Continuous integration (CI) is a software development practice where multiple developers frequently integrate new code into a single software project. But when most people talk about CI, they’re actually referring to the automation of this process. In practice, continuous integration requires a CI system, which automatically builds, tests and verifies the code changes before they are integrated into the central repository. This allows multiple developers to push new code frequently without breaking anything or creating conflicts. CI is essential for catching bugs early, reducing delivery times, and improving overall software quality.

CI is one half of CI/CD, which stands for continuous integration and continuous deployment/delivery. In a nutshell, CI/CD is the end-to-end practice of automating as much of the manual effort as possible when getting new code from the developer’s machine into the user’s hands. As a result, teams are able to validate and ship updates fast and frequently.

We’ll go into more detail on the CI part of CI/CD below.

Continuous integration explained

Continuous integration (CI) is a development practice where developers frequently (at least daily) commit code changes in small batches to a shared version control repository. The viability of the new code is verified using automated checks.

CI is standard practice in basically all modern commercial software development. In a typical organization, after the research and product design phase, a team of developers is assigned to work on different features or functionalities. Each developer writes code for their assigned feature on their own branch (e.g., 2841-add-new-button-to-settings-page). When the code is ready, they’ll make a pull request (PR) to merge their code into the main development branch.

Obviously, developers need to check their code to make sure it actually works before merging. Doing this manually is a long process: developers would have to check out each code change locally, create a build, and run the tests on their laptop. This could take anywhere from 30–120 minutes, and in the meantime other developers may be pushing new code to the central branch, creating conflicts that can’t be detected locally.

This is where a CI system is absolutely essential. A CI system is an automation tool that triggers a CI pipeline whenever a developer opens a new PR. The pipeline is a series of tasks that build and test the software and confirm that the proposed new code does not contain any defects. This means developers can get feedback on the status of their code changes within a few minutes and do not have to waste valuable time manually running tests on their local machine.With a CI system in place, it’s easy to identify and fix defects, conflicts and other software quality issues before they ever get to production. This makes collaboration between developers much easier and faster, and ultimately leads to better quality software for the end-user.

Continuous integration pipeline

In practice, a CI process (pipeline) will typically look like the following:

Developers commit code
Developers regularly push their changes to a shared repository, often several times per day. New code from multiple contributors is continuously merged with the central codebase.

CI detects changes and builds
When code is committed, the CI system automatically triggers a build of the application to verify the changes. This ensures new code is integrated correctly and that the application remains in a deployable state.

Automated testing
Following the build, the CI system runs a series of automated tests to evaluate how the changes affect functionality, security, and policy compliance. Typical checks include unit and integration tests, security scans, and code-quality validations.

Feedback loop
CI delivers fast feedback to developers about whether their changes passed or failed, often within a few minutes. This means developers can quickly address bugs and quality issues, and iterate faster.

Code is merged
If the build and tests all succeed, the changes are merged into the main branch. Now everyone contributing to the project has access to the latest working version of the code.

What are the benefits of continuous integration?

Continuous integration is standard practice in modern software development, and absolutely essential when there are multiple developers working on a single software application. Even when dozens of developers are frequently merging code into a shared repository, each change is verified so the central codebase remains stable and functional. Automated build and test workflows to confirm new code integrates cleanly and doesn't break existing features. A strong CI system has a lot of downstream benefits for developer productivity, collaboration, and quality of the final product.

Small changes = stable codebase
‍CI encourages developers to work in small, manageable increments and share their changes regularly. Smaller commits make it easier to catch problems quickly, merges are faster and simpler, and overall keep the codebase more stable.

Quick fixes > expensive mistakes
CI enables teams to detect merge conflicts, bugs, and other defects right away. Finding problems early lowers the time and effort needed to fix them and prevents minor issues from growing into expensive failures.

Automation boosts productivity
‍Automating builds, tests, and integrations eliminates repetitive manual tasks and cuts down on human error. Developers can focus less on debugging and spend more time refining their code and developing high-quality features.

Short feedback loops = faster time-to-market
‍By shortening feedback loops and streamlining verification, CI enables teams to ship features fast and with confidence. Frequent releases help organizations react quickly to market needs and capture value sooner.

Improved collaboration and ownership
‍CI makes it much easier to collaborate, as individual developers always have access to the latest working version of the central repository and are frequently testing their code against it. This boosts coordination, knowledge transfer, and shared responsibility for the codebase, reducing miscommunications across the team.

