diff --git a/cli/cli.ts b/cli/cli.ts
index c305d8b7c10..0fb5acc3dbb 100644
--- a/cli/cli.ts
+++ b/cli/cli.ts
@@ -7092,7 +7092,18 @@ ${pxt.crowdin.KEY_VARIABLE} - crowdin key
 
     advancedCommand("augmentdocs", "test markdown docs replacements", augmnetDocsAsync, "<temlate.md> <doc.md>");
 
-    advancedCommand("crowdin", "upload, download, clean, stats files to/from crowdin", pc => crowdin.execCrowdinAsync.apply(undefined, pc.args), "<cmd> <path> [output]")
+    p.defineCommand({
+        name: "crowdin",
+        advanced: true,
+        argString: "<cmd> <path> [output]",
+        help: "upload, download, clean, stats files to/from crowdin",
+        flags: {
+            test: { description: "test run, do not upload files to crowdin" }
+        }
+    }, pc => {
+        if (pc.flags.test) pxt.crowdin.setTestMode();
+        return crowdin.execCrowdinAsync.apply(undefined, pc.args)
+    })
 
     advancedCommand("hidlist", "list HID devices", hid.listAsync)
     advancedCommand("hidserial", "run HID serial forwarding", hid.serialAsync, undefined, true);
diff --git a/cli/crowdin.ts b/cli/crowdin.ts
index bfe7513a729..7e2d4255966 100644
--- a/cli/crowdin.ts
+++ b/cli/crowdin.ts
@@ -5,7 +5,7 @@ import * as path from 'path';
 import Map = pxt.Map;
 
 import * as commandParser from './commandparser';
-import { downloadFileTranslationsAsync, getFileProgressAsync, listFilesAsync, uploadFileAsync } from './crowdinApi';
+import { downloadFileTranslationsAsync, getFileProgressAsync, listFilesAsync, restoreFileBefore, uploadFileAsync } from './crowdinApi';
 
 export function uploadTargetTranslationsAsync(parsed?: commandParser.ParsedCommand) {
     const uploadDocs = parsed && !!parsed.flags["docs"];
@@ -229,6 +229,15 @@ export async function execCrowdinAsync(cmd: string, ...args: string[]): Promise<
             }
             await execDownloadAsync(args[0], args[1]);
             break;
+        case "restore":
+            if (!args[0]) {
+                throw new Error("Time missing");
+            }
+            if (args[1] !== "force" && !pxt.crowdin.testMode) {
+                throw new Error(`Refusing to run restore command without 'force' argument. Re-run as 'pxt crowdin restore <date> force' to proceed or use --test flag to test.`);
+            }
+            execRestoreFiles(args[0]);
+            break;
         default:
             throw new Error("unknown command");
     }
@@ -371,3 +380,33 @@ async function execStatsAsync(language?: string) {
         console.log(`blocks\t ${language}\t ${(translated / phrases * 100) >> 0}%\t ${(approved / phrases * 100) >> 0}%\t ${phrases}\t ${translated}\t ${approved}`)
     }
 }
+
+async function execRestoreFiles(time: string | number) {
+    let cutoffTime;
+
+    if (!isNaN(parseInt(time + ""))) {
+        cutoffTime = parseInt(time + "");
+    }
+    else {
+        cutoffTime = new Date(time).getTime();
+    }
+
+    const crowdinDir = pxt.appTarget.id;
+
+    // If this is run inside pxt-core, give results for all targets
+    const isCore = crowdinDir === "core";
+
+    const files = await listFilesAsync();
+
+    for (const file of files) {
+        pxt.debug("Processing file: " + file + "...");
+
+        // Files for core are in the top-level of the crowdin project
+        const isCoreFile = file.indexOf("/") === -1;
+
+
+        if ((isCore && !isCoreFile) || !file.startsWith(crowdinDir + "/")) continue;
+
+        await restoreFileBefore(file, cutoffTime);
+    }
+}
\ No newline at end of file
diff --git a/cli/crowdinApi.ts b/cli/crowdinApi.ts
index 293ede5191a..48547f178f0 100644
--- a/cli/crowdinApi.ts
+++ b/cli/crowdinApi.ts
@@ -299,6 +299,8 @@ async function getAllFiles() {
 }
 
 async function createFile(fileName: string, fileContent: any, directoryId?: number): Promise<void> {
+    if (pxt.crowdin.testMode) return;
+
     const { uploadStorageApi, sourceFilesApi } = getClient();
 
