diff --git a/client/src/components/invite-modal.riot b/client/src/components/invite-modal.riot
index 89f5427..9f72e9d 100644
--- a/client/src/components/invite-modal.riot
+++ b/client/src/components/invite-modal.riot
@@ -10,7 +10,18 @@
         </button>
       </div>
 
-      <form if={!state.inviteUrl} onsubmit={handleSubmit}>
+      <div class="invite-tabs">
+        <button
+          class={'invite-tab' + (state.mode === 'email' ? ' active' : '')}
+          onclick={() => update({ mode: 'email', error: null, nostrResult: null })}
+        >Email</button>
+        <button
+          class={'invite-tab' + (state.mode === 'nostr' ? ' active' : '')}
+          onclick={() => update({ mode: 'nostr', error: null, inviteUrl: null })}
+        >Nostr</button>
+      </div>
+
+      <form if={state.mode === 'email' && !state.inviteUrl} onsubmit={handleSubmit}>
         <div class="form-group">
           <label for="invite-email">Email address</label>
           <input
@@ -33,7 +44,7 @@
         </div>
       </form>
 
-      <div if={state.inviteUrl} class="invite-success">
+      <div if={state.mode === 'email' && state.inviteUrl} class="invite-success">
         <p>Invite link generated!</p>
         <div class="invite-link-box">
           <code>{state.inviteUrl}</code>
@@ -44,6 +55,39 @@
           <button class="btn btn-primary" onclick={props.cbClose}>Done</button>
         </div>
       </div>
+
+      <form if={state.mode === 'nostr' && !state.nostrResult} onsubmit={handleNostrInvite}>
+        <div class="form-group">
+          <label for="invite-npub">Nostr public key</label>
+          <input
+            type="text"
+            id="invite-npub"
+            placeholder="npub1... or hex pubkey"
+            value={state.nostrPubkey}
+            oninput={e => update({ nostrPubkey: e.target.value })}
+            required
+          />
+        </div>
+
+        <p if={state.error} class="error-text">{state.error}</p>
+
+        <div class="modal-actions">
+          <button type="button" class="btn btn-ghost" onclick={props.cbClose}>Cancel</button>
+          <button type="submit" class="btn btn-primary" disabled={state.nostrLoading}>
+            {state.nostrLoading ? 'Adding...' : 'Add to Room'}
+          </button>
+        </div>
+      </form>
+
+      <div if={state.mode === 'nostr' && state.nostrResult} class="invite-success">
+        <p if={state.nostrResult === 'added'} class="success-msg">Added {state.nostrDisplayName} to room</p>
+        <p if={state.nostrResult === 'not_found'} class="info-msg">
+          This Nostr user hasn't joined GroupChat yet. They'll need to log in with their Nostr extension first.
+        </p>
+        <div class="modal-actions">
+          <button class="btn btn-primary" onclick={props.cbClose}>Done</button>
+        </div>
+      </div>
     </div>
   </div>
 
@@ -150,6 +194,49 @@
       font-size: var(--text-xs);
       color: var(--text-muted);
     }
+
+    .invite-tabs {
+      display: flex;
+      gap: var(--space-xs);
+      margin-bottom: var(--space-lg);
+      border-bottom: 1px solid var(--border);
+      padding-bottom: var(--space-xs);
+    }
+
+    .invite-tab {
+      background: none;
+      border: none;
+      padding: var(--space-xs) var(--space-md);
+      font-size: var(--text-sm);
+      color: var(--text-secondary);
+      cursor: pointer;
+      border-radius: var(--radius-md) var(--radius-md) 0 0;
+      transition: color var(--transition-fast), background var(--transition-fast);
+    }
+
+    .invite-tab:hover {
+      color: var(--text-primary);
+      background: var(--bg-tertiary);
+    }
+
+    .invite-tab.active {
+      color: var(--accent);
+      border-bottom: 2px solid var(--accent);
+      font-weight: 500;
+    }
+
+    .success-msg {
+      color: var(--success);
+      font-weight: 500;
+      margin-bottom: var(--space-md);
+    }
+
+    .info-msg {
+      color: var(--text-secondary);
+      font-size: var(--text-sm);
+      line-height: 1.5;
+      margin-bottom: var(--space-md);
+    }
   </style>
 
   <script>
@@ -157,10 +244,15 @@
 
     export default {
       state: {
+        mode: 'email',
         email: '',
+        nostrPubkey: '',
         error: null,
         loading: false,
+        nostrLoading: false,
         inviteUrl: null,
+        nostrResult: null,
+        nostrDisplayName: '',
       },
 
       handleOverlayClick() {
@@ -185,6 +277,25 @@
         }
       },
 
+      async handleNostrInvite(e) {
+        e.preventDefault()
+        this.update({ nostrLoading: true, error: null })
+
+        try {
+          const result = await api.inviteByNostr({
+            room_id: this.props.roomId,
+            nostr_pubkey: this.state.nostrPubkey.trim(),
+          })
+          this.update({
+            nostrResult: result.status,
+            nostrDisplayName: result.display_name || '',
+            nostrLoading: false,
+          })
+        } catch (err) {
+          this.update({ error: err.message, nostrLoading: false })
+        }
+      },
+
       copyLink() {
         navigator.clipboard.writeText(this.state.inviteUrl)
       },
diff --git a/client/src/components/login-page.riot b/client/src/components/login-page.riot
index 2df54fd..4ac53f0 100644
--- a/client/src/components/login-page.riot
+++ b/client/src/components/login-page.riot
@@ -38,6 +38,17 @@
         </button>
       </form>
 
