OpenConceptLab · snyaggarwal · Apr 21, 2026
diff --git a/src/components/app/App.jsx b/src/components/app/App.jsx
@@ -10,19 +10,21 @@ import Error403 from '../errors/Error403';
 import Error401 from '../errors/Error401';
 import WaitListing from '../errors/WaitListing'
 import NetworkError from '../errors/NetworkError'
+import ThrottlingError from '../errors/ThrottlingError'
 import ErrorBoundary from '../errors/ErrorBoundary';
 import CheckAuth from './CheckAuth'
 import Footer from './Footer';
 import DocumentTitle from "./DocumentTitle"
 import './App.scss';
 import { hotjar } from 'react-hotjar';
-import APIService from '../../services/APIService'
+import APIService, { getThrottlingDetails } from '../../services/APIService'
 import Header from './Header';
 import OIDLoginCallback from '../users/OIDLoginCallback';
 import { OperationsContext } from './LayoutContext';
 import Alert from '../common/Alert';
 import MapProject from '../map-projects/MapProject'
 import MapProjects from '../map-projects/MapProjects'
+import { useTranslation } from 'react-i18next';
 
 const AuthenticationRequiredRoute = ({component: Component, ...rest}) => {
   const { toggles } = React.useContext(OperationsContext);
@@ -47,7 +49,9 @@ const AuthenticationRequiredRoute = ({component: Component, ...rest}) => {
 }
 
 const App = props => {
-  const [networkError, setNetworkError] = React.useState(false)
+  const { t } = useTranslation();
+  const [startupError, setStartupError] = React.useState(null)
+  const [throttlingError, setThrottlingError] = React.useState(null)
   const { alert, setAlert, setToggles } = React.useContext(OperationsContext);
   const setupHotJar = () => {
     /*eslint no-undef: 0*/
@@ -60,8 +64,8 @@ const App = props => {
     return new Promise(resolve => {
       APIService.toggles().get().then(response => {
         if(response === 'Network Error')
-          setNetworkError(true)
-        else {
+          setStartupError({ type: 'network' })
+        else if(response?.status !== 429) {
           setToggles(response.data)
           resolve();
         }
@@ -96,29 +100,56 @@ const App = props => {
   }
 
   React.useEffect(() => {
+    const unsubscribe = APIService.onThrottle(details => {
+      setThrottlingError(getThrottlingDetails(details.response || details))
+    })
+
     forceLoginUser()
     fetchToggles()
     addLogoutListenerForAllTabs()
     recordGAPageView()
     setupHotJar()
+
+    return () => unsubscribe()
   }, [])
 
+  const clearThrottlingError = React.useCallback(() => {
+    setThrottlingError(null)
+    setAlert({
+      severity: 'success',
+      message: t('errors.throttled.ended'),
+      duration: 4000,
+    })
+  }, [setAlert, t])
+
   return (
     <div>
       <DocumentTitle/>
       <Header>
         <ErrorBoundary>
           <main className='content'>
-            {networkError && <NetworkError />}
-            <Switch>
-              <Route exact path="/oidc/login" component={OIDLoginCallback} />
-              <AuthenticationRequiredRoute exact path='/' component={MapProjects} />
-              <AuthenticationRequiredRoute exact path='/map-projects' component={MapProjects} />
-              <AuthenticationRequiredRoute exact path='/map-projects/new' component={MapProject} />
-              <AuthenticationRequiredRoute exact path='/:ownerType/:owner/map-projects/:projectId' component={MapProject} />
-              <Route exact path='/403' component={Error403} />
-              <Route component={Error404} />
-            </Switch>
+            {startupError?.type === 'network' ? (
+              <NetworkError />
+            ) : (
+              <React.Fragment>
+                <Switch>
+                  <Route exact path="/oidc/login" component={OIDLoginCallback} />
+                  <AuthenticationRequiredRoute exact path='/' component={MapProjects} />
+                  <AuthenticationRequiredRoute exact path='/map-projects' component={MapProjects} />
+                  <AuthenticationRequiredRoute exact path='/map-projects/new' component={MapProject} />
+                  <AuthenticationRequiredRoute exact path='/:ownerType/:owner/map-projects/:projectId' component={MapProject} />
+                  <Route exact path='/403' component={Error403} />
+                  <Route component={Error404} />
+                </Switch>
+                {throttlingError && (
+                  <ThrottlingError
+                    retryAfter={throttlingError.retryAfter}
+                    limitType={throttlingError.limitType}
+                    onExpire={clearThrottlingError}
+                  />
+                )}
+              </React.Fragment>
+            )}
             <Alert message={alert?.message} onClose={() => setAlert(false)} severity={alert?.severity} duration={alert?.duration} />
           </main>
         </ErrorBoundary>
@@ -129,4 +160,3 @@ const App = props => {
 }
 