     // This request happens in two parts: first we upload the file to the storage API,
@@ -318,6 +320,8 @@ async function createFile(fileName: string, fileContent: any, directoryId?: numb
 }
 
 async function createDirectory(dirName: string, directoryId?: number): Promise<SourceFilesModel.Directory> {
+    if (pxt.crowdin.testMode) return undefined;
+
     const { sourceFilesApi } = getClient();
 
     const dir = await sourceFilesApi.createDirectory(projectId, {
@@ -332,14 +336,85 @@ async function createDirectory(dirName: string, directoryId?: number): Promise<S
     return dir.data;
 }
 
+export async function restoreFileBefore(filename: string, cutoffTime: number) {
+    const revisions = await listFileRevisions(filename);
+
+    let lastRevision: SourceFilesModel.FileRevision;
+    let lastRevisionBeforeCutoff: SourceFilesModel.FileRevision;
+
+    for (const rev of revisions) {
+        const time = new Date(rev.date).getTime();
+
+        if (lastRevision) {
+            if (time > new Date(lastRevision.date).getTime()) {
+                lastRevision = rev;
+            }
+        }
+        else {
+            lastRevision = rev;
+        }
+
+        if (time < cutoffTime) {
+            if (lastRevisionBeforeCutoff) {
+                if (time > new Date(lastRevisionBeforeCutoff.date).getTime()) {
+                    lastRevisionBeforeCutoff = rev;
+                }
+            }
+            else {
+                lastRevisionBeforeCutoff = rev;
+            }
+        }
+    }
+
+    if (lastRevision === lastRevisionBeforeCutoff) {
+        pxt.log(`${filename} already at most recent valid revision before ${formatTime(cutoffTime)}`);
+    }
+    else if (lastRevisionBeforeCutoff) {
+        pxt.log(`Restoring ${filename} to revision ${formatTime(new Date(lastRevisionBeforeCutoff.date).getTime())}`)
+        await restorefile(lastRevisionBeforeCutoff.fileId, lastRevisionBeforeCutoff.id);
+    }
+    else {
+        pxt.log(`No revisions found for ${filename} before ${formatTime(cutoffTime)}`);
+    }
+}
+
+function formatTime(time: number) {
+    const date = new Date(time);
+    return `${date.toLocaleDateString()} ${date.toLocaleTimeString()}`;
+}
+
+async function listFileRevisions(filename: string): Promise<SourceFilesModel.FileRevision[]> {
+    const { sourceFilesApi } = getClient();
+
+    const fileId = await getFileIdAsync(filename);
+    const revisions = await sourceFilesApi
+        .withFetchAll()
+        .listFileRevisions(projectId, fileId);
+
+    return revisions.data.map(rev => rev.data);
+}
+
 
 async function updateFile(fileId: number, fileName: string, fileContent: any): Promise<void> {
+    if (pxt.crowdin.testMode) return;
+
     const { uploadStorageApi, sourceFilesApi } = getClient();
 
     const storageResponse = await uploadStorageApi.addStorage(fileName, fileContent);
 
     await sourceFilesApi.updateOrRestoreFile(projectId, fileId, {
         storageId: storageResponse.data.id,
+        updateOption: "keep_translations"
+    });
+}
+
+async function restorefile(fileId: number, revisionId: number) {
+    if (pxt.crowdin.testMode) return;
+
+    const { sourceFilesApi } = getClient();
+
+    await sourceFilesApi.updateOrRestoreFile(projectId, fileId, {
+        revisionId
     });
 }