diff --git a/packages/chopsticks/src/plugins/decode-key/index.ts b/packages/chopsticks/src/plugins/decode-key/index.ts
index bf399cbf..975eb884 100644
--- a/packages/chopsticks/src/plugins/decode-key/index.ts
+++ b/packages/chopsticks/src/plugins/decode-key/index.ts
@@ -1,6 +1,6 @@
 import { Config } from '../../schema'
 import { HexString } from '@polkadot/util/types'
-import { decodeKey } from '../../utils/decoder'
+import { decodeKey } from '@acala-network/chopsticks-core'
 import { defaultOptions } from '../../cli-options'
 import { setupContext } from '../../context'
 import type yargs from 'yargs'
diff --git a/packages/chopsticks/src/plugins/dry-run/rpc.ts b/packages/chopsticks/src/plugins/dry-run/rpc.ts
index 6495bcc7..27900394 100644
--- a/packages/chopsticks/src/plugins/dry-run/rpc.ts
+++ b/packages/chopsticks/src/plugins/dry-run/rpc.ts
@@ -78,10 +78,10 @@ export const rpc: Handler = async (context, [params]) => {
   if (raw) {
     return storageDiff
   }
-  const [oldData, newData, delta] = await decodeStorageDiff(context.chain.head, storageDiff)
+  const { oldState, newState, delta } = await decodeStorageDiff(context.chain.head, storageDiff)
   return {
-    old: oldData,
-    new: newData,
+    old: oldState,
+    new: newState,
     delta,
   }
 }
diff --git a/packages/chopsticks/src/utils/decoder.ts b/packages/chopsticks/src/utils/decoder.ts
index c71a5fec..c0789968 100644
--- a/packages/chopsticks/src/utils/decoder.ts
+++ b/packages/chopsticks/src/utils/decoder.ts
@@ -1,12 +1,6 @@
-import '@polkadot/types-codec'
-import { Block } from '@acala-network/chopsticks-core'
-import { DecoratedMeta } from '@polkadot/types/metadata/decorate/types'
+import { Block, decodeBlockStorageDiff } from '@acala-network/chopsticks-core'
 import { HexString } from '@polkadot/util/types'
-import { StorageEntry } from '@polkadot/types/primitive/types'
-import { StorageKey } from '@polkadot/types'
-import { blake2AsHex } from '@polkadot/util-crypto'
 import { create } from 'jsondiffpatch'
-import { hexToU8a, u8aToHex } from '@polkadot/util'
 import _ from 'lodash'
 
 const diffPatcher = create({
@@ -14,102 +8,11 @@ const diffPatcher = create({
   textDiff: { minLength: Number.MAX_VALUE }, // skip text diff
 })
 
