IconVault's Package.json Linter runs 25+ quality checks on your package.json and rolls them into an A-F grade. It validates the name against npm rules, checks the license is a valid SPDX identifier, inspects scripts, keywords, engines, repository, files, exports and dependency hygiene, and flags the mistakes that break installs or publishes.

Your package.json is parsed and checked locally in your browser: it is never uploaded, never sent anywhere and never stored. It is free with no signup, and a sample package.json is included so you can try it instantly. The honest caveat: this is a static checklist, not a build test. A passing grade means the manifest looks right, not that the package actually builds or runs.