+      <div if={state.hasNostr} class="nostr-divider">
+        <span>or</span>
+      </div>
+
+      <button if={state.hasNostr} class="btn btn-nostr btn-full" onclick={handleNostrLogin} disabled={state.nostrLoading}>
+        <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" style="margin-right: 8px; vertical-align: -2px;">
+          <path d="M21 2l-2 2m-7.61 7.61a5.5 5.5 0 1 1-7.778 7.778 5.5 5.5 0 0 1 7.777-7.777zm0 0L15.5 7.5m0 0l3 3L22 7l-3-3m-3.5 3.5L19 4"/>
+        </svg>
+        {state.nostrLoading ? 'Connecting...' : 'Login with Nostr'}
+      </button>
+
       <p class="auth-footer">
         Don't have an account?
         <a href="#" onclick={e => { e.preventDefault(); props.cbSwitch() }}>Register</a>
@@ -104,6 +115,47 @@
       margin-bottom: var(--space-sm);
     }
 
+    .nostr-divider {
+      display: flex;
+      align-items: center;
+      gap: var(--space-md);
+      margin: var(--space-lg) 0;
+      color: var(--text-muted);
+      font-size: var(--text-sm);
+    }
+
+    .nostr-divider::before,
+    .nostr-divider::after {
+      content: '';
+      flex: 1;
+      height: 1px;
+      background: var(--border);
+    }
+
+    .btn-nostr {
+      background: #8B5CF6;
+      color: white;
+      border: none;
+      padding: var(--space-sm) var(--space-md);
+      border-radius: var(--radius-md);
+      font-size: var(--text-sm);
+      font-weight: 500;
+      cursor: pointer;
+      transition: background var(--transition-fast);
+      display: flex;
+      align-items: center;
+      justify-content: center;
+    }
+
+    .btn-nostr:hover:not(:disabled) {
+      background: #7C3AED;
+    }
+
+    .btn-nostr:disabled {
+      opacity: 0.6;
+      cursor: not-allowed;
+    }
+
     .auth-footer {
       text-align: center;
       margin-top: var(--space-lg);
@@ -114,6 +166,7 @@
 
   <script>
     import { api } from '../services/api.js'
+    import { hasNostrExtension, getPublicKey, signEvent, fetchNostrProfile } from '../services/nostr.js'
 
     export default {
       state: {
@@ -121,6 +174,15 @@
         password: '',
         error: null,
         loading: false,
+        hasNostr: false,
+        nostrLoading: false,
+      },
+
+      onMounted() {
+        // Detect after a tick — extensions inject window.nostr asynchronously
+        setTimeout(() => {
+          this.update({ hasNostr: hasNostrExtension() })
+        }, 100)
       },
 
       async handleSubmit(e) {
@@ -137,6 +199,47 @@
           this.update({ error: err.message, loading: false })
         }
       },
+
+      async handleNostrLogin() {
+        this.update({ nostrLoading: true, error: null })
+
+        try {
+          // 1. Get challenge
+          const { challenge } = await api.nostrChallenge()
+
+          // Decode JWT payload to get nonce (middle segment)
+          const nonce = JSON.parse(atob(challenge.split('.')[1])).nonce
+
+          // 2. Get pubkey
+          const pubkey = await getPublicKey()
+
+          // 3. Fetch profile (best-effort)
+          const profile = await fetchNostrProfile(pubkey)
+
+          // 4. Build unsigned event (NIP-07 compatible)
+          const unsignedEvent = {
+            kind: 27235,
+            content: nonce,
+            created_at: Math.floor(Date.now() / 1000),
+            tags: [['u', window.location.origin]],
+          }
+
+          // 5. Sign via extension
+          const signed = await signEvent(unsignedEvent)
+
+          // 6. Verify with server
+          const data = await api.nostrVerify({
+            signed_event: JSON.stringify(signed),
+            challenge,
+            profile_name: profile?.name || null,
+            profile_picture: profile?.picture || null,
+          })
+
+          this.props.cbLogin(data)
+        } catch (err) {
+          this.update({ error: err.message || 'Nostr login failed', nostrLoading: false })
+        }
+      },
     }
   </script>
 </login-page>
diff --git a/client/src/components/profile-page.riot b/client/src/components/profile-page.riot
index a3e780c..278efaf 100644
--- a/client/src/components/profile-page.riot
+++ b/client/src/components/profile-page.riot
@@ -41,8 +41,8 @@
 
         <div class="form-group">
           <label>Email</label>
-          <input type="email" value={props.user?.email} disabled class="input-disabled" />
-          <span class="form-hint">Email cannot be changed</span>
+          <input type="email" value={props.user?.email || 'Nostr user'} disabled class="input-disabled" />
+          <span class="form-hint">{props.user?.email ? 'Email cannot be changed' : 'Logged in via Nostr'}</span>
         </div>
 
         <p if={state.error} class="error-text">{state.error}</p>
diff --git a/client/src/components/register-page.riot b/client/src/components/register-page.riot
index 0058dff..b915293 100644
--- a/client/src/components/register-page.riot
+++ b/client/src/components/register-page.riot
@@ -51,6 +51,17 @@
         </button>
       </form>
 