-const _CACHE: Record<string, Record<HexString, StorageEntry>> = {}
-
-const getCache = (uid: string): Record<HexString, StorageEntry> => {
-  if (!_CACHE[uid]) {
-    _CACHE[uid] = {}
-  }
-  return _CACHE[uid]
-}
-
-const getStorageEntry = (meta: DecoratedMeta, block: Block, key: HexString) => {
-  const cache = getCache(block.chain.uid)
-  for (const [prefix, storageEntry] of Object.entries(cache)) {
-    if (key.startsWith(prefix)) return storageEntry
-  }
-  for (const module of Object.values(meta.query)) {
-    for (const storage of Object.values(module)) {
-      const keyPrefix = u8aToHex(storage.keyPrefix())
-      if (key.startsWith(keyPrefix)) {
-        cache[keyPrefix] = storage
-        return storage
-      }
-    }
-  }
-  return undefined
-}
-
-export const decodeKey = (
-  meta: DecoratedMeta,
-  block: Block,
-  key: HexString,
-): { storage?: StorageEntry; decodedKey?: StorageKey } => {
-  const storage = getStorageEntry(meta, block, key)
-  const decodedKey = meta.registry.createType('StorageKey', key)
-  if (storage) {
-    decodedKey.setMeta(storage.meta)
-    return { storage, decodedKey }
-  }
-  return {}
-}
-
-export const decodeKeyValue = (meta: DecoratedMeta, block: Block, key: HexString, value?: HexString | null) => {
-  const { storage, decodedKey } = decodeKey(meta, block, key)
-
-  if (!storage || !decodedKey) {
-    return { [key]: value }
-  }
-
-  const decodeValue = () => {
-    if (!value) return null
-    if (storage.section === 'substrate' && storage.method === 'code') {
-      return `:code blake2_256 ${blake2AsHex(value, 256)} (${hexToU8a(value).length} bytes)`
-    }
-    return meta.registry.createType(decodedKey.outputType, hexToU8a(value)).toHuman()
-  }
-
-  switch (decodedKey.args.length) {
-    case 2: {
-      return {
-        [storage.section]: {
-          [storage.method]: {
-            [decodedKey.args[0].toString()]: {
-              [decodedKey.args[1].toString()]: decodeValue(),
-            },
-          },
-        },
-      }
-    }
-    case 1: {
-      return {
-        [storage.section]: {
-          [storage.method]: {
-            [decodedKey.args[0].toString()]: decodeValue(),
-          },
-        },
-      }
-    }
-    default:
-      return {
-        [storage.section]: {
-          [storage.method]: decodeValue(),
-        },
-      }
-  }
-}
-
 export const decodeStorageDiff = async (block: Block, diff: [HexString, HexString | null][]) => {
-  const oldState = {}
-  const newState = {}
-  const meta = await block.meta
-  for (const [key, value] of diff) {
-    _.merge(oldState, decodeKeyValue(meta, block, key, (await block.get(key)) as any))
-    _.merge(newState, decodeKeyValue(meta, block, key, value))
-  }
+  const [oldState, newState] = await decodeBlockStorageDiff(block, diff)
   const oldStateWithoutEvents = _.cloneDeep(oldState)
   if (oldStateWithoutEvents['system']?.['events']) {
     oldStateWithoutEvents['system']['events'] = []
   }
-  return [oldState, newState, diffPatcher.diff(oldStateWithoutEvents, newState)]
+  return { oldState, newState, delta: diffPatcher.diff(oldStateWithoutEvents, newState) }
 }
diff --git a/packages/chopsticks/src/utils/generate-html-diff.ts b/packages/chopsticks/src/utils/generate-html-diff.ts
index 839032a7..9f08ede8 100644
--- a/packages/chopsticks/src/utils/generate-html-diff.ts
+++ b/packages/chopsticks/src/utils/generate-html-diff.ts
@@ -6,9 +6,9 @@ import { template } from 'lodash'
 import path from 'node:path'
 
 export const generateHtmlDiff = async (block: Block, diff: [HexString, HexString | null][]) => {
-  const [left, _right, delta] = await decodeStorageDiff(block, diff)
+  const { oldState, delta } = await decodeStorageDiff(block, diff)
   const htmlTemplate = readFileSync(path.join(__dirname, '../../template/diff.html'), 'utf-8')
-  return template(htmlTemplate)({ left: JSON.stringify(left), delta: JSON.stringify(delta) })
+  return template(htmlTemplate)({ left: JSON.stringify(oldState), delta: JSON.stringify(delta) })
 }
 
