nyc
Code coverage tool built on istanbul for subprocesses.
Pricing
Free tier
Flat rate
Adoption
→StableLicense
Open Source
Data freshness
Aging · Jun 8, 2026Overview
What is nyc?
nyc is a code coverage tool that works with subprocesses and is built on top of Istanbul. It helps developers measure the effectiveness of their test suites by identifying which parts of the code are being tested and which are not.
Key differentiator
“nyc stands out as an open-source tool specifically designed to work seamlessly with subprocesses, offering detailed and accurate code coverage reports for JavaScript and TypeScript projects.”
Capability profile
Capability Radar
Honest assessment
Strengths & Weaknesses
↑ Strengths
↓ Weaknesses
nyc's configuration options and integration with test runners can be complex, requiring significant time to fully understand.
The official documentation focuses mainly on basic setup and usage but lacks detailed examples for more complex scenarios such as custom reporters or integrations with CI/CD pipelines.
nyc can introduce significant performance overhead, especially in large projects, which may slow down the test suite execution time.
Subprocess code coverage might not be accurately reported due to limitations in how nyc handles child processes and external modules.
Fit analysis
Who is it for?
✓ Best for
JavaScript and TypeScript projects needing detailed coverage reports.
Teams that require integration with subprocesses for accurate coverage analysis.
✕ Not a fit for
Projects requiring cloud-based code coverage services.
Developers looking for a web UI to manage their test coverage.
Cost structure
Pricing
Free Tier
Available
Open source — free to use
Starts at
$0
Model
Flat rate
Enterprise
None
Performance benchmarks
How Fast Is It?
Ecosystem
Relationships
Next step
Get Started with nyc
Step-by-step setup guide with code examples and common gotchas.