diff --git a/pkg/index.d.ts b/pkg/index.d.ts
index 2be4cce..c8b5b3f 100644
--- a/pkg/index.d.ts
+++ b/pkg/index.d.ts
@@ -109,6 +109,16 @@ export type Message =
       }
     >
   | BaseMessage<'DEPRECATED_FIELD_JSNEXT'>
+  | BaseMessage<
+      'INVALID_REPOSITORY_VALUE',
+      {
+        type:
+          | 'invalid-string-shorthand'
+          | 'invalid-git-url'
+          | 'deprecated-github-git-protocol'
+          | 'shorthand-git-sites'
+      }
+    >
 
 export interface Options {
   /**
diff --git a/pkg/src/index.js b/pkg/src/index.js
index b78765f..6e5462e 100755
--- a/pkg/src/index.js
+++ b/pkg/src/index.js
@@ -22,7 +22,11 @@ import {
   getPkgPathValue,
   replaceLast,
   isRelativePath,
-  isAbsolutePath
+  isAbsolutePath,
+  isGitUrl,
+  isShorthandRepositoryUrl,
+  isShorthandGitHubOrGitLabUrl,
+  isDeprecatedGitHubGitUrl
 } from './utils.js'
 
 /**
@@ -234,6 +238,12 @@ export async function publint({ pkgDir, vfs, level, strict, _packedFiles }) {
     }
   }
 
+  // if `repository` field exist, check if the value is valid
+  // `repository` might be a shorthand string of URL or an object
+  if ('repository' in rootPkg) {
+    promiseQueue.push(() => checkRepositoryField(rootPkg.repository))
+  }
+
   // check file existence for other known package fields
   const knownFields = [
     'types',
@@ -436,6 +446,55 @@ export async function publint({ pkgDir, vfs, level, strict, _packedFiles }) {
     }
   }
 
+  // https://docs.npmjs.com/cli/v10/configuring-npm/package-json#repository
+  /**
+   * @param {Record<string, string> | string} repository
+   */
+  async function checkRepositoryField(repository) {
+    if (!ensureTypeOfField(repository, ['string', 'object'], ['repository']))
+      return
+
+    if (typeof repository === 'string') {
+      // the string field accepts shorthands only. if this doesn't look like a shorthand,
+      // and looks like a git URL, recommend using the object form.
+      if (!isShorthandRepositoryUrl(repository)) {
+        messages.push({
+          code: 'INVALID_REPOSITORY_VALUE',
+          args: { type: 'invalid-string-shorthand' },
+          path: ['repository'],
+          type: 'warning'
+        })
+      }
+    } else if (
+      typeof repository === 'object' &&
+      repository.url &&
+      repository.type === 'git'
+    ) {
+      if (!isGitUrl(repository.url)) {
+        messages.push({
+          code: 'INVALID_REPOSITORY_VALUE',
+          args: { type: 'invalid-git-url' },
+          path: ['repository', 'url'],
+          type: 'warning'
+        })
+      } else if (isDeprecatedGitHubGitUrl(repository.url)) {
+        messages.push({
+          code: 'INVALID_REPOSITORY_VALUE',
+          args: { type: 'deprecated-github-git-protocol' },
+          path: ['repository', 'url'],
+          type: 'suggestion'
+        })
+      } else if (isShorthandGitHubOrGitLabUrl(repository.url)) {
+        messages.push({
+          code: 'INVALID_REPOSITORY_VALUE',
+          args: { type: 'shorthand-git-sites' },
+          path: ['repository', 'url'],
+          type: 'suggestion'
+        })
+      }
+    }
+  }
+
   /**
    * @param {string[]} pkgPath
    */
diff --git a/pkg/src/message.js b/pkg/src/message.js
index 704c561..e0eb81b 100644
--- a/pkg/src/message.js
+++ b/pkg/src/message.js
@@ -158,6 +158,32 @@ export function formatMessage(m, pkg) {
     case 'DEPRECATED_FIELD_JSNEXT':
       // prettier-ignore
       return `${c.bold(fp(m.path))} is deprecated. ${c.bold('pkg.module')} should be used instead.`
+    case 'INVALID_REPOSITORY_VALUE':
+      switch (m.args.type) {
+        case 'invalid-string-shorthand':
+          // prettier-ignore
+          return `${c.bold(fp(m.path))} is ${c.bold(pv(m.path))} which isn't a valid shorthand value supported by npm. Consider using an object that references a repository.`
+        case 'invalid-git-url':
+          // prettier-ignore
+          return `${c.bold(fp(m.path))} is ${c.bold(pv(m.path))} which isn't a valid git URL. A valid git URL is usually in the form of "${c.bold('git+https://example.com/user/repo.git')}".`
+        case 'deprecated-github-git-protocol':
+          // prettier-ignore
+          return `${c.bold(fp(m.path))} is ${c.bold(pv(m.path))} which uses the git:// protocol that is deprecated by GitHub due to security concerns. Consider replacing the protocol with https://.`
+        case 'shorthand-git-sites': {
+          let fullUrl = pv(m.path)
+          if (fullUrl[fullUrl.length - 1] === '/') {
+            fullUrl = fullUrl.slice(0, -1)
+          }
+          if (!fullUrl.startsWith('git+')) {
+            fullUrl = 'git+' + fullUrl
+          }
+          if (!fullUrl.endsWith('.git')) {
+            fullUrl += '.git'
+          }
+          // prettier-ignore
+          return `${c.bold(fp(m.path))} is ${c.bold(pv(m.path))} but could be a full git URL like "${c.bold(fullUrl)}".`
+        }
+      }
     default:
       return
   }
diff --git a/pkg/src/utils.js b/pkg/src/utils.js
index 64d15e7..39c9913 100644
--- a/pkg/src/utils.js
+++ b/pkg/src/utils.js
@@ -6,6 +6,7 @@ import { lintableFileExtensions } from './constants.js'
  *   main: string,
  *   module: string,
  *   exports: Record<string, string>,
+ *   repository: Record<string, string> | string,
  *   type: 'module' | 'commonjs'
  * }} Pkg
  */
@@ -45,6 +46,59 @@ export function stripComments(code) {
     .replace(SINGLELINE_COMMENTS_RE, '')
 }
 
