Coveralls vs LLVM llvm-cov

Coveralls analyzes software test coverage, showing teams which code is not covered by tests. Its dashboard presents project coverage percentages and their changes over time, while repository views drill down from a project to sub-projects, files, and individual lines. Build history tracks coverage across branches, including pull requests. Coveralls can add summarized coverage results to pull requests and send status updates that apply coverage criteria to merge decisions. Notifications can go to Slack or webhooks. It supports line and branch coverage, with report formats including LCOV, SimpleCov, Cobertura, JaCoCo, and Clover XML. Coveralls says it works with any CI service and lists more than 30 community-created integrations, a GitHub Action, and a CircleCI Orb. An API can add repositories programmatically and return recent build statistics. Open-source and public repositories are free. The Starter plan is $10 a month for one private repository and includes a 30-day trial. A self-hosted enterprise installation can operate within existing security controls without outbound network access.

LLVM llvm-cov is a free, self-hosted developer tool for examining coverage in instrumented C, C++, Objective-C, and Objective-C++ programs. It accepts executables, object files, dynamic libraries, or archives and works with gcov-style data or Clang instrumentation-based profiling. Its commands include gcov, show, report, and export. Show provides line-level coverage and can focus on selected source files. Report summarizes measurements such as branch, function, and MC/DC statistics; documented coverage types also include instantiation and region coverage. Output can be text, HTML, JSON, or LCOV. JSON exports may contain regions, functions, branches, expansions, and summaries. A typical workflow builds an instrumented program, runs it to create profile data, then uses llvm-profdata merge before analysis. The gcov command is compatible with gcov from GCC 4.2 and may work with later versions. LLVM documents llvm-cov as part of its developer toolchain. It runs on Linux, macOS, and Windows and has no paid plans or stated usage limits.