diff --git a/packages/pinia/__tests__/devtools/utils.spec.ts b/packages/pinia/__tests__/devtools/utils.spec.ts
new file mode 100644
index 0000000000..cd1c3e787e
--- /dev/null
+++ b/packages/pinia/__tests__/devtools/utils.spec.ts
@@ -0,0 +1,275 @@
+import { describe, it, expect } from 'vitest'
+import { formatStateDifferences, realTypeOf } from '../../src/devtools/utils'
+
+describe('Devtools utils', () => {
+  describe('realTypeOf', () => {
+    it('Should correctly predict type of subject', () => {
+      const number = 0
+      const string = 'undefined'
+      const undefinedValue = undefined
+      const nullValue = null
+      const array: any[] = []
+      const date = new Date(123)
+      const object = {}
+      const regexp = /regexp/
+      const functionValue = () => {}
+
+      let type = realTypeOf(number)
+
+      expect(type).toEqual('number')
+
+      type = realTypeOf(string)
+
+      expect(type).toEqual('string')
+
+      type = realTypeOf(undefinedValue)
+
+      expect(type).toEqual('undefined')
+
+      type = realTypeOf(nullValue)
+
+      expect(type).toEqual('null')
+
+      type = realTypeOf(array)
+
+      expect(type).toEqual('array')
+
+      type = realTypeOf(date)
+
+      expect(type).toEqual('date')
+
+      type = realTypeOf(object)
+
+      expect(type).toEqual('object')
+
+      type = realTypeOf(regexp)
+
+      expect(type).toEqual('regexp')
+
+      type = realTypeOf(functionValue)
+
+      expect(type).toEqual('function')
+    })
+  })
+
+  describe('formatStateDifferences', () => {
+    it('Should find removed entries', () => {
+      const oldState = {
+        removed: 'old',
+      }
+      const newState = {}
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        removed: undefined,
+      })
+    })
+
+    it('Should find difference in array', () => {
+      const oldState = {
+        changedArray1: [1, 2, 3],
+        unchangedArray: [1, 2, 3],
+        changedArray2: [1, 2, 3],
+      }
+      const newState = {
+        changedArray1: [1, 2, 3, 4],
+        unchangedArray: [1, 2, 3],
+        changedArray2: [3, 2, 1],
+      }
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        changedArray1: [1, 2, 3, 4],
+        changedArray2: [3, 2, 1],
+      })
+    })
+
+    it('Should find difference in regexp', () => {
+      const oldState = {
+        changedRegexp: /changed/,
+        unchangedRegexp: /unchanged/,
+      }
+      const newState = {
+        changedRegexp: /changedToNewValue/,
+        unchangedRegexp: /unchanged/,
+      }
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        changedRegexp: /changedToNewValue/,
+      })
+    })
+
+    it('Should find difference in date', () => {
+      const oldState = {
+        changedDate: new Date(123),
+        unchangedDate: new Date(123),
+      }
+      const newState = {
+        changedDate: new Date(1234),
+        unchangedDate: new Date(123),
+      }
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        changedDate: new Date(1234),
+      })
+    })
+
+    it('Should find difference in booleans', () => {
+      const oldState = {
+        changedBool: true,
+        unchangedBool: true,
+      }
+      const newState = {
+        changedBool: false,
+        unchangedBool: true,
+      }
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        changedBool: false,
+      })
+    })
+
+    it('Should find difference in numbers', () => {
+      const oldState = {
+        changedNumber: 10,
+        unchangedNumber: 10,
+      }
+      const newState = {
+        changedNumber: 9,
+        unchangedNumber: 10,
+      }
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        changedNumber: 9,
+      })
+    })
+
+    it('Should find difference in strings', () => {
+      const oldState = {
+        changedString: 'changed',
+        unchangedString: 'unchanged',
+      }
+      const newState = {
+        changedString: 'changedToNewValue',
+        unchangedString: 'unchanged',
+      }
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        changedString: 'changedToNewValue',
