diff --git a/packages/contract.cm/src/onchain/contract.ts b/packages/contract.cm/src/onchain/contract.ts
index 1b5d48d..7cad51e 100644
--- a/packages/contract.cm/src/onchain/contract.ts
+++ b/packages/contract.cm/src/onchain/contract.ts
@@ -5,12 +5,18 @@ import { addMethodHandler, ContractHandlers, executeHandler, executor } from 'cw
 import { PUBLIC_METHODS } from '../offchain/shared';
 
 import { addWord } from './addWord';
+import { mutexLock } from './mutex/lock';
+import { mutexUnlock, mutexUnlockExec } from './mutex/unlock';
 
 const createModule = (): ContractHandlers => {
   const module: ContractHandlers = { handlers: {} };
 
   addMethodHandler(module, PUBLIC_METHODS.ADD_WORD, executor(addWord));
 
+  addMethodHandler(module, '_lock', mutexLock);
+  addMethodHandler(module, '_unlock', mutexUnlock);
+  addMethodHandler(module, '_unlock_exec', mutexUnlockExec);
+
   addMethodHandler(module, SELF_REGISTER_HANDLER_NAME, selfRegisterHandler);
 
   return module;
diff --git a/packages/contract.cm/src/onchain/mutex/access.ts b/packages/contract.cm/src/onchain/mutex/access.ts
new file mode 100644
index 0000000..c308620
--- /dev/null
+++ b/packages/contract.cm/src/onchain/mutex/access.ts
@@ -0,0 +1 @@
+export const mutexAccess = () => {};
diff --git a/packages/contract.cm/src/onchain/mutex/lock.ts b/packages/contract.cm/src/onchain/mutex/lock.ts
new file mode 100644
index 0000000..a4d2b64
--- /dev/null
+++ b/packages/contract.cm/src/onchain/mutex/lock.ts
@@ -0,0 +1,43 @@
+import {
+  constructClaim,
+  constructClaimKey,
+  constructContinueTx,
+  constructContractIssuer,
+  constructContractRef,
+  constructStore,
+  Context,
+  extractContractInfo,
+  getContractId,
+} from '@coinweb/contract-kit';
+
+export const mutexLock = (context: Context) => {
+  const { providedCweb } = extractContractInfo(context.tx);
+  const issuer = constructContractIssuer(getContractId(context.tx));
+
+  return [
+    constructContinueTx(
+      context,
+      [
+        constructStore(
+          constructClaim(constructClaimKey('mutex', context.call.txid.slice(0, 8)), { word: 'CLASH' }, '0x0')
+        ),
+      ],
+      [
+        {
+          callInfo: {
+            ref: constructContractRef(issuer, []),
+            methodInfo: {
+              methodName: '_unlock',
+              methodArgs: [],
+            },
+            contractInfo: {
+              providedCweb: providedCweb ? providedCweb - 1000n : 1000n,
+              authenticated: null,
+            },
+            contractArgs: [],
+          },
+        },
+      ]
+    ),
+  ];
+};
diff --git a/packages/contract.cm/src/onchain/mutex/unlock.ts b/packages/contract.cm/src/onchain/mutex/unlock.ts
new file mode 100644
index 0000000..2f3ccdb
--- /dev/null
+++ b/packages/contract.cm/src/onchain/mutex/unlock.ts
@@ -0,0 +1,59 @@
+import {
+  constructContinueTx,
+  constructContractIssuer,
+  constructContractRef,
+  constructRangeRead,
+  constructTake,
+  Context,
+  extractContractArgs,
+  extractContractInfo,
+  extractRead,
+  getContractId,
+} from '@coinweb/contract-kit';
+
+export const mutexUnlock = (context: Context) => {
+  const { providedCweb } = extractContractInfo(context.tx);
+  const issuer = constructContractIssuer(getContractId(context.tx));
+  return [
+    constructContinueTx(
+      context,
+      [],
+      [
+        {
+          callInfo: {
+            ref: constructContractRef(issuer, []),
+            methodInfo: {
+              methodName: '_unlock_exec',
+              methodArgs: [],
+            },
+            contractInfo: {
+              providedCweb: (providedCweb ? providedCweb - 1000n : 1000n) / 2n,
+              authenticated: null,
