diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index adfa6f41c2..1278fb0379 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -66,8 +66,8 @@ jobs:
       - name: Run integration tests
         run: yarn test
 
-  test-storage:
-    name: Test storage layout
+  test-contracts:
+    name: Test storage layout and signatures
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
@@ -95,6 +95,9 @@ jobs:
       - name: Test Storage Layouts
         run: yarn run test:storage
 
+      - name: Test function signatures
+        run: yarn run test:signatures
+
   test-e2e:
     name: Test e2e
     runs-on: ubuntu-latest
diff --git a/.gitignore b/.gitignore
index 74466b7179..6b590d4029 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,6 +16,7 @@ forge-cache/
 #Storage layout test files
 test/storage/*-old.dot
 test/storage/*-old
+test/signatures/*-old
 
 # local deployment files
 network.json
diff --git a/package.json b/package.json
index 74526530ac..e80ec24486 100644
--- a/package.json
+++ b/package.json
@@ -20,6 +20,7 @@
     "test:unit": "forge test",
     "test:e2e:local-env": "yarn hardhat test test-e2e/*",
     "test:storage": "./scripts/storage_layout_test.bash",
+    "test:signatures": "./scripts/signatures_test.bash",
     "test:mutation": "ts-node test-mutation/gambitTester.ts",
     "deploy:local:token-bridge": "ts-node ./scripts/local-deployment/deployCreatorAndCreateTokenBridge.ts",
     "deploy:token-bridge-creator": "ts-node ./scripts/deployment/deployTokenBridgeCreator.ts",
diff --git a/scripts/signatures_test.bash b/scripts/signatures_test.bash
new file mode 100755
index 0000000000..f728e5d512
--- /dev/null
+++ b/scripts/signatures_test.bash
@@ -0,0 +1,17 @@
+#!/bin/bash
+output_dir="./test/signatures"
+for CONTRACTNAME in L1ERC20Gateway L1CustomGateway L1ReverseCustomGateway L1WethGateway L2ERC20Gateway L2CustomGateway L2ReverseCustomGateway L2WethGateway L1GatewayRouter L2GatewayRouter StandardArbERC20 L1AtomicTokenBridgeCreator L1TokenBridgeRetryableSender L2AtomicTokenBridgeFactory L1OrbitCustomGateway L1OrbitERC20Gateway L1OrbitGatewayRouter L1OrbitReverseCustomGateway
+do
+    echo "Checking for signature changes in $CONTRACTNAME"
+    [ -f "$output_dir/$CONTRACTNAME" ] && mv "$output_dir/$CONTRACTNAME" "$output_dir/$CONTRACTNAME-old"
+    forge inspect "$CONTRACTNAME" methods > "$output_dir/$CONTRACTNAME"
+    diff "$output_dir/$CONTRACTNAME-old" "$output_dir/$CONTRACTNAME"
+    if [[ $? != "0" ]]
+    then
+        CHANGED=1
+    fi
+done
+if [[ $CHANGED == 1 ]]
+then
+    exit 1
+fi
\ No newline at end of file
diff --git a/test/signatures/L1AtomicTokenBridgeCreator b/test/signatures/L1AtomicTokenBridgeCreator
new file mode 100644
index 0000000000..9d2ac7cc5e
--- /dev/null
+++ b/test/signatures/L1AtomicTokenBridgeCreator
@@ -0,0 +1,25 @@
+{
+  "canonicalL2FactoryAddress()": "bfd3e518",
+  "createTokenBridge(address,address,uint256,uint256)": "8277742b",
+  "gasLimitForL2FactoryDeployment()": "888139d4",
+  "getRouter(address)": "8369166d",
+  "inboxToL1Deployment(address)": "d9ce0ef9",
+  "inboxToL2Deployment(address)": "46052706",
+  "initialize(address)": "c4d66de8",
+  "l1Multicall()": "b1460a71",
+  "l1Templates()": "a5595da9",
+  "l1Weth()": "146bf4b1",
+  "l2CustomGatewayTemplate()": "41083186",
+  "l2MulticallTemplate()": "8c99e31c",
+  "l2RouterTemplate()": "381c9d99",
+  "l2StandardGatewayTemplate()": "d7eee6ca",
+  "l2TokenBridgeFactoryTemplate()": "1aeef2e2",
+  "l2WethGatewayTemplate()": "9095765e",
+  "l2WethTemplate()": "fd40ad85",
+  "owner()": "8da5cb5b",