+      })
+    })
+
+    it('Should find new values', () => {
+      const oldState = {}
+      const newState = {
+        newValue: 10,
+      }
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        newValue: 10,
+      })
+    })
+
+    it('Should correctly see changes deep in objects', () => {
+      const oldState = {
+        changedObject: {
+          key1: 'unchanged',
+          key2: {
+            key1: {
+              key1: {
+                key1: false,
+                key2: true,
+              },
+            },
+          },
+          key3: {
+            key1: {
+              key1: {},
+            },
+            key2: {
+              key1: 'abc',
+            },
+          },
+          key4: 50,
+        },
+      }
+      const newState = {
+        changedObject: {
+          key1: 'unchanged',
+          key2: {
+            key1: {
+              key1: {
+                key1: true,
+                key2: true,
+              },
+            },
+          },
+          key3: {
+            key1: {
+              key1: {},
+            },
+            key2: {
+              key1: 'abcd',
+            },
+          },
+          key4: 50,
+        },
+      }
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        changedObject: {
+          key2: {
+            key1: {
+              key1: {
+                key1: true,
+              },
+            },
+          },
+          key3: {
+            key2: {
+              key1: 'abcd',
+            },
+          },
+        },
+      })
+    })
+
+    it('Should find the difference between functions', () => {
+      const foo = () => {}
+      const bar = () => {}
+      const foobar = () => {}
+
+      const oldState = {
+        foo,
+        bar,
+      }
+
+      const newState = {
+        foo: foobar,
+        bar,
+      }
+
+      const differences = formatStateDifferences(oldState, newState)
+
+      expect(differences).toEqual({
+        foo: foobar,
+      })
+    })
+  })
+})
diff --git a/packages/pinia/src/devtools/fastCopy.ts b/packages/pinia/src/devtools/fastCopy.ts
new file mode 100644
index 0000000000..780f7a241b
--- /dev/null
+++ b/packages/pinia/src/devtools/fastCopy.ts
@@ -0,0 +1,408 @@
+// Clone deep utility for cloning state of the store
+// Forked from https://github.com/planttheidea/fast-copy
+// Last update: 24-08-2022
+
+declare namespace FastCopy {
+  export type Realm = Record<string, any>
+
+  export interface Cache {
+    _keys?: any[]
+    _values?: any[]
+    has: (value: any) => boolean
+    set: (key: any, value: any) => void
+    get: (key: any) => any
+  }
+
+  export type Copier = <Value = any>(value: Value, cache: Cache) => Value
+
+  export type ObjectCloner = <Value>(
+    object: Value,
+    realm: Realm,
+    handleCopy: Copier,
+    cache: Cache
+  ) => Value
+
+  export type Options = {
+    isStrict?: boolean
+    realm?: Realm
+  }
+}
+
+const { toString: toStringFunction } = Function.prototype
+const {
+  create,
+  defineProperty,
+  getOwnPropertyDescriptor,
+  getOwnPropertyNames,
+  getOwnPropertySymbols,
+  getPrototypeOf,
+} = Object
+
+const SYMBOL_PROPERTIES = typeof getOwnPropertySymbols === 'function'
+const WEAK_MAP = typeof WeakMap === 'function'
+
+/**
+ * @function createCache
+ *
+ * @description
+ * get a new cache object to prevent circular references
+ *
+ * @returns the new cache object
+ */
+export const createCache = (() => {
+  if (WEAK_MAP) {
+    return (): FastCopy.Cache => new WeakMap()
+  }
+
+  class Cache {
+    _keys: any[] = []
+    _values: any[] = []
+
+    has(key: any) {
+      return !!~this._keys.indexOf(key)
+    }
+
+    get(key: any) {
+      return this._values[this._keys.indexOf(key)]
+    }
+
+    set(key: any, value: any) {
+      this._keys.push(key)
+      this._values.push(value)
+    }
+  }
+
+  return (): FastCopy.Cache => new Cache()
+})()
+
+/**
+ * @function getCleanClone
+ *
+ * @description
+ * get an empty version of the object with the same prototype it has
+ *
+ * @param object the object to build a clean clone from