+      <div if={state.hasNostr} class="nostr-divider">
+        <span>or</span>
+      </div>
+
+      <button if={state.hasNostr} class="btn btn-nostr btn-full" onclick={handleNostrLogin} disabled={state.nostrLoading}>
+        <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" style="margin-right: 8px; vertical-align: -2px;">
+          <path d="M21 2l-2 2m-7.61 7.61a5.5 5.5 0 1 1-7.778 7.778 5.5 5.5 0 0 1 7.777-7.777zm0 0L15.5 7.5m0 0l3 3L22 7l-3-3m-3.5 3.5L19 4"/>
+        </svg>
+        {state.nostrLoading ? 'Connecting...' : 'Sign up with Nostr'}
+      </button>
+
       <p class="auth-footer">
         Already have an account?
         <a href="#" onclick={e => { e.preventDefault(); props.cbSwitch() }}>Sign in</a>
@@ -117,6 +128,47 @@
       margin-bottom: var(--space-sm);
     }
 
+    .nostr-divider {
+      display: flex;
+      align-items: center;
+      gap: var(--space-md);
+      margin: var(--space-lg) 0;
+      color: var(--text-muted);
+      font-size: var(--text-sm);
+    }
+
+    .nostr-divider::before,
+    .nostr-divider::after {
+      content: '';
+      flex: 1;
+      height: 1px;
+      background: var(--border);
+    }
+
+    .btn-nostr {
+      background: #8B5CF6;
+      color: white;
+      border: none;
+      padding: var(--space-sm) var(--space-md);
+      border-radius: var(--radius-md);
+      font-size: var(--text-sm);
+      font-weight: 500;
+      cursor: pointer;
+      transition: background var(--transition-fast);
+      display: flex;
+      align-items: center;
+      justify-content: center;
+    }
+
+    .btn-nostr:hover:not(:disabled) {
+      background: #7C3AED;
+    }
+
+    .btn-nostr:disabled {
+      opacity: 0.6;
+      cursor: not-allowed;
+    }
+
     .auth-footer {
       text-align: center;
       margin-top: var(--space-lg);
@@ -127,6 +179,7 @@
 
   <script>
     import { api } from '../services/api.js'
+    import { hasNostrExtension, getPublicKey, signEvent, fetchNostrProfile } from '../services/nostr.js'
 
     export default {
       state: {
@@ -135,6 +188,14 @@
         password: '',
         error: null,
         loading: false,
+        hasNostr: false,
+        nostrLoading: false,
+      },
+
+      onMounted() {
+        setTimeout(() => {
+          this.update({ hasNostr: hasNostrExtension() })
+        }, 100)
       },
 
       async handleSubmit(e) {
@@ -152,6 +213,38 @@
           this.update({ error: err.message, loading: false })
         }
       },
+
+      async handleNostrLogin() {
+        this.update({ nostrLoading: true, error: null })
+
+        try {
+          const { challenge } = await api.nostrChallenge()
+          const nonce = JSON.parse(atob(challenge.split('.')[1])).nonce
+          const pubkey = await getPublicKey()
+          const profile = await fetchNostrProfile(pubkey)
+
+          const unsignedEvent = {
+            kind: 27235,
+            content: nonce,
+            created_at: Math.floor(Date.now() / 1000),
+            tags: [['u', window.location.origin]],
+          }
+
+          const signed = await signEvent(unsignedEvent)
+
+          const data = await api.nostrVerify({
+            signed_event: JSON.stringify(signed),
+            challenge,
+            profile_name: profile?.name || null,
+            profile_picture: profile?.picture || null,
+          })
+
+          // Nostr login auto-creates — use same callback as register
+          this.props.cbRegister(data)
+        } catch (err) {
+          this.update({ error: err.message || 'Nostr login failed', nostrLoading: false })
+        }
+      },
     }
   </script>
 </register-page>
diff --git a/client/src/services/api.js b/client/src/services/api.js
index 2148d7a..96894e2 100644
--- a/client/src/services/api.js
+++ b/client/src/services/api.js
@@ -33,7 +33,7 @@ async function request(method, path, body) {
 
   if (!res.ok) {
     // Auto-logout on 401 for any authenticated request (not login/register)
-    if (res.status === 401 && path !== '/auth/login' && path !== '/auth/register') {
+    if (res.status === 401 && path !== '/auth/login' && path !== '/auth/register' && path !== '/auth/nostr/verify') {
       if (onUnauthorized) onUnauthorized()
       throw new Error('Session expired — please log in again')
     }
@@ -110,6 +110,11 @@ export const api = {
   // Invites
   createInvite: (data) => request('POST', '/invites', data),
   acceptInvite: (token) => request('POST', `/invites/${token}/accept`),
+  inviteByNostr: (data) => request('POST', '/invites/nostr', data),
+
+  // Nostr auth
+  nostrChallenge: () => request('GET', '/auth/nostr/challenge'),
+  nostrVerify: (data) => request('POST', '/auth/nostr/verify', data),
 }
 