+  "renounceOwnership()": "715018a6",
+  "retryableSender()": "36dddb97",
+  "setDeployment(address,(address,address,address,address,address),(address,address,address,address,address,address,address,address,address))": "4c149671",
+  "setTemplates((address,address,address,address,address,address,address,address),address,address,address,address,address,address,address,address,address,uint256)": "81fb9184",
+  "transferOwnership(address)": "f2fde38b"
+}
diff --git a/test/signatures/L1CustomGateway b/test/signatures/L1CustomGateway
new file mode 100644
index 0000000000..e756b93455
--- /dev/null
+++ b/test/signatures/L1CustomGateway
@@ -0,0 +1,24 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "encodeWithdrawal(uint256,address)": "020a6058",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "forceRegisterTokenToL2(address[],address[],uint256,uint256,uint256)": "1d3a689f",
+  "getExternalCall(uint256,address,bytes)": "f68a9082",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "inbox()": "fb0e722b",
+  "initialize(address,address,address,address)": "f8c8765e",
+  "l1ToL2Token(address)": "8a2dc014",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "outboundTransferCustomRefund(address,address,address,uint256,uint256,uint256,bytes)": "4fb1a07b",
+  "owner()": "8da5cb5b",
+  "postUpgradeInit()": "95fcea78",
+  "redirectedExits(bytes32)": "bcf2e6eb",
+  "registerTokenToL2(address,uint256,uint256,uint256)": "f26bdead",
+  "registerTokenToL2(address,uint256,uint256,uint256,address)": "ca346d4a",
+  "router()": "f887ea40",
+  "setOwner(address)": "13af4035",
+  "supportsInterface(bytes4)": "01ffc9a7",
+  "transferExitAndCall(uint256,address,address,bytes,bytes)": "bd5f3e7d",
+  "whitelist()": "93e59dc1"
+}
diff --git a/test/signatures/L1ERC20Gateway b/test/signatures/L1ERC20Gateway
new file mode 100644
index 0000000000..98c9bb6125
--- /dev/null
+++ b/test/signatures/L1ERC20Gateway
@@ -0,0 +1,20 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "cloneableProxyHash()": "97881f8d",
+  "counterpartGateway()": "2db09c1c",
+  "encodeWithdrawal(uint256,address)": "020a6058",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getExternalCall(uint256,address,bytes)": "f68a9082",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "inbox()": "fb0e722b",
+  "initialize(address,address,address,bytes32,address)": "a01893bf",
+  "l2BeaconProxyFactory()": "70fc045f",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "outboundTransferCustomRefund(address,address,address,uint256,uint256,uint256,bytes)": "4fb1a07b",
+  "postUpgradeInit()": "95fcea78",
+  "redirectedExits(bytes32)": "bcf2e6eb",
+  "router()": "f887ea40",
+  "supportsInterface(bytes4)": "01ffc9a7",
+  "transferExitAndCall(uint256,address,address,bytes,bytes)": "bd5f3e7d",
+  "whitelist()": "93e59dc1"
+}
diff --git a/test/signatures/L1GatewayRouter b/test/signatures/L1GatewayRouter
new file mode 100644
index 0000000000..428467cc21
--- /dev/null
+++ b/test/signatures/L1GatewayRouter
@@ -0,0 +1,24 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "defaultGateway()": "03295802",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getGateway(address)": "bda009fe",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "inbox()": "fb0e722b",
+  "initialize(address,address,address,address,address)": "1459457a",
+  "l1TokenToGateway(address)": "ed08fdc6",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "outboundTransferCustomRefund(address,address,address,uint256,uint256,uint256,bytes)": "4fb1a07b",
+  "owner()": "8da5cb5b",