+ * @param realm the realm the object resides in
+ * @returns the empty cloned object
+ */
+export const getCleanClone = (object: any, realm: FastCopy.Realm): any => {
+  const prototype = object.__proto__ || getPrototypeOf(object)
+
+  if (!prototype) {
+    return create(null)
+  }
+
+  const Constructor = prototype.constructor
+
+  if (Constructor === realm.Object) {
+    return prototype === realm.Object.prototype ? {} : create(prototype)
+  }
+
+  if (~toStringFunction.call(Constructor).indexOf('[native code]')) {
+    try {
+      return new Constructor()
+    } catch {}
+  }
+
+  return create(prototype)
+}
+
+/**
+ * @function getObjectCloneStrict
+ *
+ * @description
+ * get a copy of the object based on strict rules, meaning all keys and symbols
+ * are copied based on the original property descriptors
+ *
+ * @param object the object to clone
+ * @param realm the realm the object resides in
+ * @param handleCopy the function that handles copying the object
+ * @returns the copied object
+ */
+export const getObjectCloneStrict: FastCopy.ObjectCloner = (
+  object: any,
+  realm: FastCopy.Realm,
+  handleCopy: FastCopy.Copier,
+  cache: FastCopy.Cache
+): any => {
+  const clone: any = getCleanClone(object, realm)
+
+  // set in the cache immediately to be able to reuse the object recursively
+  cache.set(object, clone)
+
+  const properties: (string | symbol)[] = SYMBOL_PROPERTIES
+    ? getOwnPropertyNames(object).concat(
+        getOwnPropertySymbols(object) as unknown as string[]
+      )
+    : getOwnPropertyNames(object)
+
+  for (
+    let index = 0, length = properties.length, property, descriptor;
+    index < length;
+    ++index
+  ) {
+    property = properties[index]
+
+    if (property !== 'callee' && property !== 'caller') {
+      descriptor = getOwnPropertyDescriptor(object, property)
+
+      if (descriptor) {
+        // Only clone the value if actually a value, not a getter / setter.
+        if (!descriptor.get && !descriptor.set) {
+          descriptor.value = handleCopy(object[property], cache)
+        }
+
+        try {
+          defineProperty(clone, property, descriptor)
+        } catch (error) {
+          // Tee above can fail on node in edge cases, so fall back to the loose assignment.
+          clone[property] = descriptor.value
+        }
+      } else {
+        // In extra edge cases where the property descriptor cannot be retrived, fall back to
+        // the loose assignment.
+        clone[property] = handleCopy(object[property], cache)
+      }
+    }
+  }
+
+  return clone
+}
+
+/**
+ * @function getRegExpFlags
+ *
+ * @description
+ * get the flags to apply to the copied regexp
+ *
+ * @param regExp the regexp to get the flags of
+ * @returns the flags for the regexp
+ */
+export const getRegExpFlags = (regExp: RegExp): string => {
+  let flags = ''
+
+  if (regExp.global) {
+    flags += 'g'
+  }
+
+  if (regExp.ignoreCase) {
+    flags += 'i'
+  }
+
+  if (regExp.multiline) {
+    flags += 'm'
+  }
+
+  if (regExp.unicode) {
+    flags += 'u'
+  }
+
+  if (regExp.sticky) {
+    flags += 'y'
+  }
+
+  return flags
+}
+
+const { isArray } = Array
+
+const GLOBAL_THIS: FastCopy.Realm = (function () {
+  if (typeof globalThis !== 'undefined') {
+    return globalThis
+  }
+
+  if (typeof self !== 'undefined') {
+    return self
+  }
+
+  if (typeof window !== 'undefined') {
+    return window
+  }
+
+  if (typeof global !== 'undefined') {
+    return global
+  }
+
+  if (console && console.error) {
+    console.error('Unable to locate global object, returning "this".')
+  }
+
+  // @ts-ignore
+  return this
+})()
+
+/**
+ * @function copy
+ *
+ * @description
+ * copy an value deeply as much as possible
+ *
+ * If `strict` is applied, then all properties (including non-enumerable ones)
+ * are copied with their original property descriptors on both objects and arrays.
+ *
+ * The value is compared to the global constructors in the `realm` provided,
+ * and the native constructor is always used to ensure that extensions of native
+ * objects (allows in ES2015+) are maintained.
