What fields are required?

"name" and "version" are required by npm; description, license, repository and author are recommended.

Does it check dependency ranges?

Yes, it flags dependency version ranges that don't look like valid semver or git/URL specifiers.

Is my package.json sent anywhere?

No, validation happens entirely in your browser.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

Package.json Validator

Validate package.json fields, semver ranges, and scripts.

Support

Works Offline

Privacy First

No Login

No API

package.json

Paste your package.json contents

Validation results

Required fields, semver ranges, scripts

Errors

Warnings

Info

Recommended field "license" is missing.
Recommended field "repository" is missing.
Recommended field "author" is missing.
No blocking errors found.

Scripts

build→vite build
dev→vite

About the Package.json Validator

Paste a package.json file and check for missing required or recommended fields, invalid semver versions and dependency ranges, malformed scripts, and other common mistakes.

Examples

Missing version

{ "name": "app" }

Output

Error: missing required field "version"

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

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Version 1.0.0 · Updated 2026-08-06 · Runs entirely in your browser