 export function saveAuth(token, user) {
diff --git a/client/src/services/nostr.js b/client/src/services/nostr.js
new file mode 100644
index 0000000..b525513
--- /dev/null
+++ b/client/src/services/nostr.js
@@ -0,0 +1,75 @@
+/**
+ * NIP-07 browser extension helpers + relay profile fetch
+ */
+
+export function hasNostrExtension() {
+  return typeof window !== 'undefined' && !!window.nostr
+}
+
+export async function getPublicKey() {
+  return window.nostr.getPublicKey()
+}
+
+export async function signEvent(event) {
+  return window.nostr.signEvent(event)
+}
+
+/**
+ * Fetch a Nostr kind:0 profile from a relay via WebSocket.
+ * Returns { name, picture } or null on timeout/error.
+ */
+export function fetchNostrProfile(pubkeyHex, timeoutMs = 5000) {
+  return new Promise((resolve) => {
+    const relay = 'wss://relay.damus.io'
+    let ws
+    let timer
+
+    const cleanup = () => {
+      clearTimeout(timer)
+      try { ws?.close() } catch {}
+    }
+
+    timer = setTimeout(() => {
+      cleanup()
+      resolve(null)
+    }, timeoutMs)
+
+    try {
+      ws = new WebSocket(relay)
+    } catch {
+      cleanup()
+      resolve(null)
+      return
+    }
+
+    ws.onopen = () => {
+      const subId = 'profile_' + Math.random().toString(36).slice(2, 8)
+      ws.send(JSON.stringify(['REQ', subId, { kinds: [0], authors: [pubkeyHex], limit: 1 }]))
+    }
+
+    ws.onmessage = (msg) => {
+      try {
+        const data = JSON.parse(msg.data)
+        if (data[0] === 'EVENT' && data[2]?.kind === 0) {
+          const profile = JSON.parse(data[2].content)
+          cleanup()
+          resolve({
+            name: profile.name || profile.display_name || null,
+            picture: profile.picture || null,
+          })
+        } else if (data[0] === 'EOSE') {
+          // End of stored events — no profile found
+          cleanup()
+          resolve(null)
+        }
+      } catch {
+        // ignore parse errors, wait for timeout
+      }
+    }
+
+    ws.onerror = () => {
+      cleanup()
+      resolve(null)
+    }
+  })
+}
diff --git a/server/Cargo.lock b/server/Cargo.lock
index 644ace4..2714a0a 100644
--- a/server/Cargo.lock
+++ b/server/Cargo.lock
@@ -8,6 +8,16 @@ version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "320119579fcad9c21884f5c4861d16174d0e06250625266f50fe6898340abefa"
 
+[[package]]
+name = "aead"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d122413f284cf2d62fb1b7db97e02edb8cda96d769b16e443a4f6195e35662b0"
+dependencies = [
+ "crypto-common",
+ "generic-array",
+]
+
 [[package]]
 name = "ahash"
 version = "0.8.12"
@@ -78,6 +88,12 @@ dependencies = [
  "password-hash",
 ]
 
+[[package]]
+name = "arrayvec"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7c02d123df017efcdfbd739ef81735b36c5ba83ec3c59c80a9d7ecc718f92e50"
+
 [[package]]
 name = "async-compression"
 version = "0.4.41"
@@ -235,6 +251,40 @@ version = "1.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2af50177e190e07a26ab74f8b1efbfe2ef87da2116221318cb1c2e82baf7de06"
 
+[[package]]
+name = "bech32"
+version = "0.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32637268377fc7b10a8c6d51de3e7fba1ce5dd371a96e342b34e6078db558e7f"
+
+[[package]]
+name = "bip39"
+version = "2.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "90dbd31c98227229239363921e60fcf5e558e43ec69094d46fc4996f08d1d5bc"
+dependencies = [
+ "bitcoin_hashes",
+ "serde",
+ "unicode-normalization",
+]
+
+[[package]]
+name = "bitcoin-io"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2dee39a0ee5b4095224a0cfc6bf4cc1baf0f9624b96b367e53b66d974e51d953"
+
+[[package]]
+name = "bitcoin_hashes"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "26ec84b80c482df901772e931a9a681e26a1b9ee2302edeff23cb30328745c8b"
+dependencies = [
+ "bitcoin-io",
+ "hex-conservative",
+ "serde",
+]
+
 [[package]]
 name = "bitflags"
 version = "2.11.0"
@@ -262,6 +312,15 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "block-padding"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a8894febbff9f758034a5b8e12d87918f56dfc64a8e1fe757d65e29041538d93"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "brotli"
 version = "8.0.2"
@@ -301,6 +360,15 @@ version = "1.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1e748733b7cbc798e1434b6ac524f0c1ff2ab456fe201501e6497c8417a4fc33"
 
+[[package]]
+name = "cbc"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "26b52a9543ae338f279b96b0b9fed9c8093744685043739079ce85cd58f289a6"
+dependencies = [
+ "cipher",
+]
+
 [[package]]
 name = "cc"
 version = "1.2.56"
@@ -317,6 +385,30 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
+[[package]]
+name = "chacha20"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3613f74bd2eac03dad61bd53dbe620703d4371614fe0bc3b9f04dd36fe4e818"
+dependencies = [
+ "cfg-if",
+ "cipher",
+ "cpufeatures",
+]
+
+[[package]]
+name = "chacha20poly1305"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10cd79432192d1c0f4e1a0fef9527696cc039165d729fb41b3f4f4f354c2dc35"
+dependencies = [
+ "aead",
+ "chacha20",
+ "cipher",
+ "poly1305",
+ "zeroize",
+]
+
 [[package]]
 name = "chrono"
 version = "0.4.44"
@@ -331,6 +423,17 @@ dependencies = [
  "windows-link",
 ]
 
+[[package]]
+name = "cipher"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "773f3b9af64447d2ce9850330c473515014aa235e6a783b02db81ff39e4a3dad"
+dependencies = [
+ "crypto-common",
+ "inout",
+ "zeroize",
+]
+
 [[package]]
 name = "compression-codecs"
 version = "0.4.37"
@@ -436,6 +539,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78c8292055d1c1df0cce5d180393dc8cce0abec0a7102adb6c7b1eef6016d60a"
 dependencies = [
  "generic-array",
+ "rand_core",
  "typenum",
 ]
 
@@ -858,6 +962,7 @@ dependencies = [
  "futures",
  "jsonwebtoken",
  "md-5",
+ "nostr",
  "rand",
  "reqwest",
  "scraper",
@@ -971,6 +1076,15 @@ version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
+[[package]]
+name = "hex-conservative"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fda06d18ac606267c40c04e41b9947729bf8b9efe74bd4e82b61a5f26a510b9f"
+dependencies = [
+ "arrayvec",
+]
+
 [[package]]
 name = "hkdf"
 version = "0.12.4"
@@ -1285,6 +1399,28 @@ dependencies = [
  "serde_core",
 ]
 