+ *
+ * @param value the value to copy
+ * @param [options] the options for copying with
+ * @param [options.isStrict] should the copy be strict
+ * @param [options.realm] the realm (this) value the value is copied from
+ * @returns the copied value
+ */
+function copy<Value>(value: Value, options?: FastCopy.Options): Value {
+  // manually coalesced instead of default parameters for performance
+  const realm = (options && options.realm) || GLOBAL_THIS
+  const getObjectClone = getObjectCloneStrict
+
+  /**
+   * @function handleCopy
+   *
+   * @description
+   * copy the value recursively based on its type
+   *
+   * @param value the value to copy
+   * @returns the copied value
+   */
+  const handleCopy: FastCopy.Copier = (
+    value: any,
+    cache: FastCopy.Cache
+  ): any => {
+    if (!value || typeof value !== 'object') {
+      return value
+    }
+
+    if (cache.has(value)) {
+      return cache.get(value)
+    }
+
+    const prototype = value.__proto__ || getPrototypeOf(value)
+    const Constructor = prototype && prototype.constructor
+
+    // plain objects
+    if (!Constructor || Constructor === realm.Object) {
+      return getObjectClone(value, realm, handleCopy, cache)
+    }
+
+    let clone: any
+
+    // arrays
+    if (isArray(value)) {
+      return getObjectCloneStrict(value, realm, handleCopy, cache)
+    }
+
+    // dates
+    if (value instanceof realm.Date) {
+      return new Constructor(value.getTime())
+    }
+
+    // regexps
+    if (value instanceof realm.RegExp) {
+      clone = new Constructor(
+        value.source,
+        value.flags || getRegExpFlags(value)
+      )
+
+      clone.lastIndex = value.lastIndex
+
+      return clone
+    }
+
+    // maps
+    if (realm.Map && value instanceof realm.Map) {
+      clone = new Constructor()
+      cache.set(value, clone)
+
+      value.forEach((value: any, key: any) => {
+        clone.set(key, handleCopy(value, cache))
+      })
+
+      return clone
+    }
+
+    // sets
+    if (realm.Set && value instanceof realm.Set) {
+      clone = new Constructor()
+      cache.set(value, clone)
+
+      value.forEach((value: any) => {
+        clone.add(handleCopy(value, cache))
+      })
+
+      return clone
+    }
+
+    // blobs
+    if (realm.Blob && value instanceof realm.Blob) {
+      return value.slice(0, value.size, value.type)
+    }
+
+    // buffers (node-only)
+    if (realm.Buffer && realm.Buffer.isBuffer(value)) {
+      clone = realm.Buffer.allocUnsafe
+        ? realm.Buffer.allocUnsafe(value.length)
+        : new Constructor(value.length)
+
+      cache.set(value, clone)
+      value.copy(clone)
+
+      return clone
+    }
+
+    // arraybuffers / dataviews
+    if (realm.ArrayBuffer) {
+      // dataviews
+      if (realm.ArrayBuffer.isView(value)) {
+        clone = new Constructor(value.buffer.slice(0))
+        cache.set(value, clone)
+        return clone
+      }
+
+      // arraybuffers
+      if (value instanceof realm.ArrayBuffer) {
+        clone = value.slice(0)
+        cache.set(value, clone)
+        return clone
+      }
+    }
+
+    // if the value cannot / should not be cloned, don't
+    if (
+      // promise-like
+      typeof value.then === 'function' ||
+      // errors
+      value instanceof Error ||
+      // weakmaps
+      (realm.WeakMap && value instanceof realm.WeakMap) ||
+      // weaksets
+      (realm.WeakSet && value instanceof realm.WeakSet)
+    ) {
+      return value
+    }
+
+    // assume anything left is a custom constructor
+    return getObjectClone(value, realm, handleCopy, cache)
+  }
+
+  return handleCopy(value, createCache())
+}
+
+/**
+ * @function strictCopy
+ *
+ * @description
+ * copy the value with `strict` option pre-applied
+ *
+ * @param value the value to copy
+ * @param [options] the options for copying with
+ * @param [options.realm] the realm (this) value the value is copied from
+ * @returns the copied value
+ */
+copy.strict = function strictCopy(value: any, options?: FastCopy.Options) {
+  return copy(value, {
+    isStrict: true,
+    realm: options ? options.realm : void 0,
+  })
+}
+
+export default copy
diff --git a/packages/pinia/src/devtools/plugin.ts b/packages/pinia/src/devtools/plugin.ts
index d62ac5f0d8..cabe6216fd 100644
