# Developer first Code Coverage platform > Discover what untested code is causing errors & how to avoid similar errors in the future with Sentry's Codecov integration. Try Codecov for free. **URL:** https://sentry.io/product/code-coverage/ --- See the untested code causing errors - or whether it’s partially or fully covered - directly in your stack trace to avoid similar errors from happening in the future. ## Features ### See code coverage at every stage of development. Check and correct code coverage before release in your code host, and find it in the stack trace when things get real. ### View all your coverage in one place. Aggregate coverage reporting, see changes over time, and get cross-repo analytics so you have visibility across all your services. ### Group your testing concerns. Create custom statuses and group coverage in your repo without modifying your test setup using Flags and Components. ## Features - **Code Coverage**: Understand test coverage of code. — [Learn more](https://docs.codecov.com/docs/about-code-coverage) - **Coverage by Project**: Track coverage metrics for individual projects. — [Learn more](https://docs.codecov.com/docs/common-recipe-list#show-project-coverage-changes-on-the-pull-request-comment) - **Coverage by Change/Patch**: Monitor coverage with each code change. — [Learn more](https://docs.codecov.io/docs/patch-coverage/) - **PR Comments**: Feedback on pull requests with coverage insights. — [Learn more](https://docs.codecov.io/docs/github-checks/) - **Flags**: Define coverage requirements for projects. — [Learn more](https://docs.codecov.io/docs/flags/) ## FAQ **What do I need to do to see test coverage data in my Sentry issues?** You must be on a Sentry Team or Business plan - [check your Sentry plan subscription](https://sentry.io/settings/billing/overview/). Additionally, make sure you have Sentry’s GitHub integration installed and [Code Mappings](https://docs.sentry.io/product/issues/suspect-commits/#2-set-up-code-mappings) configured. This will help Sentry determine which source code files to fetch for coverage information. Codecov Requirements You must be an existing Codecov customer. If you’re not, [getting started](https://about.codecov.io/sign-up-sentry-codecov/) with Codecov takes a few minutes and you can try it for free for 14 days. [Sign up here](https://about.codecov.io/sign-up-sentry-codecov/). **What is code coverage and why does it matter?** There is a direct correlation between poor test coverage and incidents. Code coverage is a testing technique that informs what code is tested and what is not. It is often represented as a percentage of the number of lines of code tested versus the entire codebase. Without building these tests and having proper test coverage, it's easy to miss preventable bugs before shipping to production which impacts the user experience and can have your developers scrambling to find fixes. With code coverage solutions like Codecov, you can get a holistic view of your code coverage so you can do things like understand what code is covered when there are drops in code coverage. You can provide blocking status checks on PRs to prevent merging code that has not been well-tested so you and your team can build more reliable and secure code. To learn more, check out [Codecov's free ebook](https://about.codecov.io/resource/what-is-code-coverage/). ## Of course we have more content - [What is code coverage eBook](https://about.codecov.io/resource/what-is-code-coverage/): To get an understanding of code coverage, we have to talk about testing code. A test runs a piece of code and ensures that the system produces the expected behavior given some input. - [Codecov on-demand demo](https://about.codecov.io/codecov-get-demo/): Codecov is the all-in-one code coverage reporting solution for any test suite — giving developers actionable insights to deploy reliable code with confidence. - [Code coverage insights - now in your stack trace](https://blog.sentry.io/code-coverage-insights-now-in-your-stack-trace-announcing-our-codecov/): Using Codecov’s integration with Sentry allows you to see the untested code causing errors directly in the Sentry Issue stack trace. - [Bringing Codecov into the Sentry family: where code coverage meets application monitoring](https://blog.sentry.io/bringing-codecov-into-the-sentry-family-where-code-coverage-meets-application-monitoring/): Codecov makes coverage actionable for over two dozen test frameworks, and has helped over a million software developers improve their approach to testing, coverage, and code reliability. ## Testimonials > Codecov unifies coverage data in one place and visualizes the data very well. It also provides the API to query the data for analytics purposes. For our usage, it provides feedback on pull requests directly and nicely improves the developer experience to shorten the feedback loop so that they can fix their issues more quickly. > — Jun Li, Lyft > As we’ve created this positive feedback loop of increased coverage, it’s a reward for adding more test coverage. Maybe you’re not refactoring something, you’re just adding some functionality. You get to increase test coverage while paying off tech debt. > — Dave Bullock, UJET --- *Source: [sentry.io/product/code-coverage/](https://sentry.io/product/code-coverage/)*