st party support for common tools (like Slack notifications, various VCS platforms, etc)

Yes

Available as CircleCI Orbs: https://circleci.com/orbs/

Yes

Great cloud integrations (Google Cloud, AWS, VMWare, etc) as well as 'key' integrations (VSCode, Jira, even NuGet)
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

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

Yes

Unlike most tools, which offer just a Rest API, TeamCity provides ample opportunity for extension via plugins, their own API, and service messages (formatted messages on stdout)
Auditing

N/A

Yes

Additional notes

Great ecosystem, with a strong focus on integration with other tools (not only JetBrains).

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

Without Knapsack Pro

you have to wait 20 minutes for slow tests running too long on red node

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Run fast parallel CI build with Knapsack Pro

CI build completes work in only 10 minutes because Knapsack Pro ensures all parallel nodes finish work at a similar time

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You can even run 20 parallel nodes to complete your CI build 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

Knapsack Pro how it works with CI server

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 Circle CI and TeamCity server

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Knapsack Pro terminal

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Circle CI parallelism integration

Introduction to CI parallelisation with Knapsack Pro

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

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

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 Circle CI and TeamCity 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've been playing with Queue Mode. Love it! Wow, I love how fast it goes.

Michael Menne CTO at humanagency.org

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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