 export const generateHtmlDiffPreviewFile = async (
diff --git a/packages/core/src/utils/decoder.ts b/packages/core/src/utils/decoder.ts
new file mode 100644
index 00000000..7f73710c
--- /dev/null
+++ b/packages/core/src/utils/decoder.ts
@@ -0,0 +1,111 @@
+import '@polkadot/types-codec'
+import { Block } from '../blockchain/block'
+import { DecoratedMeta } from '@polkadot/types/metadata/decorate/types'
+import { HexString } from '@polkadot/util/types'
+import { StorageEntry } from '@polkadot/types/primitive/types'
+import { StorageKey } from '@polkadot/types'
+import { blake2AsHex } from '@polkadot/util-crypto'
+import { hexToU8a, u8aToHex } from '@polkadot/util'
+import _ from 'lodash'
+
+const _CACHE: Record<string, Map<HexString, StorageEntry>> = {}
+
+const getCache = (uid: string): Map<HexString, StorageEntry> => {
+  if (!_CACHE[uid]) {
+    _CACHE[uid] = new Map()
+  }
+  return _CACHE[uid]
+}
+
+const getStorageEntry = (meta: DecoratedMeta, block: Block, key: HexString) => {
+  const cache = getCache(block.chain.uid)
+  for (const [prefix, storageEntry] of cache.entries()) {
+    if (key.startsWith(prefix)) return storageEntry
+  }
+  for (const module of Object.values(meta.query)) {
+    for (const storage of Object.values(module)) {
+      const keyPrefix = u8aToHex(storage.keyPrefix())
+      if (key.startsWith(keyPrefix)) {
+        cache.set(keyPrefix, storage)
+        return storage
+      }
+    }
+  }
+  return undefined
+}
+
+export const decodeKey = (
+  meta: DecoratedMeta,
+  block: Block,
+  key: HexString,
+): { storage?: StorageEntry; decodedKey?: StorageKey } => {
+  const storage = getStorageEntry(meta, block, key)
+  const decodedKey = meta.registry.createType('StorageKey', key)
+  if (storage) {
+    decodedKey.setMeta(storage.meta)
+    return { storage, decodedKey }
+  }
+  return {}
+}
+
+export const decodeKeyValue = (meta: DecoratedMeta, block: Block, key: HexString, value?: HexString | null) => {
+  const { storage, decodedKey } = decodeKey(meta, block, key)
+
+  if (!storage || !decodedKey) {
+    return { [key]: value }
+  }
+
+  const decodeValue = () => {
+    if (!value) return null
+    if (storage.section === 'substrate' && storage.method === 'code') {
+      return `:code blake2_256 ${blake2AsHex(value, 256)} (${hexToU8a(value).length} bytes)`
+    }
+    return meta.registry.createType(decodedKey.outputType, hexToU8a(value)).toHuman()
+  }
+
+  switch (decodedKey.args.length) {
+    case 2: {
+      return {
+        [storage.section]: {
+          [storage.method]: {
+            [decodedKey.args[0].toString()]: {
+              [decodedKey.args[1].toString()]: decodeValue(),
+            },
+          },
+        },
+      }
+    }
+    case 1: {
+      return {
+        [storage.section]: {
+          [storage.method]: {
+            [decodedKey.args[0].toString()]: decodeValue(),
+          },
+        },
+      }
+    }
+    default:
+      return {
+        [storage.section]: {
+          [storage.method]: decodeValue(),
+        },
+      }
+  }
+}
+
+/**
+ * Decode block storage diff
+ * @param block Block to compare storage diff
+ * @param diff Storage diff
+ * @returns decoded old state and new state
+ */
+export const decodeBlockStorageDiff = async (block: Block, diff: [HexString, HexString | null][]) => {
+  const oldState = {}
+  const newState = {}
+  const meta = await block.meta
+  for (const [key, value] of diff) {
+    _.merge(oldState, decodeKeyValue(meta, block, key, (await block.get(key)) as any))
+    _.merge(newState, decodeKeyValue(meta, block, key, value))
+  }
+  return [oldState, newState]
+}
diff --git a/packages/core/src/utils/index.ts b/packages/core/src/utils/index.ts
index 67cdcfd6..574dc85a 100644
--- a/packages/core/src/utils/index.ts
+++ b/packages/core/src/utils/index.ts
@@ -6,6 +6,7 @@ import { Blockchain } from '../blockchain'
 
 export * from './set-storage'
 export * from './time-travel'
+export * from './decoder'
 
 export type GetKeys = (startKey?: string) => Promise<StorageKey<any>[]>
 
diff --git a/packages/e2e/src/decoder.test.ts b/packages/e2e/src/decoder.test.ts
index 16be82e5..e18d3c28 100644
--- a/packages/e2e/src/decoder.test.ts
+++ b/packages/e2e/src/decoder.test.ts
@@ -1,5 +1,5 @@
 import { afterAll, describe, expect, it } from 'vitest'
-import { decodeKey, decodeKeyValue } from '@acala-network/chopsticks/utils/decoder'
+import { decodeKey, decodeKeyValue } from '@acala-network/chopsticks-core/utils/decoder'
 
 import networks from './networks'