diff --git a/src/utils/merkle_tree.ts b/src/utils/merkle_tree.ts
index 5ce69305..f5c156eb 100644
--- a/src/utils/merkle_tree.ts
+++ b/src/utils/merkle_tree.ts
@@ -1,6 +1,6 @@
 // Haskell implementation: https://github.com/input-output-hk/hydra-poc/blob/master/plutus-merkle-tree/src/Plutus/MerkleTree.hs
-import { concat, equals } from "https://deno.land/std@0.148.0/bytes/mod.ts";
-import { Sha256 } from "https://deno.land/std@0.153.0/hash/sha256.ts";
+// TODO: get rid of async sha256
+import { concat, equals } from "jsr:@std/bytes";
 import { toHex } from "./utils.ts";
 
 type MerkleNode = {
@@ -20,18 +20,24 @@ export class MerkleTree {
   root!: MerkleNode | null;
 
   /** Construct Merkle tree from data, which get hashed with sha256 */
-  constructor(data: Array<Uint8Array>) {
-    this.root = MerkleTree.buildRecursively(data.map((d) => sha256(d)));
+  static async new(data: Array<Uint8Array>): Promise<MerkleTree> {
+    const tree = new this();
+    tree.root = await MerkleTree.buildRecursively(
+      await Promise.all(data.map((d) => sha256(d))),
+    );
+    return tree;
   }
 
   /** Construct Merkle tree from sha256 hashes */
-  static fromHashes(hashes: Array<Hash>): MerkleTree {
-    return new this(hashes);
+  static async fromHashes(hashes: Array<Hash>): Promise<MerkleTree> {
+    const tree = new this();
+    tree.root = await MerkleTree.buildRecursively(hashes);
+    return tree;
   }
 
-  private static buildRecursively(
+  private static async buildRecursively(
     hashes: Array<Hash>,
-  ): MerkleNode | null {
+  ): Promise<MerkleNode | null> {
     if (hashes.length <= 0) return null;
     if (hashes.length === 1) {
       return {
@@ -43,11 +49,11 @@ export class MerkleTree {
 
     const cutoff = Math.floor(hashes.length / 2);
     const [left, right] = [hashes.slice(0, cutoff), hashes.slice(cutoff)];
-    const lnode = this.buildRecursively(left);
-    const rnode = this.buildRecursively(right);
+    const lnode = await this.buildRecursively(left);
+    const rnode = await this.buildRecursively(right);
     if (lnode === null || rnode === null) return null;
     return {
-      node: combineHash(lnode.node, rnode.node),
+      node: await combineHash(lnode.node, rnode.node),
       left: lnode,
       right: rnode,
     };
@@ -58,8 +64,8 @@ export class MerkleTree {
     return this.root.node;
   }
 
-  getProof(data: Uint8Array): MerkleTreeProof {
-    const hash = sha256(data);
+  async getProof(data: Uint8Array): Promise<MerkleTreeProof> {
+    const hash = await sha256(data);
     const proof: MerkleTreeProof = [];
     const searchRecursively = (tree: MerkleNode | null) => {
       if (tree && equals(tree.node, hash)) return true;
@@ -90,23 +96,23 @@ export class MerkleTree {
     return searchRecursively(this.root);
   }
 
-  static verify(
+  static async verify(
     data: Uint8Array,
     rootHash: Hash,
     proof: MerkleTreeProof,
-  ): boolean {
-    const hash = sha256(data);
-    const searchRecursively = (
+  ): Promise<boolean> {
+    const hash = await sha256(data);
+    const searchRecursively = async (
       rootHash2: Hash,
       proof: MerkleTreeProof,
-    ): boolean => {
+    ): Promise<boolean> => {
       if (proof.length <= 0) return equals(rootHash, rootHash2);
       const [h, t] = [proof[0], proof.slice(1)];
       if (h.left) {
-        return searchRecursively(combineHash(h.left, rootHash2), t);
+        return searchRecursively(await combineHash(h.left, rootHash2), t);
       }
       if (h.right) {
-        return searchRecursively(combineHash(rootHash2, h.right), t);
+        return searchRecursively(await combineHash(rootHash2, h.right), t);
       }
       return false;
     };
@@ -129,10 +135,10 @@ export class MerkleTree {
 
 export { concat, equals };
 