+  "postUpgradeInit()": "95fcea78",
+  "router()": "f887ea40",
+  "setDefaultGateway(address,uint256,uint256,uint256)": "5625a952",
+  "setGateway(address,uint256,uint256,uint256)": "dd614569",
+  "setGateway(address,uint256,uint256,uint256,address)": "2d67b72d",
+  "setGateways(address[],address[],uint256,uint256,uint256)": "658b53f4",
+  "setOwner(address)": "13af4035",
+  "supportsInterface(bytes4)": "01ffc9a7",
+  "updateWhitelistSource(address)": "47466f98",
+  "whitelist()": "93e59dc1"
+}
diff --git a/test/signatures/L1OrbitCustomGateway b/test/signatures/L1OrbitCustomGateway
new file mode 100644
index 0000000000..678bff837f
--- /dev/null
+++ b/test/signatures/L1OrbitCustomGateway
@@ -0,0 +1,27 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "encodeWithdrawal(uint256,address)": "020a6058",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "forceRegisterTokenToL2(address[],address[],uint256,uint256,uint256)": "1d3a689f",
+  "forceRegisterTokenToL2(address[],address[],uint256,uint256,uint256,uint256)": "85f25597",
+  "getExternalCall(uint256,address,bytes)": "f68a9082",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "inbox()": "fb0e722b",
+  "initialize(address,address,address,address)": "f8c8765e",
+  "l1ToL2Token(address)": "8a2dc014",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "outboundTransferCustomRefund(address,address,address,uint256,uint256,uint256,bytes)": "4fb1a07b",
+  "owner()": "8da5cb5b",
+  "postUpgradeInit()": "95fcea78",
+  "redirectedExits(bytes32)": "bcf2e6eb",
+  "registerTokenToL2(address,uint256,uint256,uint256)": "f26bdead",
+  "registerTokenToL2(address,uint256,uint256,uint256,address)": "ca346d4a",
+  "registerTokenToL2(address,uint256,uint256,uint256,address,uint256)": "37daacad",
+  "registerTokenToL2(address,uint256,uint256,uint256,uint256)": "3e8ee3df",
+  "router()": "f887ea40",
+  "setOwner(address)": "13af4035",
+  "supportsInterface(bytes4)": "01ffc9a7",
+  "transferExitAndCall(uint256,address,address,bytes,bytes)": "bd5f3e7d",
+  "whitelist()": "93e59dc1"
+}
diff --git a/test/signatures/L1OrbitERC20Gateway b/test/signatures/L1OrbitERC20Gateway
new file mode 100644
index 0000000000..98c9bb6125
--- /dev/null
+++ b/test/signatures/L1OrbitERC20Gateway
@@ -0,0 +1,20 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "cloneableProxyHash()": "97881f8d",
+  "counterpartGateway()": "2db09c1c",
+  "encodeWithdrawal(uint256,address)": "020a6058",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getExternalCall(uint256,address,bytes)": "f68a9082",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "inbox()": "fb0e722b",
+  "initialize(address,address,address,bytes32,address)": "a01893bf",
+  "l2BeaconProxyFactory()": "70fc045f",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "outboundTransferCustomRefund(address,address,address,uint256,uint256,uint256,bytes)": "4fb1a07b",
+  "postUpgradeInit()": "95fcea78",
+  "redirectedExits(bytes32)": "bcf2e6eb",
+  "router()": "f887ea40",
+  "supportsInterface(bytes4)": "01ffc9a7",
+  "transferExitAndCall(uint256,address,address,bytes,bytes)": "bd5f3e7d",
+  "whitelist()": "93e59dc1"
+}
diff --git a/test/signatures/L1OrbitGatewayRouter b/test/signatures/L1OrbitGatewayRouter
new file mode 100644
index 0000000000..db159e0dd5
--- /dev/null
+++ b/test/signatures/L1OrbitGatewayRouter
@@ -0,0 +1,28 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "defaultGateway()": "03295802",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getGateway(address)": "bda009fe",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "inbox()": "fb0e722b",