+[[package]]
+name = "inout"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "879f10e63c20629ecabbb64a8010319738c66a5cd0c29b02d63d272b03751d01"
+dependencies = [
+ "block-padding",
+ "generic-array",
+]
+
+[[package]]
+name = "instant"
+version = "0.1.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e0242819d153cba4b4b05a5a8f2a7e9bbf97b6055b2a002b395c96b5ff3c0222"
+dependencies = [
+ "cfg-if",
+ "js-sys",
+ "wasm-bindgen",
+ "web-sys",
+]
+
 [[package]]
 name = "ipnet"
 version = "2.12.0"
@@ -1564,6 +1700,30 @@ dependencies = [
  "minimal-lexical",
 ]
 
+[[package]]
+name = "nostr"
+version = "0.44.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3aa5e3b6a278ed061835fe1ee293b71641e6bf8b401cfe4e1834bbf4ef0a34e1"
+dependencies = [
+ "base64 0.22.1",
+ "bech32",
+ "bip39",
+ "bitcoin_hashes",
+ "cbc",
+ "chacha20",
+ "chacha20poly1305",
+ "getrandom 0.2.17",
+ "hex",
+ "instant",
+ "scrypt",
+ "secp256k1",
+ "serde",
+ "serde_json",
+ "unicode-normalization",
+ "url",
+]
+
 [[package]]
 name = "nu-ansi-term"
 version = "0.50.3"
@@ -1641,6 +1801,12 @@ version = "1.21.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "42f5e15c9953c5e4ccceeb2e7382a716482c34515315f7b03532b8b4e8393d2d"
 
+[[package]]
+name = "opaque-debug"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c08d65885ee38876c4f86fa503fb49d7b507c2b62552df7c70b2fce627e06381"
+
 [[package]]
 name = "openssl"
 version = "0.10.75"
@@ -1725,6 +1891,16 @@ version = "1.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "57c0d7b74b563b49d38dae00a0c37d4d6de9b432382b2892f0574ddcae73fd0a"
 
+[[package]]
+name = "pbkdf2"
+version = "0.12.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8ed6a7761f76e3b9f92dfb0a60a6a6477c61024b775147ff0973a02653abaf2"
+dependencies = [
+ "digest",
+ "hmac",
+]
+
 [[package]]
 name = "pem"
 version = "3.0.6"
@@ -1847,6 +2023,17 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6"
 
+[[package]]
+name = "poly1305"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8159bd90725d2df49889a078b54f4f79e87f1f8a8444194cdca81d38f5393abf"
+dependencies = [
+ "cpufeatures",
+ "opaque-debug",
+ "universal-hash",
+]
+
 [[package]]
 name = "potential_utf"
 version = "0.1.4"
@@ -2117,6 +2304,15 @@ version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9774ba4a74de5f7b1c1451ed6cd5285a32eddb5cccb8cc655a4e50009e06477f"
 
+[[package]]
+name = "salsa20"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97a22f5af31f73a954c10289c93e8a50cc23d971e80ee446f1f6f7137a088213"
+dependencies = [
+ "cipher",
+]
+
 [[package]]
 name = "schannel"
 version = "0.1.28"
@@ -2147,6 +2343,38 @@ dependencies = [
  "tendril",
 ]
 
+[[package]]
+name = "scrypt"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0516a385866c09368f0b5bcd1caff3366aace790fcd46e2bb032697bb172fd1f"
+dependencies = [
+ "password-hash",
+ "pbkdf2",
+ "salsa20",
+ "sha2",
+]
+
+[[package]]
+name = "secp256k1"
+version = "0.29.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9465315bc9d4566e1724f0fffcbcc446268cb522e60f9a27bcded6b19c108113"
+dependencies = [
+ "rand",
+ "secp256k1-sys",
+ "serde",
+]
+
+[[package]]
+name = "secp256k1-sys"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d4387882333d3aa8cb20530a17c69a3752e97837832f34f6dccc760e715001d9"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "security-framework"
 version = "3.7.0"
@@ -3164,6 +3392,16 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "39ec24b3121d976906ece63c9daad25b85969647682eee313cb5779fdd69e14e"
 
+[[package]]
+name = "universal-hash"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc1de2c688dc15305988b563c3854064043356019f97a4b46276fe734c4f07ea"
+dependencies = [
+ "crypto-common",
+ "subtle",
+]
+
 [[package]]
 name = "untrusted"
 version = "0.9.0"
@@ -3180,6 +3418,7 @@ dependencies = [
  "idna",
  "percent-encoding",
  "serde",
+ "serde_derive",
 ]
 
 [[package]]
diff --git a/server/Cargo.toml b/server/Cargo.toml
index b8046ce..7067a3a 100644
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -27,3 +27,4 @@ scraper = "0.22"
 md-5 = "0.10"
 sha2 = "0.10"
 base64 = "0.22"
+nostr = { version = "0.44", default-features = false, features = ["std"] }
diff --git a/server/migrations/008_nostr.sql b/server/migrations/008_nostr.sql
new file mode 100644
index 0000000..eb98676
--- /dev/null
+++ b/server/migrations/008_nostr.sql
@@ -0,0 +1 @@
+ALTER TABLE users ADD COLUMN nostr_pubkey TEXT UNIQUE;
diff --git a/server/src/handlers/auth.rs b/server/src/handlers/auth.rs
index 49e0d05..18338c0 100644
--- a/server/src/handlers/auth.rs
+++ b/server/src/handlers/auth.rs
@@ -8,7 +8,7 @@ use uuid::Uuid;
 
 use crate::{
     middleware::auth::{create_token, AuthUser},
-    models::{AuthResponse, LoginRequest, RegisterRequest, UserPublic},
+    models::{self, AuthResponse, LoginRequest, RegisterRequest, UserPublic},
     AppState,
 };
 
