diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 09880b1..f8a378b 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,6 +1,6 @@
 name: test
 
-on: workflow_dispatch
+on: push
 
 env:
   FOUNDRY_PROFILE: ci
@@ -29,6 +29,5 @@ jobs:
         id: build
 
       - name: Run Forge tests
-        run: |
-          forge test -vvv
+        run: forge test -vvvv --summary --detailed --gas-report
         id: test
diff --git a/README.md b/README.md
index c941148..599aeca 100644
--- a/README.md
+++ b/README.md
@@ -5,3 +5,11 @@ Tiny web3 protocols and applications.
 The aim is to keep it simple, quick to implement and interesting to learn Solidity.
 
 Inspired by [lil-web3](https://github.com/m1guelpf/lil-web3) by [Miguel Piedrafita](https://twitter.com/m1guelpf).
+
+## Table of contents
+
+- [Tiny ENS](#tiny-ens)
+
+## Tiny ENS
+
+Map human-readable names like 'vitalik.eth' to machine-readable identifiers such as Ethereum addresses like '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045' and support the reverse resolution.
diff --git a/foundry.toml b/foundry.toml
index 25b918f..92cd217 100644
--- a/foundry.toml
+++ b/foundry.toml
@@ -2,5 +2,8 @@
 src = "src"
 out = "out"
 libs = ["lib"]
+remappings = [
+  '@forge-std/=lib/forge-std/src/',
+]
 
 # See more config options https://github.com/foundry-rs/foundry/blob/master/crates/config/README.md#all-options
diff --git a/src/TinyENS.sol b/src/TinyENS.sol
new file mode 100644
index 0000000..d4cb583
--- /dev/null
+++ b/src/TinyENS.sol
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.13;
+
+/// @notice Interface for TinyENS.
+interface ITinyENS {
+  /// @notice Register a new ENS name and link it to an address.
+  /// @param name The ENS name to register.
+  function register(string memory name) external;
+
+  /// @notice Update the ENS name linked to an address.
+  /// @param newName The new ENS name.
+  function update(string memory newName) external;
+
+  /// @notice Resolve the address associated with a given ENS name.
+  /// @param name The ENS name to resolve.
+  /// @return The address associated with the ENS name.
+  function resolve(string memory name) external view returns (address);
+
+  /// @notice Reverse resolve an address to its associated ENS name.
+  /// @param targetAddress The target address to reverse resolve.
+  /// @return The ENS name associated with the address.
+  function reverse(address targetAddress) external view returns (string memory);
+}
+
+/// @title Tiny Ethereum Name Service
+/// @author leovct
+/// @notice Map human-readable names like 'vitalik.eth' to machine-readable identifiers such as
+/// Ethereum addresses like '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045' and support the reverse
+/// resolution.
+contract TinyENS is ITinyENS {
+  /// @notice Thrown when trying to register a name already registered.
+  error AlreadyRegistered();
+
+  /// @notice Map ENS names to addresses.
+  mapping(string => address) private registry;
+
+  /// @notice Map addresses to ENS names.
+  mapping(address => string) private reverseRegistry;
+
+  modifier notRegistered(string memory name) {
+    if (registry[name] != address(0)) revert AlreadyRegistered();
+    _;
+  }
+
+  function register(string memory name) public notRegistered(name) {
+    registry[name] = msg.sender;
+    reverseRegistry[msg.sender] = name;
+  }
+
+  function update(string memory newName) external notRegistered(newName) {
+    // Unlink the old name and the address.
+    string memory oldName = reverseRegistry[msg.sender];
+    registry[oldName] = address(0);
+    // Register the new name.
+    register(newName);
+  }
+
+  function resolve(string memory name) external view returns (address) {
+    return registry[name];
+  }
+
+  function reverse(address targetAddress) external view returns (string memory) {
+    return reverseRegistry[targetAddress];
+  }
+}
diff --git a/test/TinyENS.t.sol b/test/TinyENS.t.sol
new file mode 100644
index 0000000..5611622
--- /dev/null
+++ b/test/TinyENS.t.sol
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.13;
+
+import '../src/TinyENS.sol';
+import '@forge-std/Test.sol';
+
+contract TinyENSTest is Test {
+  TinyENS private tinyENS;
+
+  address private owner = makeAddr('owner');
+  address private alice = makeAddr('alice');
+  address private bob = makeAddr('bob');
+
+  function setUp() public {
+    vm.startPrank(owner);
+    tinyENS = new TinyENS();
+    console2.log('TinyENS deployed');
+    vm.stopPrank();
+  }
+
+  function testRegisterNewName() public {
+    vm.startPrank(alice);
+    tinyENS.register('alice.eth');
+    vm.stopPrank();
+
+    assertEq(tinyENS.resolve('alice.eth'), alice);
+    assertEq(tinyENS.reverse(alice), 'alice.eth');
+    console2.log('Alice registed alice.eth');
+  }
+
+  function testRegisterAlreadyRegisteredName() public {
+    vm.startPrank(alice);
+    tinyENS.register('alice.eth');
+    assertEq(tinyENS.resolve('alice.eth'), alice);
+    assertEq(tinyENS.reverse(alice), 'alice.eth');
+    console2.log('Alice registed alice.eth');
+
+    console2.log('Bob tries to register alice.eth');
+    vm.startPrank(bob);
+    vm.expectRevert(TinyENS.AlreadyRegistered.selector);
+    tinyENS.register('alice.eth');
+    assertEq(tinyENS.resolve('alice.eth'), alice);
+    assertEq(tinyENS.reverse(alice), 'alice.eth');
+    assertEq(tinyENS.reverse(bob), '');
+    vm.stopPrank();
+  }
+
+  function testUpdateWithNewName() public {
+    vm.startPrank(alice);
+    tinyENS.register('alice.eth');
+    assertEq(tinyENS.resolve('alice.eth'), alice);
+    assertEq(tinyENS.reverse(alice), 'alice.eth');
+    console2.log('Alice registed alice.eth');
+
+    tinyENS.register('alice22.eth');
+    assertEq(tinyENS.resolve('alice22.eth'), alice);
+    assertEq(tinyENS.reverse(alice), 'alice22.eth');
+    console2.log('Alice updated its name to alice22.eth');
+    vm.stopPrank();
+  }
+
+  function testUpdateWithAlreadyRegisteredName() public {
+    vm.startPrank(alice);
+    tinyENS.register('alice.eth');
+    console2.log('Alice registed alice.eth');
+
+    vm.startPrank(bob);
+    tinyENS.register('bob.eth');
+    console2.log('Bob registed bob.eth');
+
+    console2.log('Bob tries to update its name to alice.eth');
+    vm.expectRevert(TinyENS.AlreadyRegistered.selector);
+    tinyENS.update('alice.eth');
+    assertEq(tinyENS.resolve('alice.eth'), alice);
+    assertEq(tinyENS.reverse(alice), 'alice.eth');
+    assertEq(tinyENS.resolve('bob.eth'), bob);
+    assertEq(tinyENS.reverse(bob), 'bob.eth');
+    vm.stopPrank();
+  }
+}