+  "initialize(address,address,address,address,address)": "1459457a",
+  "l1TokenToGateway(address)": "ed08fdc6",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "outboundTransferCustomRefund(address,address,address,uint256,uint256,uint256,bytes)": "4fb1a07b",
+  "owner()": "8da5cb5b",
+  "postUpgradeInit()": "95fcea78",
+  "router()": "f887ea40",
+  "setDefaultGateway(address,uint256,uint256,uint256)": "5625a952",
+  "setDefaultGateway(address,uint256,uint256,uint256,uint256)": "c9a96997",
+  "setGateway(address,uint256,uint256,uint256)": "dd614569",
+  "setGateway(address,uint256,uint256,uint256,address)": "2d67b72d",
+  "setGateway(address,uint256,uint256,uint256,address,uint256)": "d7f7459c",
+  "setGateway(address,uint256,uint256,uint256,uint256)": "dc121927",
+  "setGateways(address[],address[],uint256,uint256,uint256)": "658b53f4",
+  "setGateways(address[],address[],uint256,uint256,uint256,uint256)": "55654af8",
+  "setOwner(address)": "13af4035",
+  "supportsInterface(bytes4)": "01ffc9a7",
+  "updateWhitelistSource(address)": "47466f98",
+  "whitelist()": "93e59dc1"
+}
diff --git a/test/signatures/L1OrbitReverseCustomGateway b/test/signatures/L1OrbitReverseCustomGateway
new file mode 100644
index 0000000000..678bff837f
--- /dev/null
+++ b/test/signatures/L1OrbitReverseCustomGateway
@@ -0,0 +1,27 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "encodeWithdrawal(uint256,address)": "020a6058",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "forceRegisterTokenToL2(address[],address[],uint256,uint256,uint256)": "1d3a689f",
+  "forceRegisterTokenToL2(address[],address[],uint256,uint256,uint256,uint256)": "85f25597",
+  "getExternalCall(uint256,address,bytes)": "f68a9082",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "inbox()": "fb0e722b",
+  "initialize(address,address,address,address)": "f8c8765e",
+  "l1ToL2Token(address)": "8a2dc014",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "outboundTransferCustomRefund(address,address,address,uint256,uint256,uint256,bytes)": "4fb1a07b",
+  "owner()": "8da5cb5b",
+  "postUpgradeInit()": "95fcea78",
+  "redirectedExits(bytes32)": "bcf2e6eb",
+  "registerTokenToL2(address,uint256,uint256,uint256)": "f26bdead",
+  "registerTokenToL2(address,uint256,uint256,uint256,address)": "ca346d4a",
+  "registerTokenToL2(address,uint256,uint256,uint256,address,uint256)": "37daacad",
+  "registerTokenToL2(address,uint256,uint256,uint256,uint256)": "3e8ee3df",
+  "router()": "f887ea40",
+  "setOwner(address)": "13af4035",
+  "supportsInterface(bytes4)": "01ffc9a7",
+  "transferExitAndCall(uint256,address,address,bytes,bytes)": "bd5f3e7d",
+  "whitelist()": "93e59dc1"
+}
diff --git a/test/signatures/L1ReverseCustomGateway b/test/signatures/L1ReverseCustomGateway
new file mode 100644
index 0000000000..e756b93455
--- /dev/null
+++ b/test/signatures/L1ReverseCustomGateway
@@ -0,0 +1,24 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "encodeWithdrawal(uint256,address)": "020a6058",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "forceRegisterTokenToL2(address[],address[],uint256,uint256,uint256)": "1d3a689f",
+  "getExternalCall(uint256,address,bytes)": "f68a9082",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "inbox()": "fb0e722b",
+  "initialize(address,address,address,address)": "f8c8765e",
+  "l1ToL2Token(address)": "8a2dc014",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "outboundTransferCustomRefund(address,address,address,uint256,uint256,uint256,bytes)": "4fb1a07b",