@@ -61,7 +61,7 @@ pub async fn register(
         token,
         user: UserPublic {
             id: user_id,
-            email,
+            email: models::public_email(&email),
             display_name,
             avatar_url: None,
         },
@@ -100,7 +100,7 @@ pub async fn login(
         token,
         user: UserPublic {
             id: user_id,
-            email,
+            email: models::public_email(&email),
             display_name,
             avatar_url,
         },
@@ -121,7 +121,7 @@ pub async fn me(
 
     Ok(Json(UserPublic {
         id: auth.user_id,
-        email: auth.email,
+        email: models::public_email(&auth.email),
         display_name: auth.display_name,
         avatar_url,
     }))
diff --git a/server/src/handlers/invites.rs b/server/src/handlers/invites.rs
index f7e24c9..157e883 100644
--- a/server/src/handlers/invites.rs
+++ b/server/src/handlers/invites.rs
@@ -9,7 +9,7 @@ use uuid::Uuid;
 
 use crate::{
     middleware::auth::AuthUser,
-    models::CreateInviteRequest,
+    models::{CreateInviteRequest, NostrInviteRequest},
     AppState,
 };
 
@@ -118,3 +118,73 @@ pub async fn accept_invite(
 
     Ok(Json(AcceptInviteResponse { room_id }))
 }
+
+#[derive(serde::Serialize)]
+pub struct NostrInviteResponse {
+    pub status: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub display_name: Option<String>,
+}
+
+pub async fn invite_by_nostr(
+    State(state): State<Arc<AppState>>,
+    auth: AuthUser,
+    Json(body): Json<NostrInviteRequest>,
+) -> Result<Json<NostrInviteResponse>, (StatusCode, String)> {
+    // Normalize pubkey: if it starts with "npub", decode bech32
+    let pubkey_hex = if body.nostr_pubkey.starts_with("npub") {
+        nostr::prelude::PublicKey::parse(&body.nostr_pubkey)
+            .map(|pk| pk.to_hex())
+            .map_err(|_| (StatusCode::BAD_REQUEST, "Invalid npub format".to_string()))?
+    } else {
+        // Validate it's valid hex
+        if body.nostr_pubkey.len() != 64 || !body.nostr_pubkey.chars().all(|c| c.is_ascii_hexdigit()) {
+            return Err((StatusCode::BAD_REQUEST, "Invalid pubkey: must be 64-char hex or npub".to_string()));
+        }
+        body.nostr_pubkey.clone()
+    };
+
+    // Verify inviter is a member of the room
+    let is_member = sqlx::query_scalar::<_, String>(
+        "SELECT user_id FROM room_members WHERE room_id = ? AND user_id = ?",
+    )
+    .bind(&body.room_id)
+    .bind(&auth.user_id)
+    .fetch_optional(&state.db)
+    .await
+    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
+
+    if is_member.is_none() {
+        return Err((StatusCode::FORBIDDEN, "Not a member of this room".into()));
+    }
+
+    // Lookup user by nostr_pubkey
+    let target_user = sqlx::query_as::<_, (String, String)>(
+        "SELECT id, display_name FROM users WHERE nostr_pubkey = ?",
+    )
+    .bind(&pubkey_hex)
+    .fetch_optional(&state.db)
+    .await
+    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
+
+    match target_user {
+        Some((user_id, display_name)) => {
+            // Add to room
+            sqlx::query("INSERT OR IGNORE INTO room_members (room_id, user_id) VALUES (?, ?)")
+                .bind(&body.room_id)
+                .bind(&user_id)
+                .execute(&state.db)
+                .await
+                .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
+
+            Ok(Json(NostrInviteResponse {
+                status: "added".to_string(),
+                display_name: Some(display_name),
+            }))
+        }
+        None => Ok(Json(NostrInviteResponse {
+            status: "not_found".to_string(),
+            display_name: None,
+        })),
+    }
+}
diff --git a/server/src/handlers/mod.rs b/server/src/handlers/mod.rs
index ff74873..2861e62 100644
--- a/server/src/handlers/mod.rs
+++ b/server/src/handlers/mod.rs
@@ -1,6 +1,7 @@
 pub mod auth;
 pub mod invites;
 pub mod models;
+pub mod nostr_auth;
 pub mod profile;
 pub mod rooms;
 pub mod upload;
diff --git a/server/src/handlers/nostr_auth.rs b/server/src/handlers/nostr_auth.rs
new file mode 100644
index 0000000..c238839
--- /dev/null
+++ b/server/src/handlers/nostr_auth.rs
@@ -0,0 +1,167 @@
+use axum::{extract::State, http::StatusCode, Json};
+use jsonwebtoken::{decode, encode, DecodingKey, EncodingKey, Header, Validation};
+use nostr::prelude::*;
+use std::sync::Arc;
+use uuid::Uuid;
+
+use crate::{
+    middleware::auth::create_token,
+    models::{AuthResponse, NostrChallengeResponse, NostrVerifyRequest, UserPublic},
+    AppState,
+};
+
+#[derive(Debug, serde::Serialize, serde::Deserialize)]
+struct ChallengeClaims {
+    pub nonce: String,
+    pub exp: usize,
+}
+
+/// GET /api/auth/nostr/challenge — return a short-lived JWT containing a random nonce
+pub async fn challenge(
+    State(state): State<Arc<AppState>>,
+) -> Result<Json<NostrChallengeResponse>, (StatusCode, String)> {
+    // Generate 32 random bytes as hex nonce
+    let mut nonce_bytes = [0u8; 32];
+    use rand::RngCore;
+    rand::thread_rng().fill_bytes(&mut nonce_bytes);
+    let nonce = hex::encode(&nonce_bytes);
+
+    let exp = (chrono::Utc::now().timestamp() + 120) as usize; // 2 minutes
+