-export function sha256(data: Uint8Array): Hash {
-  return new Uint8Array(new Sha256().update(data).arrayBuffer());
+export async function sha256(data: Uint8Array): Promise<Hash> {
+  return new Uint8Array(await crypto.subtle.digest("SHA-256", data));
 }
 
-export function combineHash(hash1: Hash, hash2: Hash): Hash {
-  return sha256(concat(hash1, hash2));
+export function combineHash(hash1: Hash, hash2: Hash): Promise<Hash> {
+  return sha256(concat([hash1, hash2]));
 }
diff --git a/src/utils/utils.ts b/src/utils/utils.ts
index fa6f75ec..4050349f 100644
--- a/src/utils/utils.ts
+++ b/src/utils/utils.ts
@@ -1,8 +1,4 @@
-import {
-  decode,
-  decodeString,
-  encodeToString,
-} from "https://deno.land/std@0.100.0/encoding/hex.ts";
+import { decodeHex, encodeHex } from "jsr:@std/encoding/hex";
 import {
   Addresses,
   type Assets,
@@ -15,16 +11,16 @@ import {
 import { crc8 } from "../misc/crc8.ts";
 
 export function fromHex(hex: string): Uint8Array {
-  return decodeString(hex);
+  return decodeHex(hex);
 }
 
 export function toHex(bytes: Uint8Array): string {
-  return encodeToString(bytes);
+  return encodeHex(bytes);
 }
 
 /** Convert a Hex encoded string to a Utf-8 encoded string. */
 export function toText(hex: string): string {
-  return new TextDecoder().decode(decode(new TextEncoder().encode(hex)));
+  return new TextDecoder().decode(fromHex(hex));
 }
 
 /** Convert a Utf-8 encoded string to a Hex encoded string. */
diff --git a/tests/mod.test.ts b/tests/mod.test.ts
index 80773cce..fda4c730 100644
--- a/tests/mod.test.ts
+++ b/tests/mod.test.ts
@@ -218,25 +218,25 @@ Deno.test("json datum to cbor datum", () => {
   assertEquals(cborDatum, Codec.encodeData(jsonDatum as DataJson));
 });
 
-Deno.test("Basic Merkle tree", () => {
+Deno.test("Basic Merkle tree", async () => {
   const data = [new Uint8Array([0]), new Uint8Array([1])];
-  const merkleTree = new MerkleTree(data);
+  const merkleTree = await MerkleTree.new(data);
   const rootHash = merkleTree.rootHash();
-  const proof = merkleTree.getProof(data[0]);
-  assert(MerkleTree.verify(data[0], rootHash, proof));
+  const proof = await merkleTree.getProof(data[0]);
+  assert(await MerkleTree.verify(data[0], rootHash, proof));
   assertEquals(merkleTree.size(), 3);
 });
 
-Deno.test("Merkle tree property test", () => {
-  fc.assert(
-    fc.property(
+Deno.test("Merkle tree property test", async () => {
+  await fc.assert(
+    fc.asyncProperty(
       fc.array(fc.uint8Array(), { minLength: 1 }),
-      (data: Uint8Array[]) => {
-        const merkleTree = new MerkleTree(data);
+      async (data: Uint8Array[]) => {
+        const merkleTree = await MerkleTree.new(data);
         const rootHash = merkleTree.rootHash();
         const index = Math.floor(Math.random() * data.length);
-        const proof = merkleTree.getProof(data[index]);
-        assert(MerkleTree.verify(data[index], rootHash, proof));
+        const proof = await merkleTree.getProof(data[index]);
+        assert(await MerkleTree.verify(data[index], rootHash, proof));
         assertEquals(
           merkleTree.size(),
           Math.max(0, data.length + (data.length - 1)),