 export default withRouter(App);
-
diff --git a/src/components/errors/ThrottlingError.jsx b/src/components/errors/ThrottlingError.jsx
@@ -0,0 +1,79 @@
+import React from 'react';
+import { useTranslation } from 'react-i18next'
+
+const formatTime = totalSeconds => {
+  const safeSeconds = Math.max(totalSeconds, 0);
+  const minutes = Math.floor(safeSeconds / 60);
+  const seconds = safeSeconds % 60;
+  return `${String(minutes).padStart(2, '0')}:${String(seconds).padStart(2, '0')}`;
+}
+
+const getLimitMessage = (t, limitType) => {
+  if(limitType === 'minute')
+    return t('errors.throttled.limit_hit.minute');
+  if(limitType === 'day')
+    return t('errors.throttled.limit_hit.day');
+  if(limitType === 'minute_and_day')
+    return t('errors.throttled.limit_hit.minute_and_day');
+
+  return t('errors.throttled.limit_hit.unknown');
+}
+
+const ThrottlingError = ({
+  retryAfter = 0,
+  limitType = 'unknown',
+  onExpire,
+}) => {
+  const { t } = useTranslation()
+  const [secondsLeft, setSecondsLeft] = React.useState(Math.max(retryAfter, 0))
+
+  React.useEffect(() => {
+    setSecondsLeft(Math.max(retryAfter, 0))
+  }, [retryAfter])
+
+  React.useEffect(() => {
+    if(retryAfter <= 0 && onExpire)
+      onExpire()
+  }, [retryAfter, onExpire])
+
+  React.useEffect(() => {
+    if(secondsLeft <= 0)
+      return undefined;
+
+    const timer = window.setInterval(() => {
+      setSecondsLeft(currentSeconds => {
+        if(currentSeconds <= 1) {
+          window.clearInterval(timer)
+          if(onExpire)
+            onExpire()
+          return 0;
+        }
+
+        return currentSeconds - 1;
+      })
+    }, 1000)
+
+    return () => window.clearInterval(timer)
+  }, [secondsLeft])
+
+  return (
+    <div style={{position: 'fixed', inset: 0, zIndex: 1400, background: 'rgba(255, 255, 255, 0.6)', backdropFilter: 'blur(2px)', display: 'flex', alignItems: 'center', justifyContent: 'center', textAlign: 'center', flexDirection: 'column', padding: '24px'}}>
+      <div className='col-xs-12' style={{maxWidth: '560px'}}>
+        <p style={{color: '#000', fontSize: '24px', margin: '16px 0'}}>
+          {t('errors.throttled.title')}
+        </p>
+        <p style={{color: '#333', fontSize: '16px', margin: '0 0 12px'}}>
+          {getLimitMessage(t, limitType)}
+        </p>
+        <p style={{color: '#333', fontSize: '16px', margin: '0 0 12px'}}>
+          {t('errors.throttled.retry_after')}
+        </p>
+        <p style={{color: '#000', fontSize: '36px', fontWeight: 700, margin: '0'}}>
+          {formatTime(secondsLeft)}
+        </p>
+      </div>
+    </div>
+  )
+}
+
+export default ThrottlingError;
diff --git a/src/components/map-projects/MapProjects.jsx b/src/components/map-projects/MapProjects.jsx
@@ -37,7 +37,8 @@ const MapProjects = () => {
   const fetchOrgProjects = () => APIService.users(user.username).appendToUrl('orgs/map-projects/').get().then(handleProjectsResponse)
 