+    let claims = ChallengeClaims {
+        nonce,
+        exp,
+    };
+
+    let token = encode(
+        &Header::default(),
+        &claims,
+        &EncodingKey::from_secret(state.jwt_secret.as_bytes()),
+    )
+    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
+
+    Ok(Json(NostrChallengeResponse { challenge: token }))
+}
+
+/// Simple hex encoder (avoid adding the `hex` crate just for this)
+mod hex {
+    pub fn encode(bytes: &[u8]) -> String {
+        bytes.iter().map(|b| format!("{:02x}", b)).collect()
+    }
+}
+
+/// POST /api/auth/nostr/verify — verify signed event, create/login user
+pub async fn verify(
+    State(state): State<Arc<AppState>>,
+    Json(body): Json<NostrVerifyRequest>,
+) -> Result<Json<AuthResponse>, (StatusCode, String)> {
+    // 1. Decode challenge JWT, verify not expired, extract nonce
+    let challenge_data = decode::<ChallengeClaims>(
+        &body.challenge,
+        &DecodingKey::from_secret(state.jwt_secret.as_bytes()),
+        &Validation::default(),
+    )
+    .map_err(|_| (StatusCode::BAD_REQUEST, "Invalid or expired challenge".to_string()))?;
+
+    let nonce = &challenge_data.claims.nonce;
+
+    // 2. Deserialize signed_event as nostr::Event
+    let event: Event = serde_json::from_str(&body.signed_event)
+        .map_err(|e| (StatusCode::BAD_REQUEST, format!("Invalid event JSON: {}", e)))?;
+
+    // 3. Verify Schnorr signature
+    if !event.verify_signature() {
+        return Err((StatusCode::UNAUTHORIZED, "Invalid event signature".to_string()));
+    }
+
+    // 4. Verify event.content == nonce
+    if event.content.as_str() != nonce.as_str() {
+        return Err((StatusCode::BAD_REQUEST, "Nonce mismatch".to_string()));
+    }
+
+    // 5. Verify event.created_at within 5 minutes
+    let now = chrono::Utc::now().timestamp() as u64;
+    let event_ts = event.created_at.as_secs();
+    if now.abs_diff(event_ts) > 300 {
+        return Err((StatusCode::BAD_REQUEST, "Event timestamp too far off".to_string()));
+    }
+
+    // 6. Extract pubkey hex
+    let pubkey_hex = event.pubkey.to_hex();
+
+    // 7. Lookup user by nostr_pubkey
+    let existing = sqlx::query_as::<_, (String, String, String, Option<String>)>(
+        "SELECT id, email, display_name, avatar_url FROM users WHERE nostr_pubkey = ?",
+    )
+    .bind(&pubkey_hex)
+    .fetch_optional(&state.db)
+    .await
+    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
+
+    let (user_id, email, display_name, avatar_url) = if let Some(user) = existing {
+        // Update avatar if provided and user doesn't have a custom one
+        if let Some(ref pic) = body.profile_picture {
+            if user.3.is_none() || user.3.as_deref() == Some("") {
+                let _ = sqlx::query("UPDATE users SET avatar_url = ? WHERE id = ?")
+                    .bind(pic)
+                    .bind(&user.0)
+                    .execute(&state.db)
+                    .await;
+                (user.0, user.1, user.2, Some(pic.clone()))
+            } else {
+                user
+            }
+        } else {
+            user
+        }
+    } else {
+        // Create new user
+        let user_id = Uuid::new_v4().to_string();
+        let sentinel_email = format!("nostr:{}", &pubkey_hex[..16]);
+        let display_name = body
+            .profile_name
+            .clone()
+            .filter(|n| !n.trim().is_empty())
+            .unwrap_or_else(|| {
+                let npub = PublicKey::from_hex(&pubkey_hex)
+                    .map(|pk| pk.to_bech32().unwrap_or_default())
+                    .unwrap_or_default();
+                if npub.len() > 8 {
+                    format!("npub...{}", &npub[npub.len() - 8..])
+                } else {
+                    format!("nostr-{}", &pubkey_hex[..8])
+                }
+            });
+
+        let avatar_url = body.profile_picture.clone();
+
+        sqlx::query(
+            "INSERT INTO users (id, email, display_name, password_hash, nostr_pubkey, avatar_url) VALUES (?, ?, ?, ?, ?, ?)",
+        )
+        .bind(&user_id)
+        .bind(&sentinel_email)
+        .bind(&display_name)
+        .bind("")
+        .bind(&pubkey_hex)
+        .bind(&avatar_url)
+        .execute(&state.db)
+        .await
+        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
+
+        (user_id, sentinel_email, display_name, avatar_url)
+    };
+
+    // 8. Issue JWT, return AuthResponse
+    let token = create_token(&user_id, &email, &display_name, &state.jwt_secret)
+        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
+
+    Ok(Json(AuthResponse {
+        token,
+        user: UserPublic {
+            id: user_id,
+            email: crate::models::public_email(&email),
+            display_name,
+            avatar_url,
+        },
+    }))
+}
diff --git a/server/src/handlers/profile.rs b/server/src/handlers/profile.rs
index a0d3206..4ebce73 100644
--- a/server/src/handlers/profile.rs
+++ b/server/src/handlers/profile.rs
@@ -7,7 +7,7 @@ use std::sync::Arc;
 
 use crate::{
     middleware::auth::{create_token, AuthUser},
-    models::{AuthResponse, UserPublic},
+    models::{self, AuthResponse, UserPublic},
     AppState,
 };
 