+            },
+            contractArgs: [constructRangeRead(issuer, 'mutex', {}, 10000)],
+          },
+        },
+        {
+          callInfo: {
+            ref: constructContractRef(issuer, []),
+            methodInfo: {
+              methodName: '_unlock',
+              methodArgs: [],
+            },
+            contractInfo: {
+              providedCweb: (providedCweb ? providedCweb - 1000n : 1000n) / 2n,
+              authenticated: null,
+            },
+            contractArgs: [],
+          },
+        },
+      ]
+    ),
+  ];
+};
+
+export const mutexUnlockExec = (context: Context) => {
+  const claim = extractContractArgs(context.tx)[0]!;
+  const take = extractRead(claim)![0];
+  return [constructContinueTx(context, [constructTake(take.content.key)])];
+};
diff --git a/packages/cwait/src/onchain/mutex/claims/access.ts b/packages/cwait/src/onchain/mutex/claims/access.ts
new file mode 100644
index 0000000..3c1c9ae
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/claims/access.ts
@@ -0,0 +1,26 @@
+import {
+  constructClaim,
+  constructClaimKey,
+  constructStore,
+  constructTake,
+  CwebStore,
+  GStore,
+} from '@coinweb/contract-kit';
+
+import { MutexAccessResult, MutexAccessStatus } from '../types';
+
+export const mutexAccessKey = 'mutex_access';
+
+export const constructMutexAccessFirstPart = () => [mutexAccessKey];
+
+export const constructMutexAccessClaimKey = (uniqueId: string) =>
+  constructClaimKey(constructMutexAccessFirstPart(), [uniqueId]);
+
+export const constructMutexAccessClaim = (uniqueId: string, status: MutexAccessStatus) =>
+  constructClaim(constructMutexAccessClaimKey(uniqueId), { status } satisfies MutexAccessResult, '0x0');
+
+export const constructMutexAccessClaimStore = (uniqueId: string, status: MutexAccessStatus): GStore<CwebStore> =>
+  constructStore(constructMutexAccessClaim(uniqueId, status));
+
+export const constructMutexAccessClaimTake = (uniqueId: string) =>
+  constructTake(constructMutexAccessClaimKey(uniqueId));
diff --git a/packages/cwait/src/onchain/mutex/claims/index.ts b/packages/cwait/src/onchain/mutex/claims/index.ts
new file mode 100644
index 0000000..ffb10d3
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/claims/index.ts
@@ -0,0 +1,2 @@
+export * from './access';
+export * from './lock';
diff --git a/packages/cwait/src/onchain/mutex/claims/lock.ts b/packages/cwait/src/onchain/mutex/claims/lock.ts
new file mode 100644
index 0000000..c307665
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/claims/lock.ts
@@ -0,0 +1,70 @@
+import {
+  constructClaim,
+  constructClaimKey,
+  constructContractIssuer,
+  constructRangeRead,
+  constructStore,
+  Context,
+  getContractId,
+  GRead,
+} from '@coinweb/contract-kit';
+import { CwebRead } from '@coinweb/contract-kit/dist/esm/operations/read';
+import { toHex } from 'lib/shared';
+
+import { rangeReadLimit } from '../settings';
+import { LockedKey, MutexLockState } from '../types';
+
+export const mutexLockKey = 'mutex_lock';
+
+export const constructMutexLockFirstPart = () => [mutexLockKey];
+
+export const constructMutexLockClaimKey = (lockId: string, timestamp: number) =>
+  constructClaimKey(constructMutexLockFirstPart(), [timestamp, lockId]);
+
+export const constructMutexLockClaim = ({
+  fee,
+  keys,
+  locked,
+  lockId,
+  timestamp,
+  processId,
+}: {
+  lockId: string;
+  timestamp: number;
+  locked: boolean;
+  keys: LockedKey[];
+  fee: bigint;
+  processId: string;
+}) =>
+  constructClaim(
+    constructMutexLockClaimKey(lockId, timestamp),
+    { locked, keys, processId } satisfies MutexLockState,
+    toHex(fee)
+  );
+