+// Reference: https://git-scm.com/docs/git-clone#_git_urls and https://github.com/npm/hosted-git-info
+const GIT_URL_RE =
+  /^(git\+https?|git\+ssh|https?|ssh|git):\/\/(?:[\w._-]+@)?([\w.-]+)(?::([\w\d-]+))?(\/[\w._/-]+)\/?$/
+/**
+ * @param {string} url
+ */
+export function isGitUrl(url) {
+  return GIT_URL_RE.test(url)
+}
+/**
+ * @param {string} url
+ */
+export function isShorthandGitHubOrGitLabUrl(url) {
+  const tokens = url.match(GIT_URL_RE)
+  if (tokens) {
+    const host = tokens[2]
+    const path = tokens[4]
+
+    if (/(github|gitlab)/.test(host)) {
+      return !url.startsWith('git+') || !path.endsWith('.git')
+    }
+  }
+
+  return false
+}
+/**
+ * Reference: https://github.blog/security/application-security/improving-git-protocol-security-github/
+ * @param {string} url
+ */
+export function isDeprecatedGitHubGitUrl(url) {
+  const tokens = url.match(GIT_URL_RE)
+  if (tokens) {
+    const protocol = tokens[1]
+    const host = tokens[2]
+
+    if (/github/.test(host) && protocol === 'git') {
+      return true
+    }
+  }
+
+  return false
+}
+
+// Reference: https://docs.npmjs.com/cli/v10/configuring-npm/package-json#repository
+const SHORTHAND_REPOSITORY_URL_RE =
+  /^(?:(?:github|bitbucket|gitlab):[\w\-]+\/[\w\-]+|gist:\w+|[\w\-]+\/[\w\-]+)$/
+/**
+ * @param {string} url
+ */
+export function isShorthandRepositoryUrl(url) {
+  return SHORTHAND_REPOSITORY_URL_RE.test(url)
+}
+
 /**
  * @param {string} code
  * @returns {CodeFormat}
diff --git a/pkg/tests/fixtures/invalid-field-types/package.json b/pkg/tests/fixtures/invalid-field-types/package.json
index aaa9be7..4a34416 100644
--- a/pkg/tests/fixtures/invalid-field-types/package.json
+++ b/pkg/tests/fixtures/invalid-field-types/package.json
@@ -5,5 +5,6 @@
   "type": "commonjs",
   "main": 0,
   "module": true,
-  "jsnext:main": false
+  "jsnext:main": false,
+  "repository": 123
 }
\ No newline at end of file
diff --git a/pkg/tests/fixtures/invalid-repository-value-object-deprecated/package.json b/pkg/tests/fixtures/invalid-repository-value-object-deprecated/package.json
new file mode 100644
index 0000000..6d2b8ee
--- /dev/null
+++ b/pkg/tests/fixtures/invalid-repository-value-object-deprecated/package.json
@@ -0,0 +1,9 @@
+{
+    "name": "publint-invalid-repository-value-object-deprecatec",
+    "version": "0.0.1",
+    "type": "commonjs",
+    "repository": {
+      "type": "git",
+      "url": "git://www.github.com/bluwy/publint"
+    }
+  }
diff --git a/pkg/tests/fixtures/invalid-repository-value-object-not-git-url/package.json b/pkg/tests/fixtures/invalid-repository-value-object-not-git-url/package.json
new file mode 100644
index 0000000..a0b4b73
--- /dev/null
+++ b/pkg/tests/fixtures/invalid-repository-value-object-not-git-url/package.json
@@ -0,0 +1,9 @@
+{
+    "name": "publint-invalid-repository-value-object-not-git-url",
+    "version": "0.0.1",
+    "type": "commonjs",
+    "repository": {
+      "type": "git",
+      "url": "imap://fake.com/"
+    }
+  }
diff --git a/pkg/tests/fixtures/invalid-repository-value-object-shorthand-site/package.json b/pkg/tests/fixtures/invalid-repository-value-object-shorthand-site/package.json
new file mode 100644
index 0000000..7d300b4
--- /dev/null
+++ b/pkg/tests/fixtures/invalid-repository-value-object-shorthand-site/package.json
@@ -0,0 +1,9 @@
+{
+    "name": "publint-invalid-repository-value-object-shorthand-site",
+    "version": "0.0.1",
+    "type": "commonjs",
+    "repository": {
+      "type": "git",
+      "url": "https://www.github.com/bluwy/publint"
+    }
+  }
diff --git a/pkg/tests/fixtures/invalid-repository-value-shorthand/package.json b/pkg/tests/fixtures/invalid-repository-value-shorthand/package.json
new file mode 100644
index 0000000..f4c83a4
--- /dev/null
+++ b/pkg/tests/fixtures/invalid-repository-value-shorthand/package.json
@@ -0,0 +1,6 @@
+{
+    "name": "publint-invalid-repository-value-shorthand",
+    "version": "0.0.1",
+    "type": "commonjs",
+    "repository": "npm/npm"
+  }
diff --git a/pkg/tests/fixtures/invalid-repository-value-string-not-url/package.json b/pkg/tests/fixtures/invalid-repository-value-string-not-url/package.json
new file mode 100644
index 0000000..c1ae5db
--- /dev/null
+++ b/pkg/tests/fixtures/invalid-repository-value-string-not-url/package.json
@@ -0,0 +1,6 @@
+{
+    "name": "publint-invalid-repository-value-string-not-url",
+    "version": "0.0.1",
+    "type": "commonjs",
+    "repository": "not_an_url"
+  }
diff --git a/pkg/tests/playground.js b/pkg/tests/playground.js
index ee5a093..a343e3d 100644
--- a/pkg/tests/playground.js
+++ b/pkg/tests/playground.js
@@ -26,6 +26,7 @@ testFixture('glob-deprecated', [
 ])
 