Scalability and agility
‍CI supports scalability and adaptability as projects and teams expand. Even with dozens of developers pushing code every day, conflicts are quickly detected and resolved. It keeps integrations predictable and manageable, and fosters an iterative, agile approach to software development.

What are the best practices of continuous integration?

Whether you’re setting up your CI system for the first time or evolving an existing one, there are a few best practice principles to make sure your pipeline is fast and efficient.

1. CI as the foundation, with automated, fast feedback loops
   Implement CI as your foundation: every commit to the shared repo goes through an automated build and basic suite of tests. Keep tests quick, dependable, and clear so your team gets actionable feedback on what changes failed and why.
   

2. Repeatable delivery pipeline (build once, deploy many)
   Automate the entire path from build to deployment, including configuration, infrastructure provisioning, and database migrations. Produce a single, secure build artifact and reuse it across environments to avoid environment drift. Enforce a consistent release process so staging and production follow the same workflow, reducing deployment mistakes.
   

3. Test continuously and validate in production-like environments
   Integrate continuous testing across the pipeline: unit, integration, E2E, performance, and security tests at appropriate stages. Validate in production-like environments: mirror production infrastructure, data, and security rules in pre-prod to surface real-world issues early.
   

4. Infrastructure as code with versioning discipline
   Live and die by the use of version control: use it for application code, infrastructure, deployment scripts, and configuration in a VCS to maintain history, enable rollbacks, and improve collaboration. Manage database changes with discipline: version schemas and automate migrations (e.g. Flyway/Liquibase) so databases evolve safely as part of CI/CD.
   

5. Secure and observable pipelines
   Secure your pipeline end-to-end with secrets management, least-privilege access, up-to-date servers/plugins, plus SAST/DAST in the pipeline. Use tools to track and monitor your pipeline in real time, paying attention to build times, deployment status, and system health for early detection and measurement.
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6. Alignment and continuous improvement
   ‍Promote alignment across development, QA, security, and operations through shared docs, dashboards, and regular coordination. Use progressive delivery techniques (canary, blue/green, feature flags) to mitigate risk and enable controlled rollouts (and instant rollback). Embrace a mindset of continuous improvement: run retrospectives, experiment with tools and processes, and treat the pipeline as a product in its own right.

Continuous integration challenges and solutions

From cultural resistance to setting up the wrong tools, there are common challenges that can cause frustration for developers and easily undermine your CI implementation efforts. 

Continuous integration vs continuous delivery

On the surface, CI just means frequently merging code into a shared repository with automated builds and tests. But at its core, CI is the foundation of a stable codebase, and prevents “integration hell,” allowing developers to focus on progress instead of untangling complex conflicts.

There’s even more you can achieve when you combine continuous integration with continuous delivery, or even continuous deployment (CI/CD). CI concentrates on integrating code changes and preserving code quality through automated builds and tests. CD extends this by automating the release process so changes reach users faster. Here’s a quick breakdown of each term:

• ‍Continuous integration (CI) is the automated building and testing of frequent code commits.‍
• Continuous delivery (CD) automates moving successful changes to a pre-production environment. A human decision is still required to push them to users.‍
• Continuous deployment (also CD) fully automates all steps from build, to test, and deployment. If tests pass, each commit is deployed straight to production with no human intervention.

When you put everything together, you get CI/CD which streamlines and speeds up the entire development lifecycle from code changes through to production deployment.

Continuous integration with Bitrise

Bitrise CI is purpose-built for mobile development, eliminating the friction that comes with adapting generic CI platforms to iOS and Android workflows. Instead of cobbling together unmaintained plugins and writing custom scripts for basic mobile tasks, teams get native support for code signing, device testing, and platform-specific builds through 400+ curated Steps and visual workflow builders.

The platform handles infrastructure complexity automatically: Apple silicon machines (M2 Pro, M4 Pro) are optimized for mobile workloads, with same-day Xcode updates, pre-installed SDKs, and intelligent build orchestration that reduces unnecessary builds. Parallel pipelines and test sharding cut feedback loops from hours to minutes, while unified test reporting surfaces results, complete with screenshots and videos directly in your pull requests. Flaky test detection lets you flag and quarantine inconsistently failing tests so they don’t slow you down.

Most teams who try Bitrise get their first mobile build up-and-running in minutes, not days. The outcome: developers spend zero time maintaining CI infrastructure, build times drop, and mobile teams ship faster without needing dedicated DevOps expertise.