@@ -52,7 +52,7 @@ pub async fn update_profile(
         token,
         user: UserPublic {
             id: auth.user_id,
-            email: auth.email,
+            email: models::public_email(&auth.email),
             display_name,
             avatar_url,
         },
@@ -136,7 +136,7 @@ pub async fn upload_avatar(
         token,
         user: UserPublic {
             id: auth.user_id,
-            email: auth.email,
+            email: models::public_email(&auth.email),
             display_name: auth.display_name,
             avatar_url: Some(avatar_url),
         },
@@ -173,7 +173,7 @@ pub async fn delete_avatar(
         token,
         user: UserPublic {
             id: auth.user_id,
-            email: auth.email,
+            email: models::public_email(&auth.email),
             display_name: auth.display_name,
             avatar_url: None,
         },
diff --git a/server/src/handlers/rooms.rs b/server/src/handlers/rooms.rs
index c742751..f4468d8 100644
--- a/server/src/handlers/rooms.rs
+++ b/server/src/handlers/rooms.rs
@@ -8,7 +8,7 @@ use uuid::Uuid;
 
 use crate::{
     middleware::auth::AuthUser,
-    models::{CreateRoomRequest, MessagePayload, PaginationParams, Room, RoomResponse, UserPublic},
+    models::{self, CreateRoomRequest, MessagePayload, PaginationParams, Room, RoomResponse, UserPublic},
     AppState,
 };
 
@@ -52,7 +52,7 @@ pub async fn create_room(
         created_at: chrono::Utc::now().to_rfc3339(),
         members: vec![UserPublic {
             id: auth.user_id,
-            email: auth.email,
+            email: models::public_email(&auth.email),
             display_name: auth.display_name,
             avatar_url: None,
         }],
@@ -94,7 +94,7 @@ pub async fn list_rooms(
                 .into_iter()
                 .map(|(id, email, display_name, avatar_url)| UserPublic {
                     id,
-                    email,
+                    email: models::public_email(&email),
                     display_name,
                     avatar_url,
                 })
diff --git a/server/src/main.rs b/server/src/main.rs
index 8f8d3f7..5ef29fe 100644
--- a/server/src/main.rs
+++ b/server/src/main.rs
@@ -253,6 +253,16 @@ async fn main() {
         Err(e) => panic!("Failed to run migration 007: {}", e),
     }
 
+    // Run migration 008 - nostr pubkey on users
+    let migration_008 = include_str!("../migrations/008_nostr.sql");
+    match sqlx::raw_sql(migration_008).execute(&db).await {
+        Ok(_) => tracing::info!("Migration 008 applied"),
+        Err(e) if e.to_string().contains("duplicate column") => {
+            tracing::debug!("Migration 008 already applied, skipping");
+        }
+        Err(e) => panic!("Failed to run migration 008: {}", e),
+    }
+
     tracing::info!("Database initialized");
 
     let (tx, _rx) = broadcast::channel::<models::BroadcastEvent>(4096);
@@ -278,6 +288,9 @@ async fn main() {
         .route("/api/auth/register", post(handlers::auth::register))
         .route("/api/auth/login", post(handlers::auth::login))
         .route("/api/auth/me", get(handlers::auth::me))
+        // Nostr auth routes
+        .route("/api/auth/nostr/challenge", get(handlers::nostr_auth::challenge))
+        .route("/api/auth/nostr/verify", post(handlers::nostr_auth::verify))
         // Profile routes
         .route("/api/auth/profile", put(handlers::profile::update_profile))
         .route("/api/auth/avatar", post(handlers::profile::upload_avatar).delete(handlers::profile::delete_avatar))
@@ -295,6 +308,7 @@ async fn main() {
         // Invite routes
         .route("/api/invites", post(handlers::invites::create_invite))
         .route("/api/invites/:token/accept", post(handlers::invites::accept_invite))
+        .route("/api/invites/nostr", post(handlers::invites::invite_by_nostr))
         // Uploaded files (avatars)
         .nest_service("/uploads", ServeDir::new("uploads"))
         // WebSocket
diff --git a/server/src/models/mod.rs b/server/src/models/mod.rs
index 544c096..6fe7479 100644
--- a/server/src/models/mod.rs
+++ b/server/src/models/mod.rs
@@ -285,3 +285,33 @@ pub struct PaginationParams {
 fn default_limit() -> i64 {
     50
 }
+
+/// Returns "" if the email is a sentinel nostr: value, otherwise returns it as-is.
+pub fn public_email(email: &str) -> String {
+    if email.starts_with("nostr:") {
+        String::new()
+    } else {
+        email.to_string()
+    }
+}
+
+// ── Nostr auth types ──
+
+#[derive(Debug, Serialize)]
+pub struct NostrChallengeResponse {
+    pub challenge: String,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct NostrVerifyRequest {
+    pub signed_event: String,
+    pub challenge: String,
+    pub profile_name: Option<String>,
+    pub profile_picture: Option<String>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct NostrInviteRequest {
+    pub room_id: String,
+    pub nostr_pubkey: String,
+}