diff --git a/apps/web/src/App.tsx b/apps/web/src/App.tsx
index 8f54c0b..c049558 100644
--- a/apps/web/src/App.tsx
+++ b/apps/web/src/App.tsx
@@ -1,6 +1,6 @@
 import { useState } from "react";
 import type { RiskAssessment } from "@custos/core";
-import { requiresFriction, requiresHardBlock } from "@custos/core";
+import { parseDestinationAddress, requiresFriction, requiresHardBlock } from "@custos/core";
 import { analyzeSendIntent } from "./compositionRoot.js";
 
 export function App() {
@@ -8,17 +8,31 @@ export function App() {
   const [amount, setAmount] = useState("");
   const [context, setContext] = useState("");
   const [assessment, setAssessment] = useState<RiskAssessment | null>(null);
+  const [error, setError] = useState<string | null>(null);
   const [busy, setBusy] = useState(false);
 
   async function handleCheck() {
     setBusy(true);
+    setError(null);
+    setAssessment(null);
     try {
+      const parsed = parseDestinationAddress(address);
+      if (!parsed.ok) {
+        setError(
+          parsed.reason === "empty"
+            ? "Enter a destination address."
+            : "That is not a Tron (T...) or Ethereum (0x...) address.",
+        );
+        return;
+      }
       const result = await analyzeSendIntent.execute({
-        destination: { value: address, network: "tron" },
+        destination: parsed.address,
         amountUsdt: Number(amount) || 0,
         context: context ? { text: context } : undefined,
       });
       setAssessment(result);
+    } catch (err) {
+      setError(err instanceof Error ? err.message : "Analysis failed.");
     } finally {
       setBusy(false);
     }
@@ -33,11 +47,21 @@ export function App() {
         Destination address
         <input
           value={address}
-          onChange={(e) => setAddress(e.target.value)}
+          onChange={(e) => {
+            setAddress(e.target.value);
+            setError(null);
+          }}
           style={{ width: "100%", padding: 8 }}
           placeholder="TXyz... / 0x..."
+          aria-invalid={error !== null}
+          aria-describedby={error ? "address-error" : undefined}
         />
       </label>
+      {error && (
+        <p id="address-error" role="alert" style={{ color: "#c0392b", marginTop: 8 }}>
+          {error}
+        </p>
+      )}
 
