Coveralls

Web-based code coverage service that tracks test coverage over time and highlights uncovered code. It integrates with CI pipelines to ingest coverage reports and surface file-by-file, line-by-line visibility so teams can see exactly where tests are lacking before issues reach production.

Coveralls is trusted by open source projects such as React, Express, Sentry, and GitLab. It stands out by working with any CI service and offering 30-plus community integrations across C, C++, Go, Haskell, Java, JavaScript, PHP, Python, R, Ruby, Scala, and more. The service maintains unlimited history for every build and branch, so teams can inspect coverage trends across the full development cycle.

Key capabilities:

• Coverage dashboard with aggregate stats, file trees, and line-by-line source views
• PR comments and status updates to gate merges based on coverage criteria
• Universal Coverage Reporter, a cross-platform binary for all coverage formats
• Official integrations with GitHub Actions and CircleCI Orb
• API for programmatic repo management and build stats
• Coverage badges and Slack or webhook notifications

Teams use Coveralls to enforce coverage standards in pull requests, discover untested code paths, and share coverage visibility across the organization. The CI-agnostic design and language integrations simplify adoption regardless of test framework or build system.