 testFixture('invalid-field-types', [
+  'FIELD_INVALID_VALUE_TYPE',
   'FIELD_INVALID_VALUE_TYPE',
   'FIELD_INVALID_VALUE_TYPE',
   'FIELD_INVALID_VALUE_TYPE'
@@ -144,6 +145,36 @@ testFixture('deprecated-fields', [
   'USE_TYPE'
 ])
 
+testFixture('invalid-repository-value-string-not-url', [
+  {
+    code: 'INVALID_REPOSITORY_VALUE',
+    type: 'warning'
+  }
+])
+
+testFixture('invalid-repository-value-shorthand', [])
+
+testFixture('invalid-repository-value-object-not-git-url', [
+  {
+    code: 'INVALID_REPOSITORY_VALUE',
+    type: 'warning'
+  }
+])
+
+testFixture('invalid-repository-value-object-shorthand-site', [
+  {
+    code: 'INVALID_REPOSITORY_VALUE',
+    type: 'suggestion'
+  }
+])
+
+testFixture('invalid-repository-value-object-deprecated', [
+  {
+    code: 'INVALID_REPOSITORY_VALUE',
+    type: 'suggestion'
+  }
+])
+
 /**
  * @typedef {{
  *  level?: import('../index.d.ts').Options['level']
diff --git a/pkg/tests/utils.js b/pkg/tests/utils.js
index 46fe53c..a381c46 100644
--- a/pkg/tests/utils.js
+++ b/pkg/tests/utils.js
@@ -7,8 +7,12 @@ import {
   getCodeFormat,
   isCodeCjs,
   isCodeEsm,
+  isDeprecatedGitHubGitUrl,
   isFileContentLintable,
   isFilePathLintable,
+  isGitUrl,
+  isShorthandGitHubOrGitLabUrl,
+  isShorthandRepositoryUrl,
   stripComments
 } from '../src/utils.js'
 import { createNodeVfs } from '../src/vfs.js'
@@ -104,6 +108,64 @@ test('getCodeFormat', () => {
   }
 })
 