--- a/packages/pinia/src/devtools/plugin.ts
+++ b/packages/pinia/src/devtools/plugin.ts
@@ -27,7 +27,8 @@ import {
   PINIA_ROOT_ID,
   PINIA_ROOT_LABEL,
 } from './formatting'
-import { isPinia, toastMessage } from './utils'
+import { isPinia, toastMessage, formatStateDifferences } from './utils'
+import copy from './fastCopy'
 
 // timeline can be paused when directly changing the state
 let isTimelineActive = true
@@ -328,6 +329,8 @@ function addStoreToDevtools(app: DevtoolsApp, store: StoreGeneric) {
       store.$onAction(({ after, onError, name, args }) => {
         const groupId = runningActionId++
 
+        const initialState = copy(store.$state)
+
         api.addTimelineEvent({
           layerId: MUTATIONS_LAYER_ID,
           event: {
@@ -337,6 +340,7 @@ function addStoreToDevtools(app: DevtoolsApp, store: StoreGeneric) {
             data: {
               store: formatDisplay(store.$id),
               action: formatDisplay(name),
+              initialState,
               args,
             },
             groupId,
@@ -345,6 +349,9 @@ function addStoreToDevtools(app: DevtoolsApp, store: StoreGeneric) {
 
         after((result) => {
           activeAction = undefined
+          const newState = store.$state
+          const differences = formatStateDifferences(initialState, newState)
+
           api.addTimelineEvent({
             layerId: MUTATIONS_LAYER_ID,
             event: {
@@ -355,6 +362,8 @@ function addStoreToDevtools(app: DevtoolsApp, store: StoreGeneric) {
                 store: formatDisplay(store.$id),
                 action: formatDisplay(name),
                 args,
+                newState,
+                differences,
                 result,
               },
               groupId,
diff --git a/packages/pinia/src/devtools/utils.ts b/packages/pinia/src/devtools/utils.ts
index 07718b668c..61de32f95d 100644
--- a/packages/pinia/src/devtools/utils.ts
+++ b/packages/pinia/src/devtools/utils.ts
@@ -1,4 +1,5 @@
 import { Pinia } from '../rootStore'
+import { StateTree } from '../types'
 
 /**
  * Shows a toast or console.log
@@ -26,3 +27,82 @@ export function toastMessage(
 export function isPinia(o: any): o is Pinia {
   return '_a' in o && 'install' in o
 }
+
+export const realTypeOf = (subject: any) => {
+  const type = typeof subject
+  if (type !== 'object') return type
+
+  if (subject === Math) {
+    return 'math'
+  } else if (subject === null) {
+    return 'null'
+  } else if (Array.isArray(subject)) {
+    return 'array'
+  } else if (Object.prototype.toString.call(subject) === '[object Date]') {
+    return 'date'
+  } else if (
+    typeof subject.toString === 'function' &&
+    /^\/.*\//.test(subject.toString())
+  ) {
+    return 'regexp'
+  }
+  return 'object'
+}
+
+export function formatStateDifferences(
+  initialState: StateTree,
+  newState: StateTree
+): StateTree {
+  const stateDifferences: StateTree = {}
+
+  for (const key in newState) {
+    const oldType = realTypeOf(initialState[key])
+    const newType = realTypeOf(newState[key])
+
+    if (oldType !== newType) {
+      stateDifferences[key] = newState[key]
+      continue
+    }
+
+    switch (newType) {
+      case 'object':
+        const oldHash = JSON.stringify(initialState[key])
+        const newHash = JSON.stringify(newState[key])
+
+        if (oldHash !== newHash) {
+          const diffsInObject = formatStateDifferences(
+            initialState[key],
+            newState[key]
+          )
+
+          if (Object.keys(diffsInObject).length) {
+            stateDifferences[key] = diffsInObject
+          }
+        }
+        break
+      case 'date':
+        if (initialState[key] - newState[key] !== 0) {
+          stateDifferences[key] = newState[key]
+        }
+        break
+      case 'array':
+      case 'regexp':
+        if (initialState[key].toString() !== newState[key].toString()) {
+          stateDifferences[key] = newState[key]
+        }
+        break
+      default:
+        if (initialState[key] !== newState[key]) {
+          stateDifferences[key] = newState[key]
+        }
+    }
+  }
+
+  Object.keys(initialState).forEach((key) => {
+    if (!(key in newState)) {
+      stateDifferences[key] = undefined
+    }
+  })
+
+  return stateDifferences
+}