diff --git a/api/src/api/scope.rs b/api/src/api/scope.rs
index 3826b825..7386f49a 100644
--- a/api/src/api/scope.rs
+++ b/api/src/api/scope.rs
@@ -219,7 +219,7 @@ async fn invite_member_handler(
   let scope = req.param_scope()?;
   Span::current().record("scope", &field::display(&scope));
 
-  let ApiAddScopeMemberRequest { github_login } = decode_json(&mut req).await?;
+  let invite = decode_json::<ApiAddScopeMemberRequest>(&mut req).await?;
 
   let iam = req.iam();
   let current_user = iam.check_current_user_access()?.to_owned();
@@ -232,14 +232,21 @@ async fn invite_member_handler(
   let iam = req.iam();
   iam.check_scope_admin_access(&scope).await?;
 
-  let new_user = lookup_user_by_github_login(
-    db,
-    github_oauth2_client,
-    &current_user,
-    &github_login,
-  )
-  .await?
-  .ok_or(ApiError::UserNotFound)?;
+  let new_user = match invite {
+    ApiAddScopeMemberRequest::GithubLogin(github_login) => {
+      lookup_user_by_github_login(
+        db,
+        github_oauth2_client,
+        &current_user,
+        &github_login,
+      )
+      .await?
+      .ok_or(ApiError::UserNotFound)?
+    }
+    ApiAddScopeMemberRequest::Id(id) => {
+      db.get_user(id).await?.ok_or(ApiError::UserNotFound)?
+    }
+  };
 
   if db.get_scope_member(&scope, new_user.id).await?.is_some() {
     return Err(ApiError::AlreadyScopeMember);
diff --git a/api/src/api/types.rs b/api/src/api/types.rs
index 93289625..4572d2c8 100644
--- a/api/src/api/types.rs
+++ b/api/src/api/types.rs
@@ -283,8 +283,9 @@ impl From<(ScopeMember, UserPublic)> for ApiScopeMember {
 
 #[derive(Debug, Deserialize)]
 #[serde(rename_all = "camelCase")]
-pub struct ApiAddScopeMemberRequest {
-  pub github_login: String,
+pub enum ApiAddScopeMemberRequest {
+  GithubLogin(String),
+  Id(Uuid),
 }
 
 #[derive(Debug, Deserialize)]
diff --git a/frontend/routes/@[scope]/(_islands)/ScopeInviteForm.tsx b/frontend/routes/@[scope]/(_islands)/ScopeInviteForm.tsx
index 110b60b3..cb53425c 100644
--- a/frontend/routes/@[scope]/(_islands)/ScopeInviteForm.tsx
+++ b/frontend/routes/@[scope]/(_islands)/ScopeInviteForm.tsx
@@ -1,6 +1,6 @@
 // Copyright 2024 the JSR authors. All rights reserved. MIT license.
 import { useSignal } from "@preact/signals";
-import { useCallback } from "preact/hooks";
+import { useCallback, useRef } from "preact/hooks";
 import { JSX } from "preact/jsx-runtime";
 import { ScopeInvite } from "../../../utils/api_types.ts";
 import { api, path } from "../../../utils/api.ts";
@@ -12,18 +12,25 @@ interface ScopeInviteFormProps {
 export function ScopeInviteForm(props: ScopeInviteFormProps) {
   const submitting = useSignal(false);
   const error = useSignal<string>("");
+  const kind = useSignal<"github" | "id">("github");
+  const inputRef = useRef<HTMLInputElement>(null);
 
   const onSubmit = useCallback(
     (e: JSX.TargetedEvent<HTMLFormElement>) => {
       e.preventDefault();
       const formData = new FormData(e.currentTarget);
-      const githubLogin = String(formData.get("githubLogin"));
+
+      const kind = String(formData.get("kind"));
+      const inviteValue = String(formData.get("inviteValue"));
 
       submitting.value = true;
 
       api.post<ScopeInvite>(
         path`/scopes/${props.scope}/members`,
-        { githubLogin },
+        {
+          githubLogin: kind === "github" ? inviteValue : undefined,
+          id: kind === "id" ? inviteValue : undefined,
+        },
       ).then((res) => {
         submitting.value = false;
         if (!res.ok) {
@@ -47,14 +54,36 @@ export function ScopeInviteForm(props: ScopeInviteFormProps) {
       onSubmit={onSubmit}
     >
       <div class="mt-4 flex gap-4">
-        <input
-          class="block w-full max-w-sm px-3 input-container text-sm input"
-          type="text"
-          name="githubLogin"
-          placeholder="GitHub username"
-          required
-          disabled={submitting}
-        />
+        <div class="flex">
+          <select
+            name="kind"
+            id="kind-select"
+            class="inline-block p-1.5 input-container input rounded-r-none border-r-0"
+            disabled={submitting}
+            onChange={(e) => {
+              if (kind.value !== e.currentTarget.value) {
+                kind.value = e.currentTarget.value as "github" | "id";
+                if (inputRef?.current) {
+                  inputRef.current.value = "";
+                }
+              }
+            }}
+          >
+            <option value="github" selected>GitHub</option>
+            <option value="id">User ID</option>
+          </select>
+          <input
+            class="inline-block w-full max-w-sm px-3 input-container text-sm input rounded-l-none"
+            type="text"
+            name="inviteValue"
+            placeholder={kind.value === "github"
+              ? "GitHub username"
+              : "User ID"}
+            required
+            ref={inputRef}
+            disabled={submitting}
+          />
+        </div>
         <button
           class="button-primary"
           type="submit"