diff --git a/packages/scripts/package.json b/packages/scripts/package.json
index 70862bf..960b582 100644
--- a/packages/scripts/package.json
+++ b/packages/scripts/package.json
@@ -14,4 +14,4 @@
   "types": "lib/index.d.ts",
   "devDependencies": {},
   "module": "lib/index.js"
-}
+}
\ No newline at end of file
diff --git a/packages/scripts/src/log.ts b/packages/scripts/src/log.ts
index ee76989..bcb150d 100644
--- a/packages/scripts/src/log.ts
+++ b/packages/scripts/src/log.ts
@@ -1,9 +1,9 @@
 import {format} from 'util'
 
 export function error(message: string, ...values: any[]) {
-  process.stderr.write(format(message + '\n', ...values))
+  process.stderr.write(format(message, ...values) + '\n')
 }
 
 export function info(message: string, ...values: any[]) {
-  process.stdout.write(format(message + '\n', ...values))
+  process.stdout.write(format(message, ...values) + '\n')
 }
diff --git a/packages/scripts/src/scripts/index.ts b/packages/scripts/src/scripts/index.ts
index 4238c24..f1e619b 100644
--- a/packages/scripts/src/scripts/index.ts
+++ b/packages/scripts/src/scripts/index.ts
@@ -3,3 +3,4 @@ export * from './build'
 export * from './exportDir'
 export * from './intergen'
 export * from './syncEsm'
+export * from './update'
diff --git a/packages/scripts/src/scripts/update.test.ts b/packages/scripts/src/scripts/update.test.ts
new file mode 100644
index 0000000..bb465d0
--- /dev/null
+++ b/packages/scripts/src/scripts/update.test.ts
@@ -0,0 +1,80 @@
+jest.mock('child_process')
+jest.mock('fs')
+jest.mock('../log')
+
+import cp from 'child_process'
+import * as fs from 'fs'
+import {update, IOutdated} from './update'
+
+describe('update', () => {
+
+  const stringify = (obj: object) => JSON.stringify(obj, null, '  ')
+
+  const readMock = fs.readFileSync as jest.Mock<typeof fs.readFileSync>
+  const writeMock = fs.writeFileSync as jest.Mock<typeof fs.writeFileSync>
+  const cpMock = cp.execFileSync as jest.Mock<typeof cp.execFileSync>
+
+  let outdated: Record<string, IOutdated> = {}
+  beforeEach(() => {
+    outdated = {}
+
+    cpMock.mockClear()
+    readMock.mockClear()
+    writeMock.mockClear()
+
+    cpMock.mockImplementation(() => {
+      const err = new Error('Exit code 1');
+      (err as any).stdout = stringify(outdated)
+      throw err
+    })
+    readMock.mockReturnValue(stringify({
+      name: 'test',
+      dependencies: {
+        a: '^1.2.3',
+      },
+      devDependencies: {
+        b: '^3.4.6',
+      },
+    }))
+  })
+
+  it('does not change when no changes', async () => {
+    cpMock.mockReturnValue('{}')
+    await update('update', '/my/dir')
+    expect(writeMock.mock.calls.length).toBe(0)
+  })
+
+  it('does not change when npm outdated output is empty', async () => {
+    cpMock.mockReturnValue('')
+    await update('update', '/my/dir')
+    expect(writeMock.mock.calls.length).toBe(0)
+  })
+
+  it('updates outdated dependencies in package.json', async () => {
+    outdated = {
+      a: {
+        wanted: '1.2.3',
+        latest: '1.4.0',
+        location: '',
+      },
+      b: {
+        wanted: '3.4.6',
+        latest: '3.4.7',
+        location: '',
+      },
+    }
+    await update('update', '/my/dir')
+    expect(writeMock.mock.calls).toEqual([[
+      '/my/dir/package.json', stringify({
+        name: 'test',
+        dependencies: {
+          a: '^1.4.0',
+        },
+        devDependencies: {
+          b: '^3.4.7',
+        },
+      }),
+    ]])
+  })
+
+})
diff --git a/packages/scripts/src/scripts/update.ts b/packages/scripts/src/scripts/update.ts
new file mode 100644
index 0000000..0cc5085
--- /dev/null
+++ b/packages/scripts/src/scripts/update.ts
@@ -0,0 +1,87 @@
+import * as fs from 'fs'
+import * as path from 'path'
+import cp from 'child_process'
+import {argparse, arg} from '@rondo.dev/argparse'
+import {info} from '../log'
+
+export interface IOutdated {
+  wanted: string
+  latest: string
+  location: string
+}
+
+export interface IPackage {
+  dependencies?: Record<string, string>
+  devDependencies?: Record<string, string>
+}
+
+function findOutdated(cwd: string): Record<string, IOutdated> {
+  try {
+    const result = cp.execFileSync('npm', ['outdated', '--json'], {
+      cwd,
+      encoding: 'utf8',
+    })
+    return result === '' ? {} : JSON.parse(result)
+  } catch (err) {
+    // npm outdated will exit with code 1 if there are outdated dependencies
+    return JSON.parse(err.stdout)
+  }
+}
+
+export async function update(...argv: string[]) {
+  const {parse} = argparse({
+    dirs: arg('string[]', {positional: true, default: ['.'], n: '+'}),
+    prefix: arg('string', {default: '^'}),
+  })
+  const {dirs, prefix} = parse(argv)
+
+  let updates = 0
+  for (const dir of dirs) {
+    info(dir)
+    const outdatedByName = findOutdated(dir)
+
+    const pkgFile = path.join(dir, 'package.json')
+    const pkg: IPackage = JSON.parse(fs.readFileSync(pkgFile, 'utf8'))
+    let pkgUpdate: IPackage = pkg
+
+    // tslint:disable-next-line
+    for (const name in outdatedByName) {
+      const outdated = outdatedByName[name]
+      pkgUpdate = updateDependency(
+        pkgUpdate, 'dependencies', name, prefix, outdated)
+      pkgUpdate = updateDependency(
+        pkgUpdate, 'devDependencies', name, prefix, outdated)
+    }
+
+    if (pkgUpdate !== pkg) {
+      updates += 1
+      info('Writing updates...')
+      fs.writeFileSync(pkgFile, JSON.stringify(pkgUpdate, null, '  '))
+    }
+  }
+
+  if (updates) {
+    info('Done! Do not forget to run npm install!')
+  }
+}
+
+function updateDependency(
+  pkg: IPackage,
+  key: 'dependencies' | 'devDependencies',
+  name: string,
+  prefix: string,
+  version: IOutdated,
+): IPackage {
+  const deps = pkg[key]
+  if (!deps || !deps[name] || version.wanted === version.latest) {
+    return pkg
+  }
+  info('  %s.%s %s ==> %s', key, name, version.wanted, version.latest)
+  return {
+    ...pkg,
+    [key]: {
+      ...deps,
+      [name]: prefix + version.latest,
+    },
+  }
+}