Jenkins vs Heroku CI comparison of Continuous Integration servers
What are the differences between Jenkins and Heroku CI?

Plugins

Heroku Flow

Self-hosted / On Premise

SaaS

Yes

Free, open source software

No (partial)

For CI only, the cost starts at $10 for pipeline, plus a variable amount depending on how long the build runs for (prorated per second). The servers used for CI cost $250 for a full month, which means you get about 3 hours for $1. For hosting, there's a free tier, limited to 1 web/1 worker with 512 MB RAM. One of the more annoying limitations is that free dynos are put into sleep mode after 30 min. of inactivity, which increases loading times considerably.

Yes

Jenkins is free software, the only costs are those assigned to running your infrastructure.

Yes

Clearly defined, offers a calculator.

No (partial)

No official support available, or SLAs. However, Jenkins' popularity ensures you'll find support in various places (official Jenkins forum, IRC, StackOverflow etc.)

Yes

Yes (partial)

Jenkins allows builds to be run in parallel, but all builds share the same environment and there can be issues arising from shared resources such as the filesystem.

Yes

Up to 16 nodes. You can ask Heroku support to enable up to 32 parallel dynos.

Yes (partial)

Jenkins has a concept of master server and agents, for distributing builds, but setting that up requires quite a bit of manual work from a sysadmin, compared to other options.

N/A

No (partial)

By default, Jenkins runs all builds in the same environment as the build server itself, which can lead to numerous issues and is generally not a good practice. Some plugins address this issue, but they need to be manually installed.

Yes

Builds run in isolation on new dynos (Heroku containers). Wide support via buildpacks: https://devcenter.heroku.com/articles/buildpacks

Yes

Available via the Blue Ocean project (part of Jenkins): https://jenkins.io/doc/book/blueocean/dashboard/#dashboard

Yes

Great visual overview built-in.

No

In practice, for Jenkins it usually means that there's someone solely in charge of the Jenkins instance (configuration, management). Collaboration features built into other similar products are lacking, as are governance features (no easy way to tell from Jenkins alone _who_ is responsabile for a broken build, for example), even if your Version Control Server of choice can give that information (via `git blame` for example).

Yes

One of the more mature solutions for teams on the market, Heroku Teams is available for free for 1-5 people, and comes at a cost for 6+ team members: https://www.heroku.com/pricing#team-comparison. Allows setting roles and app-level permissions with ease.

Yes

Jenkins is Open Source Software, and self-hosting is the only way to use it.

No

No

Only available for self-hosting.

Yes

Yes

Offers extensive support for custom pipelines, either through the Jenkins Pipeline DSL, written in a Jenkinsfile, either through the Web UI. Also, their Blue Ocean project is a great tool for building pipelines: https://jenkins.io/projects/blueocean/

Yes

Very easy and intuitive process that allows defining a pipeline from code commit, to code review (review apps), user acceptance testing and production deployment, via Heroku Flow. Works best if the project is also hosted on Heroku.

Yes

Has ready-made integrations for standard reports such as JUnit test results.

Yes

> 1000 community plugins

Thanks to it's popularity, there's a large selection of available plugins for Jenkins. They can all be easily browsed over at https://plugins.jenkins.io/. The downside is that almost anything you want to do in Jenkins requires installing a plugin, even core functionality such as parsing output or checking out source code.

Yes

Wide array of 3rd party add-ons available via Heroku Elements: https://elements.heroku.com/addons. Custom buildpacks are also available for almost any stack you might be using (over 5500 buildpacks available at the moment)

Yes (Partial)

RSpec and Cucumber test suites can be integrated into Jenkins thanks to the large pool of available plugins and Ruby gems. Jenkins only understands the JUnit format natively.

Yes

Although not specifically built in to Heroku, it's guaranteed that any Ruby specific need that might arise would be solved via add-ons, buildpacks or other integrations available.

Yes (Partial)

Jest, AVA and other test suites can be integrated into Jenkins thanks to the large pool of available plugins and NPM packages. Jenkins only understands the JUnit format natively.

Yes

Although not specifically built in to Heroku, it's guaranteed that any Javascript specific need that might arise would be solved via add-ons, buildpacks or other integrations available.

Yes

Allows integrations with other tools (ie: Slack, GitHub) or communication protocols (ie: email) via it's rich plugin suite

Yes

The strongest built-in integrations are with GitHub and Slack (ChatOps) but even allows integrating 3rd party CI servers in the workflow if you so require, among others.

Yes

For use-cases that the +1k plugins don't cover, the Jenkins Remote API is yet another way to integrate Jenkins into your favorite tools or internal products.

Yes

Offers a feature rich API that allows CRUD operations on the most important features, such as promoting an app to production, or inspecting a specific pipeline.

No

Jenkins instances are really managed by a sole user with administrative privileges. This can lead to various issues when it comes to audit trails / accountability.

Yes