+test('isGitUrl', () => {
+  equal(isGitUrl('https://host.xz/path/to/repo.git/'), true)
+  equal(isGitUrl('http://host.xz/path/to/repo.git/'), true)
+  equal(isGitUrl('https://host.xz/path/to/repo.git'), true)
+  equal(isGitUrl('https://subdomain.host.xz/path/to/repo.git'), true)
+  equal(isGitUrl('https://192.168.0.1/path/to/repo.git'), true)
+  equal(isGitUrl('https://192.168.0.1:1234/path/to/repo.git'), true)
+  equal(isGitUrl('http://host.xz/path/to/repo.git'), true)
+  equal(isGitUrl('git+https://host.xz/path/to/repo.git'), true)
+  equal(isGitUrl('git+https://host.xz/path/to/repo'), true)
+  equal(isGitUrl('https://host.xz/path/to/repo.git'), true)
+  equal(isGitUrl('git+ssh://git@host.xz/path/to/repo.git'), true)
+  equal(isGitUrl('git+ssh://git@host.xz/path/to/repo'), true)
+  equal(isGitUrl('git+ssh://git@host.xz:1234/path/to/repo'), true)
+  equal(isGitUrl('git+ssh://host.xz:1234/path/to/repo'), true)
+  equal(isGitUrl('git://host.xz/path/to/repo.git'), true)
+  equal(isGitUrl('git://host.xz/path/to/repo'), true)
+  equal(isGitUrl('ssh://git@host.xz/user/project.git'), true)
+  equal(isGitUrl('ssh://git@host.xz:user/project.git'), true)
+  equal(isGitUrl('git+ssh://git@host.xz/user/project.git'), true)
+  equal(isGitUrl('git+ssh://git@host.xz:user/project.git'), true)
+  // NOTE: this technically works, but it's quite an edge case and technically not a URL,
+  // so maybe better to skip this and encourage proper URL format instead
+  // equal(isGitUrl('git@github.com:react-component/tooltip.git'), true)
+
+  equal(isGitUrl('file://host.xz/path/to/repo'), false)
+  equal(isGitUrl('/User/foo/bar'), false)
+})
+
+test('isDeprecatedGitHubGitUrl', () => {
+  equal(isDeprecatedGitHubGitUrl('git://github.com/user/project.git'), true)
+  equal(isDeprecatedGitHubGitUrl('https://github.com/user/project'), false)
+})
+
+test('isShorthandGitHubOrGitLabUrl', () => {
+  const f = isShorthandGitHubOrGitLabUrl // shorten to please prettier
+  equal(f('https://github.com/user/project'), true)
+  equal(f('git+https://github.com/user/project'), true)
+  equal(f('https://github.com/user/project.git'), true)
+  equal(f('https://gitlab.com/user/project'), true)
+  equal(f('git+https://gitlab.com/user/project'), true)
+  equal(f('https://gitlab.com/user/project.git'), true)
+
+  equal(f('https://bitbucket.com/user/project'), false)
+  equal(f('https://example.com'), false)
+})
+
+test('isShortHandRepositoryUrl', () => {
+  equal(isShorthandRepositoryUrl('user/project'), true)
+  equal(isShorthandRepositoryUrl('github:user/project'), true)
+  equal(isShorthandRepositoryUrl('gist:11081aaa281'), true)
+  equal(isShorthandRepositoryUrl('bitbucket:user/project'), true)
+  equal(isShorthandRepositoryUrl('gitlab:user/project'), true)
+
+  equal(isShorthandRepositoryUrl('foobar'), false)
+  equal(isShorthandRepositoryUrl('https://github.com/user/project'), false)
+})
+
 test('stripComments', () => {
   const result = stripComments(`
   // hello world
diff --git a/site/rules.md b/site/rules.md
index 9df1696..a0ce1d3 100644
--- a/site/rules.md
+++ b/site/rules.md
@@ -238,3 +238,23 @@ To fix this, you can rename `"./lib.server.js"` to `"./lib.worker.js"` for examp
 ## `DEPRECATED_FIELD_JSNEXT`
 