+export const constructMutexLockClaimStore = ({
+  fee,
+  keys,
+  locked,
+  lockId,
+  timestamp,
+  processId,
+}: {
+  fee: bigint;
+  keys: LockedKey[];
+  locked: boolean;
+  lockId: string;
+  timestamp: number;
+  processId: string;
+}) => constructStore(constructMutexLockClaim({ fee, keys, locked, lockId, timestamp, processId }));
+
+export const constructMutexLockClaimRangeRead = (context: Context): GRead<CwebRead> =>
+  constructRangeRead(
+    constructContractIssuer(getContractId(context.tx)),
+    constructMutexLockFirstPart(),
+    {},
+    rangeReadLimit
+  );
+
+// export const constructMutexLockClaimTake = (lockId: string, timestamp: number) =>
+//   constructTake(constructMutexLockClaimKey(lockId, timestamp));
diff --git a/packages/cwait/src/onchain/mutex/index.ts b/packages/cwait/src/onchain/mutex/index.ts
new file mode 100644
index 0000000..c5a0114
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/index.ts
@@ -0,0 +1,20 @@
+import {
+  execLockMethodName,
+  getAccessMethodName,
+  lockMethodName,
+  mutexExecLock,
+  mutexGetAccess,
+  mutexLock,
+  mutexUnlock,
+  unlockMethodName,
+} from './methods';
+
+export * from './claims';
+export * from './types';
+
+export const mutexMethods = {
+  [execLockMethodName]: mutexExecLock,
+  [getAccessMethodName]: mutexGetAccess,
+  [lockMethodName]: mutexLock,
+  [unlockMethodName]: mutexUnlock,
+};
diff --git a/packages/cwait/src/onchain/mutex/methods/execLock.ts b/packages/cwait/src/onchain/mutex/methods/execLock.ts
new file mode 100644
index 0000000..0284cf8
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/methods/execLock.ts
@@ -0,0 +1,75 @@
+import {
+  constructClaim,
+  constructContinueTx,
+  constructContractRef,
+  constructStore,
+  constructTake,
+  Context,
+  extractContractArgs,
+  extractRead,
+  passCwebFrom,
+} from '@coinweb/contract-kit';
+import { getCallParameters, getContractIssuer } from 'lib/onchain';
+import { toHex, TypedClaim } from 'lib/shared';
+
+import { lockFee } from '../settings';
+import { MutexLockState } from '../types';
+import { isMatchLockKeys } from '../utils';
+
+import { lockMethodName } from './names';
+
+export const mutexExecLock = (context: Context) => {
+  const { availableCweb } = getCallParameters(context);
+  const issuer = getContractIssuer(context);
+
+  const lockQueue = extractRead(extractContractArgs(context.tx)[0])?.map(
+    ({ content }) => content as TypedClaim<MutexLockState>
+  );
+
+  if (!lockQueue) {
+    throw new Error('No lock queue found');
+  }
+
+  const alreadyLockedKeys = lockQueue.filter(({ body }) => body.locked).map(({ key }) => key);
+
+  const lockCandidate = lockQueue.find(
+    ({ body, key }) => !body.locked && !alreadyLockedKeys.some((lockedKey) => isMatchLockKeys(lockedKey, key))
+  );
+
+  if (!lockCandidate) {
+    return [];
+  }
+
+  return [
+    constructContinueTx(
+      context,
+      [
+        passCwebFrom(issuer, availableCweb),
+        constructTake(lockCandidate.key),
+        constructStore(
+          constructClaim(
+            lockCandidate.key,
+            { ...lockCandidate.body, locked: true },
+            toHex(BigInt(lockCandidate.fees_stored) - lockFee)
+          )
+        ),
+      ],
+      [
+        {
+          callInfo: {
+            ref: constructContractRef(issuer, []),
+            methodInfo: {
+              methodName: lockMethodName,
+              methodArgs: [],
+            },
+            contractInfo: {
+              providedCweb: lockFee,
+              authenticated: null,
+            },
+            contractArgs: [],
+          },
+        },
+      ]
+    ),
+  ];
+};