   const handleProjectsResponse = response => {
-    setProjects(prev => [...prev, ...(response?.data || [])])
+    const nextProjects = Array.isArray(response?.data) ? response.data : [];
+    setProjects(prev => [...prev, ...nextProjects])
     setLoading(prev => [...prev, false])
   }
 

diff --git a/src/i18n/locales/en/translations.json b/src/i18n/locales/en/translations.json
@@ -108,7 +108,18 @@
     "401": "Login is required",
     "403": "Access to this page is not authorized",
     "404": "Sorry your page could not be found.",
-    "network_error": "Network Error"
+    "network_error": "Network Error",
+    "throttled": {
+      "title": "Too many requests",
+      "retry_after": "This will disappear after:",
+      "ended": "Rate limit window ended. You can continue where you left off.",
+      "limit_hit": {
+        "minute": "The per-minute request limit has been reached.",
+        "day": "The daily request limit has been reached.",
+        "minute_and_day": "The per-minute and daily request limits have been reached",
+        "unknown": "A request limit has been reached."
+      }
+    }
   },
   "dashboard": {
     "name": "Dashboard",

diff --git a/src/i18n/locales/es/translations.json b/src/i18n/locales/es/translations.json
@@ -109,7 +109,18 @@
     "401": "Se requiere iniciar sesión",
     "403": "No tiene autorización para acceder a esta página",
     "404": "Lo siento, no se pudo encontrar tu página.",
-    "network_error": "Error de red"
+    "network_error": "Error de red",
+    "throttled": {
+      "title": "Demasiadas solicitudes",
+      "retry_after": "Esto desaparecerá después de:",
+      "ended": "La ventana del límite de solicitudes terminó. Puedes continuar donde lo dejaste.",
+      "limit_hit": {
+        "minute": "Se alcanzó el límite de solicitudes por minuto. Restante por minuto: {{minuteRemaining}}.",
+        "day": "Se alcanzó el límite diario de solicitudes. Restante del día: {{dayRemaining}}.",
+        "minute_and_day": "Se alcanzaron los límites de solicitudes por minuto y por día. Restante por minuto: {{minuteRemaining}}. Restante del día: {{dayRemaining}}.",
+        "unknown": "Se alcanzó un límite de solicitudes."
+      }
+    }
   },
   "dashboard": {
     "my": "Mi tablero",

diff --git a/src/i18n/locales/zh/translations.json b/src/i18n/locales/zh/translations.json
@@ -108,7 +108,18 @@
     "401": "需要登录",
     "403": "尚未获得访问该页面的权限",
     "404": "很抱歉，未能找到您的页面。",
-    "network_error": "网络错误"
+    "network_error": "网络错误",
+    "throttled": {
+      "title": "请求过多",
+      "retry_after": "此提示将在以下时间后消失：",
+      "ended": "请求限制窗口已结束。您可以从刚才的位置继续。",
+      "limit_hit": {
+        "minute": "已达到每分钟请求限制。当前分钟剩余：{{minuteRemaining}}。",
+        "day": "已达到每日请求限制。今日剩余：{{dayRemaining}}。",
+        "minute_and_day": "已达到每分钟和每日请求限制。当前分钟剩余：{{minuteRemaining}}。今日剩余：{{dayRemaining}}。",
+        "unknown": "已达到请求限制。"
+      }
+    }
   },
   "dashboard": {
     "name": "仪表盘",

diff --git a/src/services/APIService.js b/src/services/APIService.js
@@ -4,6 +4,7 @@ import {get, omit, isPlainObject, isString, defaults } from 'lodash';
 import { currentUserToken, getAPIURL, logoutUser } from '../common/utils';
 
 const APIServiceProvider = {};
+const throttlingListeners = new Set();
 const RESOURCES = [
   { name: 'concepts', relations: [] },
   { name: 'mappings', relations: [] },
@@ -19,6 +20,60 @@ const RESOURCES = [
   { name: 'new', relations: [] },
 ];
 
