diff --git a/contracts/GeyserRegistry.sol b/contracts/GeyserRegistry.sol
new file mode 100644
index 0000000..b99da86
--- /dev/null
+++ b/contracts/GeyserRegistry.sol
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-3.0-only
+pragma solidity ^0.8.24;
+
+import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";
+
+/// @title GeyserRegistry
+contract GeyserRegistry is Ownable {
+    mapping(address => bool) public geysers;
+
+    event InstanceAdded(address instance);
+    event InstanceRemoved(address instance);
+
+    constructor() Ownable(msg.sender) {}
+
+    function register(address instance) external onlyOwner {
+        require(!geysers[instance], "GeyserRegistry: Geyser already registered");
+        geysers[instance] = true;
+        emit InstanceAdded(instance);
+    }
+
+    function deregister(address instance) external onlyOwner {
+        require(geysers[instance], "GeyserRegistry: Geyser not registered");
+        delete geysers[instance];
+        emit InstanceRemoved(instance);
+    }
+}
diff --git a/test/registry.ts b/test/registry.ts
new file mode 100644
index 0000000..7a283e6
--- /dev/null
+++ b/test/registry.ts
@@ -0,0 +1,112 @@
+import { ethers } from "hardhat";
+import { expect } from "chai";
+import { Contract } from "ethers";
+
+// Generated by chat-gpt
+describe("GeyserRegistry Contract", () => {
+  let GeyserRegistry: Contract;
+  let deployer: any;
+  let nonOwner: any;
+  let geyserAddress: string;
+  let unregisteredAddress: string;
+
+  beforeEach(async () => {
+    [deployer, nonOwner] = await ethers.getSigners();
+    geyserAddress = ethers.Wallet.createRandom().address; // Mock address
+    unregisteredAddress = ethers.Wallet.createRandom().address; // Mock address
+
+    const GeyserRegistryFactory = await ethers.getContractFactory(
+      "GeyserRegistry",
+      deployer,
+    );
+    GeyserRegistry = await GeyserRegistryFactory.deploy();
+  });
+
+  describe("Deployment", () => {
+    it("should deploy with the correct owner", async () => {
+      const owner = await GeyserRegistry.owner();
+      expect(owner).to.equal(deployer.address);
+    });
+
+    it("should have no geysers initially", async () => {
+      const isGeyser = await GeyserRegistry.geysers(geyserAddress);
+      expect(isGeyser).to.equal(false);
+    });
+  });
+
+  describe("Registering a Geyser", () => {
+    it("should allow the owner to register a geyser", async () => {
+      const tx = await GeyserRegistry.register(geyserAddress);
+      await tx.wait();
+
+      const isGeyser = await GeyserRegistry.geysers(geyserAddress);
+      expect(isGeyser).to.equal(true);
+    });
+
+    it("should emit InstanceAdded when a geyser is registered", async () => {
+      await expect(GeyserRegistry.register(geyserAddress))
+        .to.emit(GeyserRegistry, "InstanceAdded")
+        .withArgs(geyserAddress);
+    });
+
+    it("should revert if a non-owner tries to register", async () => {
+      await expect(
+        GeyserRegistry.connect(nonOwner).register(geyserAddress),
+      ).to.be.revertedWithCustomError(GeyserRegistry, "OwnableUnauthorizedAccount");
+    });
+
+    it("should revert if the geyser is already registered", async () => {
+      await GeyserRegistry.register(geyserAddress);
+      await expect(GeyserRegistry.register(geyserAddress)).to.be.revertedWith(
+        "GeyserRegistry: Geyser already registered",
+      );
+    });
+  });
+
+  describe("Deregistering a Geyser", () => {
+    beforeEach(async function () {
+      await GeyserRegistry.register(geyserAddress);
+    });
+
+    it("should allow the owner to deregister a geyser", async () => {
+      const tx = await GeyserRegistry.deregister(geyserAddress);
+      await tx.wait();
+
+      const isGeyser = await GeyserRegistry.geysers(geyserAddress);
+      expect(isGeyser).to.equal(false);
+    });
+
+    it("should emit InstanceRemoved when a geyser is deregistered", async () => {
+      await expect(GeyserRegistry.deregister(geyserAddress))
+        .to.emit(GeyserRegistry, "InstanceRemoved")
+        .withArgs(geyserAddress);
+    });
+
+    it("should revert if a non-owner tries to deregister", async () => {
+      await expect(
+        GeyserRegistry.connect(nonOwner).deregister(geyserAddress),
+      ).to.be.revertedWithCustomError(GeyserRegistry, "OwnableUnauthorizedAccount");
+    });
+
+    it("should revert if the geyser is not registered", async () => {
+      await expect(GeyserRegistry.deregister(unregisteredAddress)).to.be.revertedWith(
+        "GeyserRegistry: Geyser not registered",
+      );
+    });
+  });
+
+  describe("Edge Cases", () => {
+    it("should not allow re-registering the same geyser address", async () => {
+      await GeyserRegistry.register(geyserAddress);
+      await expect(GeyserRegistry.register(geyserAddress)).to.be.revertedWith(
+        "GeyserRegistry: Geyser already registered",
+      );
+    });
+
+    it("should revert when deregistering an unregistered address", async () => {
+      await expect(GeyserRegistry.deregister(unregisteredAddress)).to.be.revertedWith(
+        "GeyserRegistry: Geyser not registered",
+      );
+    });
+  });
+});