diff --git a/packages/cwait/src/onchain/mutex/methods/getAccess.ts b/packages/cwait/src/onchain/mutex/methods/getAccess.ts
new file mode 100644
index 0000000..28d2bdd
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/methods/getAccess.ts
@@ -0,0 +1,32 @@
+import { constructContinueTx, Context, extractContractArgs, extractRead } from '@coinweb/contract-kit';
+import { getContractArguments } from 'lib/onchain';
+import { TypedClaim } from 'lib/shared';
+
+import { constructMutexAccessClaimStore } from '../claims';
+import { MutexAccessStatus, MutexGetAccessArgs, MutexLockState } from '../types';
+import { isMatchLockKeys } from '../utils';
+
+export const mutexGetAccess = (context: Context) => {
+  const [claimKey, processId, uniqueId] = getContractArguments<MutexGetAccessArgs>(context);
+
+  const lockQueue = extractRead(extractContractArgs(context.tx)[0])?.map(
+    ({ content }) => content as TypedClaim<MutexLockState>
+  );
+
+  if (!lockQueue) {
+    throw new Error('No lock queue found');
+  }
+
+  const isLockedByOtherProcess = lockQueue.some(
+    ({ body }) => body.locked && body.processId !== processId && body.keys.some((key) => isMatchLockKeys(key, claimKey))
+  );
+
+  return [
+    constructContinueTx(context, [
+      constructMutexAccessClaimStore(
+        uniqueId,
+        isLockedByOtherProcess ? MutexAccessStatus.DENIED : MutexAccessStatus.GRANTED
+      ),
+    ]),
+  ];
+};
diff --git a/packages/cwait/src/onchain/mutex/methods/index.ts b/packages/cwait/src/onchain/mutex/methods/index.ts
new file mode 100644
index 0000000..287d9f5
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/methods/index.ts
@@ -0,0 +1,5 @@
+export * from './execLock';
+export * from './getAccess';
+export * from './lock';
+export * from './names';
+export * from './unlock';
diff --git a/packages/cwait/src/onchain/mutex/methods/lock.ts b/packages/cwait/src/onchain/mutex/methods/lock.ts
new file mode 100644
index 0000000..0a31048
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/methods/lock.ts
@@ -0,0 +1,34 @@
+import { constructContinueTx, constructContractRef, Context } from '@coinweb/contract-kit';
+import { getCallParameters, getContractIssuer } from 'lib/onchain';
+
+import { constructMutexLockClaimRangeRead } from '../claims';
+
+import { execLockMethodName } from './names';
+
+export const mutexLock = (context: Context) => {
+  const { availableCweb } = getCallParameters(context);
+  const issuer = getContractIssuer(context);
+
+  return [
+    constructContinueTx(
+      context,
+      [],
+      [
+        {
+          callInfo: {
+            ref: constructContractRef(issuer, []),
+            methodInfo: {
+              methodName: execLockMethodName,
+              methodArgs: [],
+            },
+            contractInfo: {
+              providedCweb: availableCweb - 700n,
+              authenticated: null,
+            },
+            contractArgs: [constructMutexLockClaimRangeRead(context)],
+          },
+        },
+      ]
+    ),
+  ];
+};
diff --git a/packages/cwait/src/onchain/mutex/methods/names.ts b/packages/cwait/src/onchain/mutex/methods/names.ts
new file mode 100644
index 0000000..269ca95
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/methods/names.ts
@@ -0,0 +1,4 @@
+export const lockMethodName = '_mutex_lock';
+export const execLockMethodName = '_mutex_execLock';
+export const getAccessMethodName = '_mutex_get_access';
+export const unlockMethodName = '_mutex_unlock';
diff --git a/packages/cwait/src/onchain/mutex/methods/unlock.ts b/packages/cwait/src/onchain/mutex/methods/unlock.ts
new file mode 100644
index 0000000..ec5167c
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/methods/unlock.ts
@@ -0,0 +1,38 @@