+const getHeaderValue = (headers = {}, key) => {
+  if(headers && typeof headers.get === 'function') {
+    const headerValue = headers.get(key) ?? headers.get(key.toLowerCase()) ?? headers.get(key.toUpperCase());
+    if(headerValue !== undefined && headerValue !== null)
+      return headerValue;
+  }
+
+  return headers?.[key] ?? headers?.[key.toLowerCase()] ?? headers?.[key.toUpperCase()];
+};
+
+export const getThrottlingDetails = response => {
+  const retryAfter = Number(getHeaderValue(response?.headers, 'retry-after'));
+  const minuteRemaining = Number(getHeaderValue(response?.headers, 'x-limitremaining-minute'));
+  const dayRemaining = Number(getHeaderValue(response?.headers, 'x-limitremaining-day'));
+  const hasMinuteRemaining = Number.isFinite(minuteRemaining);
+  const hasDayRemaining = Number.isFinite(dayRemaining);
+  let limitType = 'unknown';
+  if(hasMinuteRemaining && minuteRemaining <= 0 && hasDayRemaining && dayRemaining <= 0)
+    limitType = 'minute_and_day';
+  else if(hasMinuteRemaining && minuteRemaining <= 0)
+    limitType = 'minute';
+  else if(hasDayRemaining && dayRemaining <= 0)
+    limitType = 'day';
+
+  return {
+    retryAfter: Number.isFinite(retryAfter) && retryAfter > 0 ? retryAfter : 0,
+    limitType,
+    minuteRemaining: hasMinuteRemaining ? minuteRemaining : null,
+    dayRemaining: hasDayRemaining ? dayRemaining : null,
+    response,
+  };
+}
+
+const notifyThrottlingListeners = response => {
+  const details = getThrottlingDetails(response);
+  throttlingListeners.forEach(listener => listener(details));
+}
+
+const createPendingRequest = () => new Promise(() => {})
+
+const handleAPIError = (error, raw=false) => {
+  if(error?.response?.status === 401 && error?.response?.config?.url?.startsWith(getAPIURL())) {
+    logoutUser(true)
+    return { handled: true, result: undefined };
+  }
+
+  if(error?.response?.status === 429) {
+    notifyThrottlingListeners(error.response);
+    return { handled: true, result: raw ? error : createPendingRequest() };
+  }
+
+  return { handled: false };
+}
+
 class APIService {
   constructor(name, id, relations) {
     const apiURL = getAPIURL();
@@ -77,14 +132,14 @@ class APIService {
     return axios(request)
       .then(response => response || null)
       .catch(error => {
-        if(error?.response?.status === 401 && error?.response?.config?.url?.startsWith(getAPIURL())) {
-          logoutUser(true)
-        } else {
-          if(raw)
-            return error;
+        const { handled, result } = handleAPIError(error, raw);
+        if(handled)
+          return result;
 
-          return error.response ? error.response.data : error.message;
-        }
+        if(raw)
+          return error;
+
+        return error.response ? error.response.data : error.message;
 
       });
   }
@@ -108,7 +163,10 @@ class APIService {
     }
     let request = this.getRequest(method, data, token, headers, query);
     request = {...request, ...omit(config, ['headers', 'query'])};
-    return axios(request);
+    return axios(request).catch(error => {
+      handleAPIError(error);
+      return Promise.reject(error);
+    });
   };
 
   getHeaders(token, headers) {
@@ -144,4 +202,9 @@ RESOURCES.forEach(resource => {
   APIServiceProvider[resource.name] = (id, query) => new APIService(resource.name, id, resource.relations, query);
 });
 
+APIServiceProvider.onThrottle = listener => {
+  throttlingListeners.add(listener);
+  return () => throttlingListeners.delete(listener);
+};
+
 export default APIServiceProvider;