 The `"jsnext:main"` and `"jsnext"` fields are deprecated. The `"module"` field should be used instead. See [this issue](https://github.com/jsforum/jsforum/issues/5) for more information.
+
+## `INVALID_REPOSITORY_VALUE`
+
+`publint` is able to detect some cases where the `"repository"` field is not a valid and may not properly display on https://npmjs.com. The sub-rules below are mostly based on the [`"repository"` field docs](https://docs.npmjs.com/cli/v10/configuring-npm/package-json#repository).
+
+- If `"repository"` is a string, it must be one of the supported shorthand strings from the docs.
+- If `"repository"` is an object with `"type": "git"`, the `"url"` must be a valid [git URL](https://git-scm.com/docs/git-clone#_git_urls) and can be [parsed by npm](https://github.com/npm/hosted-git-info).
+- The `git://` protocol for GitHub repos should not be used due [security concerns](https://github.blog/security/application-security/improving-git-protocol-security-github/).
+- GitHub or GitLab links should be prefixed with `git+` and postfixed with `.git`. (This is also warned by npm when publishing a package).
+
+An example config that meets these criterias may look like this:
+
+```json
+{
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/bluwy/publint.git"
+  }
+}
+```
diff --git a/site/src/utils/message.js b/site/src/utils/message.js
index d22784b..ab2916d 100644
--- a/site/src/utils/message.js
+++ b/site/src/utils/message.js
@@ -100,8 +100,8 @@ function messageToString(m, pkg) {
       if (m.args.actualExtension && m.args.expectExtension) {
         // prettier-ignore
         return `The types is not exported. Consider adding ${bold(fp(m.path) + '.types')} to be compatible with TypeScript's ${bold('"moduleResolution": "bundler"')} compiler option. `
-            + `Note that you cannot use "${bold(typesFilePath)}" because it has a mismatching format. Instead, you can duplicate the file and use the ${bold(m.args.expectExtension)} extension, e.g. `
-            + `${bold(fp(m.path) + '.types')}: "${bold(replaceLast(typesFilePath,m.args.actualExtension, m.args.expectExtension))}"`
+          + `Note that you cannot use "${bold(typesFilePath)}" because it has a mismatching format. Instead, you can duplicate the file and use the ${bold(m.args.expectExtension)} extension, e.g. `
+          + `${bold(fp(m.path) + '.types')}: "${bold(replaceLast(typesFilePath, m.args.actualExtension, m.args.expectExtension))}"`
       } else {
         // prettier-ignore
         return `The types is not exported. Consider adding ${bold(fp(m.path) + '.types')}: "${bold(typesFilePath)}" to be compatible with TypeScript's ${bold('"moduleResolution": "bundler"')} compiler option.`
@@ -152,6 +152,32 @@ function messageToString(m, pkg) {
     case 'DEPRECATED_FIELD_JSNEXT':
       // prettier-ignore
       return `${bold(fp(m.path))} is deprecated. ${bold('pkg.module')} should be used instead.`
+    case 'INVALID_REPOSITORY_VALUE':
+      switch (m.args.type) {
+        case 'invalid-string-shorthand':
+          // prettier-ignore
+          return `The field value isn't a valid shorthand value supported by npm. Consider using an object that references a repository.`
+        case 'invalid-git-url':
+          // prettier-ignore
+          return `The field value isn't a valid git URL. A valid git URL is usually in the form of "${bold('git+https://example.com/user/repo.git')}".`
+        case 'deprecated-github-git-protocol':
+          // prettier-ignore
+          return `The field value uses the git:// protocol that is deprecated by GitHub due to security concerns. Consider replacing the protocol with https://.`
+        case 'shorthand-git-sites': {
+          let fullUrl = pv(m.path)
+          if (fullUrl[fullUrl.length - 1] === '/') {
+            fullUrl = fullUrl.slice(0, -1)
+          }
+          if (!fullUrl.startsWith('git+')) {
+            fullUrl = 'git+' + fullUrl
+          }
+          if (!fullUrl.endsWith('.git')) {
+            fullUrl += '.git'
+          }
+          // prettier-ignore
+          return `The field value could be a full git URL like "${bold(fullUrl)}".`
+        }
+      }
     default:
       return
   }