       <label style={{ display: "block", marginTop: 12 }}>
         Amount (USDT)
@@ -72,6 +96,11 @@ export function App() {
           }}
         >
           <strong>Risk level: {assessment.level}</strong>
+          {assessment.addressReputation && (
+            <p>
+              Detected network: {assessment.addressReputation.address.network === "tron" ? "Tron" : "Ethereum"}
+            </p>
+          )}
           <p>{assessment.summary}</p>
           {requiresHardBlock(assessment.level) && <p>This send would be blocked — WDK signing must not proceed.</p>}
         </div>
diff --git a/packages/core/src/domain/services/__tests__/parseDestinationAddress.test.ts b/packages/core/src/domain/services/__tests__/parseDestinationAddress.test.ts
new file mode 100644
index 0000000..2b860cc
--- /dev/null
+++ b/packages/core/src/domain/services/__tests__/parseDestinationAddress.test.ts
@@ -0,0 +1,49 @@
+import { describe, expect, it } from "vitest";
+import { parseDestinationAddress } from "../parseDestinationAddress.js";
+
+describe("parseDestinationAddress", () => {
+  it("detects a Tron base58 address", () => {
+    const result = parseDestinationAddress("TLyqzVGLV1srkB7dToTAEqgDSfPtXRJZYH");
+
+    expect(result).toEqual({
+      ok: true,
+      address: { value: "TLyqzVGLV1srkB7dToTAEqgDSfPtXRJZYH", network: "tron" },
+    });
+  });
+
+  it("detects an Ethereum hex address regardless of checksum casing", () => {
+    const result = parseDestinationAddress("0x742d35Cc6634C0532925a3b8D4C9db96C4b4d8b6");
+
+    expect(result).toEqual({
+      ok: true,
+      address: { value: "0x742d35Cc6634C0532925a3b8D4C9db96C4b4d8b6", network: "ethereum" },
+    });
+  });
+
+  it("trims surrounding whitespace before matching", () => {
+    const result = parseDestinationAddress("  TLyqzVGLV1srkB7dToTAEqgDSfPtXRJZYH\n");
+
+    expect(result.ok).toBe(true);
+    if (result.ok) {
+      expect(result.address.value).toBe("TLyqzVGLV1srkB7dToTAEqgDSfPtXRJZYH");
+    }
+  });
+
+  it("rejects an empty or whitespace-only value", () => {
+    expect(parseDestinationAddress("")).toEqual({ ok: false, reason: "empty" });
+    expect(parseDestinationAddress("   ")).toEqual({ ok: false, reason: "empty" });
+  });
+
+  it("rejects formats that are neither Tron nor Ethereum instead of defaulting to tron", () => {
+    expect(parseDestinationAddress("bc1qar0srrr7xfkvy5l643lydnw9re59gtzzwf5mdq")).toEqual({
+      ok: false,
+      reason: "unrecognized",
+    });
+    expect(parseDestinationAddress("Tshort")).toEqual({ ok: false, reason: "unrecognized" });
+    expect(parseDestinationAddress("0xdead")).toEqual({ ok: false, reason: "unrecognized" });
+    expect(parseDestinationAddress("742d35Cc6634C0532925a3b8D4C9db96C4b4d8b6")).toEqual({
+      ok: false,
+      reason: "unrecognized",
+    });
+  });
+});
diff --git a/packages/core/src/domain/services/parseDestinationAddress.ts b/packages/core/src/domain/services/parseDestinationAddress.ts
new file mode 100644
index 0000000..30b6dfa
--- /dev/null
+++ b/packages/core/src/domain/services/parseDestinationAddress.ts
@@ -0,0 +1,31 @@
+import type { Address } from "../entities/Address.js";
+
+/** Tron base58check: 34 characters, T prefix, no 0/O/I/l. */
+const TRON_ADDRESS_RE = /^T[1-9A-HJ-NP-Za-km-z]{33}$/;
+
+/** Ethereum account: 0x plus 20 bytes hex. Checksum casing is not required. */
+const ETHEREUM_ADDRESS_RE = /^0x[0-9a-fA-F]{40}$/;
+
+export type ParseDestinationAddressResult =
+  | { readonly ok: true; readonly address: Address }
+  | { readonly ok: false; readonly reason: "empty" | "unrecognized" };
+
+/**
+ * Infers `ChainNetwork` from the address format so callers never have to
+ * hardcode `"tron"`. Addresses that match neither Tron nor Ethereum are
+ * rejected instead of being silently treated as Tron (risk-list keys are
+ * `network:value`, so a wrong network is a missed lookup).
+ */
+export function parseDestinationAddress(raw: string): ParseDestinationAddressResult {
+  const value = raw.trim();
+  if (value.length === 0) {
+    return { ok: false, reason: "empty" };
+  }
+  if (TRON_ADDRESS_RE.test(value)) {
+    return { ok: true, address: { value, network: "tron" } };
+  }
+  if (ETHEREUM_ADDRESS_RE.test(value)) {
+    return { ok: true, address: { value, network: "ethereum" } };
+  }
+  return { ok: false, reason: "unrecognized" };
+}
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index 626d9b0..5811ed0 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -13,6 +13,7 @@ export * from "./domain/ports/WalletPort.js";
 export * from "./domain/ports/RiskListPort.js";
 export * from "./domain/ports/AuditLogPort.js";
 export * from "./domain/services/detectAddressPoisoning.js";
+export * from "./domain/services/parseDestinationAddress.js";
 
 // Application
 export * from "./application/use-cases/AnalyzeSendIntent.js";