+  "owner()": "8da5cb5b",
+  "postUpgradeInit()": "95fcea78",
+  "redirectedExits(bytes32)": "bcf2e6eb",
+  "registerTokenToL2(address,uint256,uint256,uint256)": "f26bdead",
+  "registerTokenToL2(address,uint256,uint256,uint256,address)": "ca346d4a",
+  "router()": "f887ea40",
+  "setOwner(address)": "13af4035",
+  "supportsInterface(bytes4)": "01ffc9a7",
+  "transferExitAndCall(uint256,address,address,bytes,bytes)": "bd5f3e7d",
+  "whitelist()": "93e59dc1"
+}
diff --git a/test/signatures/L1TokenBridgeRetryableSender b/test/signatures/L1TokenBridgeRetryableSender
new file mode 100644
index 0000000000..15829bde49
--- /dev/null
+++ b/test/signatures/L1TokenBridgeRetryableSender
@@ -0,0 +1,7 @@
+{
+  "initialize()": "8129fc1c",
+  "owner()": "8da5cb5b",
+  "renounceOwnership()": "715018a6",
+  "sendRetryable((address,address,address,address,uint256,uint256),(address,address,address,address,address,address,address),(address,address,address,address,address),address,address,address,address,bool)": "d5402e89",
+  "transferOwnership(address)": "f2fde38b"
+}
diff --git a/test/signatures/L1WethGateway b/test/signatures/L1WethGateway
new file mode 100644
index 0000000000..c6b0853293
--- /dev/null
+++ b/test/signatures/L1WethGateway
@@ -0,0 +1,19 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "encodeWithdrawal(uint256,address)": "020a6058",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getExternalCall(uint256,address,bytes)": "f68a9082",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "inbox()": "fb0e722b",
+  "initialize(address,address,address,address,address)": "1459457a",
+  "l1Weth()": "146bf4b1",
+  "l2Weth()": "247b2768",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "outboundTransferCustomRefund(address,address,address,uint256,uint256,uint256,bytes)": "4fb1a07b",
+  "postUpgradeInit()": "95fcea78",
+  "redirectedExits(bytes32)": "bcf2e6eb",
+  "router()": "f887ea40",
+  "supportsInterface(bytes4)": "01ffc9a7",
+  "transferExitAndCall(uint256,address,address,bytes,bytes)": "bd5f3e7d"
+}
diff --git a/test/signatures/L2AtomicTokenBridgeFactory b/test/signatures/L2AtomicTokenBridgeFactory
new file mode 100644
index 0000000000..2aa137afc0
--- /dev/null
+++ b/test/signatures/L2AtomicTokenBridgeFactory
@@ -0,0 +1,3 @@
+{
+  "deployL2Contracts((bytes,bytes,bytes,bytes,bytes,bytes,bytes),address,address,address,address,address,address,address,address)": "b1c7a870"
+}
diff --git a/test/signatures/L2CustomGateway b/test/signatures/L2CustomGateway
new file mode 100644
index 0000000000..058d61b578
--- /dev/null
+++ b/test/signatures/L2CustomGateway
@@ -0,0 +1,14 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "exitNum()": "015234ab",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "initialize(address,address)": "485cc955",
+  "l1ToL2Token(address)": "8a2dc014",
+  "outboundTransfer(address,address,uint256,bytes)": "7b3a3c8b",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "postUpgradeInit()": "95fcea78",
+  "registerTokenFromL1(address[],address[])": "d4f5532f",
+  "router()": "f887ea40"
+}
diff --git a/test/signatures/L2ERC20Gateway b/test/signatures/L2ERC20Gateway
new file mode 100644
index 0000000000..a6128af74f
--- /dev/null
+++ b/test/signatures/L2ERC20Gateway
@@ -0,0 +1,15 @@
+{
+  "beaconProxyFactory()": "c05e6a95",
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "cloneableProxyHash()": "97881f8d",
+  "counterpartGateway()": "2db09c1c",
+  "exitNum()": "015234ab",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "getUserSalt(address)": "569f26ff",