+import { constructContinueTx, constructContractRef, constructTake, Context, passCwebFrom } from '@coinweb/contract-kit';
+import { getCallParameters, getContractArguments, getContractIssuer } from 'lib/onchain';
+
+import { constructMutexLockClaimKey } from '../claims';
+import { lockFee } from '../settings';
+import { MutexUnlockArgs } from '../types';
+
+import { lockMethodName } from './names';
+
+export const mutexUnlock = (context: Context) => {
+  const { availableCweb } = getCallParameters(context);
+  const issuer = getContractIssuer(context);
+
+  const [lockId, timestamp] = getContractArguments<MutexUnlockArgs>(context);
+
+  return [
+    constructContinueTx(
+      context,
+      [passCwebFrom(issuer, availableCweb), constructTake(constructMutexLockClaimKey(lockId, timestamp))],
+      [
+        {
+          callInfo: {
+            ref: constructContractRef(issuer, []),
+            methodInfo: {
+              methodName: lockMethodName,
+              methodArgs: [],
+            },
+            contractInfo: {
+              providedCweb: lockFee,
+              authenticated: null,
+            },
+            contractArgs: [],
+          },
+        },
+      ]
+    ),
+  ];
+};
diff --git a/packages/cwait/src/onchain/mutex/settings.ts b/packages/cwait/src/onchain/mutex/settings.ts
new file mode 100644
index 0000000..e277112
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/settings.ts
@@ -0,0 +1,4 @@
+export const lockFee = 5000n;
+export const unlockFee = 1000n + lockFee;
+
+export const rangeReadLimit = 10000;
diff --git a/packages/cwait/src/onchain/mutex/types.ts b/packages/cwait/src/onchain/mutex/types.ts
new file mode 100644
index 0000000..2aec5c9
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/types.ts
@@ -0,0 +1,22 @@
+import { ClaimKey } from '@coinweb/contract-kit';
+
+export type LockedKey = Omit<ClaimKey, 'second_part'> & Partial<Pick<ClaimKey, 'second_part'>>;
+
+export type MutexLockState = {
+  locked: boolean;
+  keys: LockedKey[];
+  processId: string;
+};
+
+export enum MutexAccessStatus {
+  GRANTED = 'granted',
+  DENIED = 'denied',
+}
+
+export type MutexAccessResult = {
+  status: MutexAccessStatus;
+};
+
+export type MutexGetAccessArgs = [claimKey: ClaimKey, processId: string, uniqueId: string];
+
+export type MutexUnlockArgs = [lockId: string, timestamp: number];
diff --git a/packages/cwait/src/onchain/mutex/utils/index.ts b/packages/cwait/src/onchain/mutex/utils/index.ts
new file mode 100644
index 0000000..f2fb770
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/utils/index.ts
@@ -0,0 +1 @@
+export * from './isMatchLockKeys';
diff --git a/packages/cwait/src/onchain/mutex/utils/isMatchLockKeys.ts b/packages/cwait/src/onchain/mutex/utils/isMatchLockKeys.ts
new file mode 100644
index 0000000..28d35dc
--- /dev/null
+++ b/packages/cwait/src/onchain/mutex/utils/isMatchLockKeys.ts
@@ -0,0 +1,9 @@
+import { LockedKey } from '../types';
+
+export const isMatchLockKeys = (lockKey1: LockedKey, lockKey2: LockedKey) => {
+  if (!lockKey1.second_part || !lockKey2.second_part) {
+    return lockKey1.first_part === lockKey2.first_part;
+  }
+
+  return lockKey1.first_part === lockKey2.first_part && lockKey1.second_part === lockKey2.second_part;
+};
diff --git a/packages/ui/.env b/packages/ui/.env
index 6a36b70..2964227 100644
--- a/packages/ui/.env
+++ b/packages/ui/.env
@@ -1,4 +1,4 @@
 VITE_API_URL='https://api-cloud.coinweb.io/wallet'
 VITE_EXPLORER_URL='https://explorer.coinweb.io'
 
-VITE_CONTRACT_ADDRESS="0x8c89cb42634cfe892290845d907af8ec2d482cead42afaef3ccc3cea4446fce5"
+VITE_CONTRACT_ADDRESS="0xbf9ca1687e3441bed1afd495405778a9c06c2f5173829d47d9b87dfb150063d8"