diff --git a/build/esbuild-build.ts b/build/esbuild-build.ts
index 30d024c6..23d8bb48 100644
--- a/build/esbuild-build.ts
+++ b/build/esbuild-build.ts
@@ -33,7 +33,7 @@ export const esBuildContext: esbuild.BuildOptions = {
     ".svg": "dataurl",
   },
   outdir: "static/out",
-  define: createEnvDefines(["SUPABASE_URL", "SUPABASE_ANON_KEY"], { allNetworkUrls }),
+  define: createEnvDefines(["SUPABASE_URL", "SUPABASE_ANON_KEY"], { extraRpcs: allNetworkUrls }),
 };
 
 esbuild
@@ -62,6 +62,5 @@ function createEnvDefines(envVarNames: string[], extras: Record<string, unknown>
       defines[key] = JSON.stringify(extras[key]);
     }
   }
-  defines["extraRpcs"] = JSON.stringify(extraRpcs);
   return defines;
 }
diff --git a/static/scripts/rewards/helpers.ts b/static/scripts/rewards/helpers.ts
index a75d2fb8..c4cd343a 100644
--- a/static/scripts/rewards/helpers.ts
+++ b/static/scripts/rewards/helpers.ts
@@ -2,7 +2,7 @@ import axios from "axios";
 import { Contract, ethers } from "ethers";
 import { erc20Abi } from "./abis";
 import { JsonRpcProvider } from "@ethersproject/providers";
-import { networkRpcs } from "./constants";
+import { networkRpcs, networkExplorers } from "./constants";
 
 type DataType = {
   jsonrpc: string;
@@ -71,3 +71,20 @@ export async function getOptimalProvider(networkId: number) {
     ensAddress: "",
   });
 }
+
+export function getExplorerLinkForTx(networkId: number, hash: string): string {
+  if (!hash) return "#";
+  return `${networkExplorers[networkId]}/tx/${hash}`;
+}
+
+export function shortenTxHash(hash: string | undefined, length = 10): string {
+  if (!hash) return "";
+
+  const prefixLength = Math.floor(length / 2);
+  const suffixLength = length - prefixLength;
+
+  const prefix = hash.slice(0, prefixLength);
+  const suffix = hash.slice(-suffixLength);
+
+  return prefix + "..." + suffix;
+}
diff --git a/static/scripts/rewards/web3/erc20-permit.ts b/static/scripts/rewards/web3/erc20-permit.ts
index 014f68fb..ee704d91 100644
--- a/static/scripts/rewards/web3/erc20-permit.ts
+++ b/static/scripts/rewards/web3/erc20-permit.ts
@@ -1,7 +1,7 @@
 import { BigNumber, BigNumberish, ethers } from "ethers";
 import { permit2Abi } from "../abis";
 import { permit2Address } from "../constants";
-import { getErc20Contract, getOptimalProvider } from "../helpers";
+import { getErc20Contract, getOptimalProvider, getExplorerLinkForTx, shortenTxHash } from "../helpers";
 import { Erc20Permit } from "../render-transaction/tx-type";
 import { toaster, resetClaimButton, errorToast, loadingClaimButton, claimButton } from "../toaster";
 import { renderTransaction } from "../render-transaction/render-transaction";
@@ -9,6 +9,12 @@ import { connectWallet } from "./wallet";
 import invalidateButton from "../invalidate-component";
 import { JsonRpcProvider } from "@ethersproject/providers";
 import { tokens } from "../render-transaction/render-token-symbol";
+import { createClient } from "@supabase/supabase-js";
+
+declare const SUPABASE_URL: string;
+declare const SUPABASE_ANON_KEY: string;
+
+const supabase = createClient(SUPABASE_URL, SUPABASE_ANON_KEY);
 
 export async function fetchTreasury(
   permit: Erc20Permit,
@@ -59,7 +65,8 @@ export function claimErc20PermitHandler(permit: Erc20Permit, provider: JsonRpcPr
       toaster.create("info", `Transaction sent`);
       const receipt = await tx.wait();
       toaster.create("success", `Claim Complete.`);
-      console.log(receipt.transactionHash); // @TODO: post to database
+
+      await updatePermitTxHash(permit, receipt.transactionHash);
 
       claimButton.element.removeEventListener("click", handler);
       renderTransaction(provider).catch(console.error);
@@ -74,6 +81,13 @@ export function claimErc20PermitHandler(permit: Erc20Permit, provider: JsonRpcPr
 }
 
 export async function checkPermitClaimable(permit: Erc20Permit, signer: ethers.providers.JsonRpcSigner | null, provider: JsonRpcProvider) {
+  const permitHash = await doesPermitHaveTxHash(permit);
+  if (permitHash !== null) {
+    const explorerLink = `<a href="${getExplorerLinkForTx(permit.networkId, permitHash)}" target=_blank >${shortenTxHash(permitHash)}</a>`;
+    toaster.create("error", `This reward has already been claimed. Transaction hash: ${explorerLink}`);
+    return false;
+  }
+
   const isClaimed = await isNonceClaimed(permit);
   if (isClaimed) {
     toaster.create("error", `Your reward for this task has already been claimed or invalidated.`);
@@ -182,3 +196,37 @@ export function nonceBitmap(nonce: BigNumberish): { wordPos: BigNumber; bitPos:
   const bitPos = BigNumber.from(nonce).and(255).toNumber();
   return { wordPos, bitPos };
 }
+
+export async function doesPermitHaveTxHash(permit: Erc20Permit): Promise<string | null> {
+  const { data, error } = await supabase
+    .from("permits")
+    .select("transaction")
+    // using only nonce in the condition as it's defined unique on db
+    .eq("nonce", permit.permit.nonce.toString());
+
+  if (data?.length == 1 && data[0].transaction !== null) {
+    return data[0].transaction;
+  }
+
+  if (error !== null) {
+    console.error(error);
+    throw error;
+  }
+
+  return null;
+}
+
+export async function updatePermitTxHash(permit: Erc20Permit, hash: string): Promise<void> {
+  const { error } = await supabase
+    .from("permits")
+    .update({ transaction: hash })
+    // using only nonce in the condition as it's defined unique on db
+    .eq("nonce", permit.permit.nonce.toString());
+
+  if (error !== null) {
+    console.error(error);
+    throw error;
+  } else {
+    return;
+  }
+}