diff --git a/web/account/siwe.react.js b/web/account/siwe.react.js
--- a/web/account/siwe.react.js
+++ b/web/account/siwe.react.js
@@ -9,6 +9,7 @@
   RainbowKitProvider,
   useConnectModal,
 } from '@rainbow-me/rainbowkit';
+import invariant from 'invariant';
 import _merge from 'lodash/fp/merge';
 import * as React from 'react';
 import { FaEthereum } from 'react-icons/fa';
@@ -16,6 +17,7 @@
   chain,
   configureChains,
   createClient,
+  useAccount,
   useSigner,
   WagmiConfig,
 } from 'wagmi';
@@ -25,17 +27,25 @@
 import {
   getSIWENonce,
   getSIWENonceActionTypes,
+  siweAuth,
+  siweAuthActionTypes,
 } from 'lib/actions/siwe-actions';
 import { createLoadingStatusSelector } from 'lib/selectors/loading-selectors';
+import type { LogInStartingPayload } from 'lib/types/account-types.js';
 import {
   useDispatchActionPromise,
   useServerCall,
 } from 'lib/utils/action-utils';
-import { siweMessageSigningExplanationStatements } from 'lib/utils/siwe-utils.js';
+import {
+  createSIWEMessage,
+  siweMessageSigningExplanationStatements,
+  siweStatementWithoutPublicKey,
+} from 'lib/utils/siwe-utils.js';
 
 import Button from '../components/button.react';
 import LoadingIndicator from '../loading-indicator.react';
 import { useSelector } from '../redux/redux-utils';
+import { webLogInExtraInfoSelector } from '../selectors/account-selectors.js';
 import css from './siwe.css';
 
 // details can be found https://0.6.x.wagmi.sh/docs/providers/configuring-chains
@@ -63,12 +73,15 @@
 );
 function SIWE(): React.Node {
   const { openConnectModal } = useConnectModal();
+  const { address } = useAccount();
   const { data: signer } = useSigner();
   const dispatchActionPromise = useDispatchActionPromise();
   const getSIWENonceCall = useServerCall(getSIWENonce);
   const getSIWENonceCallLoadingStatus = useSelector(
     getSIWENonceLoadingStatusSelector,
   );
+  const siweAuthCall = useServerCall(siweAuth);
+  const logInExtraInfo = useSelector(webLogInExtraInfoSelector);
 
   const [siweNonce, setSIWENonce] = React.useState<?string>(null);
 
@@ -91,6 +104,40 @@
     [],
   );
 
+  const callSIWEAuthEndpoint = React.useCallback(
+    (message: string, signature: string, extraInfo) =>
+      siweAuthCall({
+        message,
+        signature,
+        ...extraInfo,
+      }),
+    [siweAuthCall],
+  );
+
+  const attemptSIWEAuth = React.useCallback(
+    (message: string, signature: string) => {
+      const extraInfo = logInExtraInfo();
+      dispatchActionPromise(
+        siweAuthActionTypes,
+        callSIWEAuthEndpoint(message, signature, extraInfo),
+        undefined,
+        ({ calendarQuery: extraInfo.calendarQuery }: LogInStartingPayload),
+      );
+    },
+    [callSIWEAuthEndpoint, dispatchActionPromise, logInExtraInfo],
+  );
+
+  const onSignInButtonClick = React.useCallback(async () => {
+    invariant(siweNonce, 'nonce must be present during SIWE attempt');
+    const message = createSIWEMessage(
+      address,
+      siweStatementWithoutPublicKey,
+      siweNonce,
+    );
+    const signature = await signer.signMessage(message);
+    attemptSIWEAuth(message, signature);
+  }, [address, attemptSIWEAuth, signer, siweNonce]);
+
   let siweLoginForm;
   if (signer && !siweNonce) {
     siweLoginForm = (
@@ -109,7 +156,7 @@
         </div>
         <p>{siweMessageSigningExplanationStatements[0]}</p>
         <p>{siweMessageSigningExplanationStatements[1]}</p>
-        <Button variant="filled" type="submit" onClick={undefined}>
+        <Button variant="filled" onClick={onSignInButtonClick}>
           Sign in
         </Button>
       </div>