+  "initialize(address,address,address)": "c0c53b8b",
+  "outboundTransfer(address,address,uint256,bytes)": "7b3a3c8b",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "postUpgradeInit()": "95fcea78",
+  "router()": "f887ea40"
+}
diff --git a/test/signatures/L2GatewayRouter b/test/signatures/L2GatewayRouter
new file mode 100644
index 0000000000..6a86a7a947
--- /dev/null
+++ b/test/signatures/L2GatewayRouter
@@ -0,0 +1,16 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "defaultGateway()": "03295802",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getGateway(address)": "bda009fe",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "initialize(address,address)": "485cc955",
+  "l1TokenToGateway(address)": "ed08fdc6",
+  "outboundTransfer(address,address,uint256,bytes)": "7b3a3c8b",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "postUpgradeInit()": "95fcea78",
+  "router()": "f887ea40",
+  "setDefaultGateway(address)": "f7c9362f",
+  "setGateway(address[],address[])": "4201f985"
+}
diff --git a/test/signatures/L2ReverseCustomGateway b/test/signatures/L2ReverseCustomGateway
new file mode 100644
index 0000000000..058d61b578
--- /dev/null
+++ b/test/signatures/L2ReverseCustomGateway
@@ -0,0 +1,14 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "exitNum()": "015234ab",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "initialize(address,address)": "485cc955",
+  "l1ToL2Token(address)": "8a2dc014",
+  "outboundTransfer(address,address,uint256,bytes)": "7b3a3c8b",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "postUpgradeInit()": "95fcea78",
+  "registerTokenFromL1(address[],address[])": "d4f5532f",
+  "router()": "f887ea40"
+}
diff --git a/test/signatures/L2WethGateway b/test/signatures/L2WethGateway
new file mode 100644
index 0000000000..860455a628
--- /dev/null
+++ b/test/signatures/L2WethGateway
@@ -0,0 +1,14 @@
+{
+  "calculateL2TokenAddress(address)": "a7e28d48",
+  "counterpartGateway()": "2db09c1c",
+  "exitNum()": "015234ab",
+  "finalizeInboundTransfer(address,address,address,uint256,bytes)": "2e567b36",
+  "getOutboundCalldata(address,address,address,uint256,bytes)": "a0c76a96",
+  "initialize(address,address,address,address)": "f8c8765e",
+  "l1Weth()": "146bf4b1",
+  "l2Weth()": "247b2768",
+  "outboundTransfer(address,address,uint256,bytes)": "7b3a3c8b",
+  "outboundTransfer(address,address,uint256,uint256,uint256,bytes)": "d2ce7d65",
+  "postUpgradeInit()": "95fcea78",
+  "router()": "f887ea40"
+}
diff --git a/test/signatures/StandardArbERC20 b/test/signatures/StandardArbERC20
new file mode 100644
index 0000000000..eb0e443c53
--- /dev/null
+++ b/test/signatures/StandardArbERC20
@@ -0,0 +1,23 @@
+{
+  "DOMAIN_SEPARATOR()": "3644e515",
+  "allowance(address,address)": "dd62ed3e",
+  "approve(address,uint256)": "095ea7b3",
+  "balanceOf(address)": "70a08231",
+  "bridgeBurn(address,uint256)": "74f4f547",
+  "bridgeInit(address,bytes)": "189db7d2",
+  "bridgeMint(address,uint256)": "8c2a993e",
+  "decimals()": "313ce567",
+  "decreaseAllowance(address,uint256)": "a457c2d7",
+  "increaseAllowance(address,uint256)": "39509351",
+  "isMaster()": "6f791d29",
+  "l1Address()": "c2eeeebd",
+  "l2Gateway()": "8fa74a0e",
+  "name()": "06fdde03",
+  "nonces(address)": "7ecebe00",
+  "permit(address,address,uint256,uint256,uint8,bytes32,bytes32)": "d505accf",
+  "symbol()": "95d89b41",
+  "totalSupply()": "18160ddd",
+  "transfer(address,uint256)": "a9059cbb",
+  "transferAndCall(address,uint256,bytes)": "4000aea0",
+  "transferFrom(address,address,uint256)": "23b872dd"
+}