diff --git a/packages/frontend/src/components/composer/Composer.tsx b/packages/frontend/src/components/composer/Composer.tsx
index b8b5058bc..8b2acb210 100644
--- a/packages/frontend/src/components/composer/Composer.tsx
+++ b/packages/frontend/src/components/composer/Composer.tsx
@@ -248,7 +248,9 @@ const Composer = forwardRef<
 
     try {
       // Write clipboard to file then attach it to the draft
-      const path = await runtime.writeClipboardToTempFile(file.name || `file.${extension(file.type)}`)
+      const path = await runtime.writeClipboardToTempFile(
+        file.name || `file.${extension(file.type)}`
+      )
       await addFileToDraft(path, msgType)
       // delete file again after it was sucessfuly added
       await runtime.removeTempFile(path)
diff --git a/packages/target-browser/Readme.md b/packages/target-browser/Readme.md
index 6fd6c885a..23d34ac02 100644
--- a/packages/target-browser/Readme.md
+++ b/packages/target-browser/Readme.md
@@ -41,3 +41,7 @@ pnpm run start
 Then point your browser to <https://localhost:3000> and acept the locally signed certificate to continue.
 
 > If you get an "The connection was reset"-Error, then you have likely forgotten to use http**s** instead of http.
+
+### Known broken things
+
+> Image Cropper is broken because accesing tmp files directly isn't implemented. Suggestion: handle image preview in cache or memory.
diff --git a/packages/target-browser/runtime-browser/runtime.ts b/packages/target-browser/runtime-browser/runtime.ts
index 8ef778595..5b2facb3b 100644
--- a/packages/target-browser/runtime-browser/runtime.ts
+++ b/packages/target-browser/runtime-browser/runtime.ts
@@ -276,7 +276,8 @@ class BrowserRuntime implements Runtime {
     const clipboardItems = await navigator.clipboard.read()
     for (const clipboardItem of clipboardItems) {
       for (const type of clipboardItem.types) {
-        if (type === 'text/html') { /* ignores html. Needed for images copied from web */
+        if (type === 'text/html') {
+          /* ignores html. Needed for images copied from web */
           continue
         }
         const blob = await clipboardItem.getType(type)
@@ -296,14 +297,34 @@ class BrowserRuntime implements Runtime {
     }
     throw new Error('No supported clipboard item found')
   }
-  writeTempFileFromBase64(_name: string, _content: string): Promise<string> {
-    throw new Error('Method not implemented.')
-  }
-  writeTempFile(_name: string, _content: string): Promise<string> {
-    throw new Error('Method not implemented.')
+  async writeTempFileFromBase64(
+    name: string,
+    content: string
+  ): Promise<string> {
+    return (
+      await (
+        await fetch(`/backend-api/uploadTempFileB64/${name}`, {
+          method: 'POST',
+          body: content,
+        })
+      ).json()
+    ).path
+  }
+  async writeTempFile(name: string, content: string): Promise<string> {
+    return (
+      await (
+        await fetch(`/backend-api/uploadTempFile/${name}`, {
+          method: 'POST',
+          body: content,
+        })
+      ).json()
+    ).path
   }
-  removeTempFile(_name: string): Promise<void> {
-    throw new Error('Method not implemented.')
+  async removeTempFile(name: string): Promise<void> {
+    await fetch(`/backend-api/removeTempFile`, {
+      method: 'POST',
+      body: name,
+    })
   }
 
   activeNotifications: { [chatId: number]: Notification[] } = {}
@@ -520,7 +541,7 @@ class BrowserRuntime implements Runtime {
       }
       if (blob.type !== 'image/png') {
         const img = new Image()
-        const blobPromise = new Promise<Blob>((resolve, reject) => {
+        const blobPromise = new Promise<Blob>(async (resolve, reject) => {
           img.onload = async () => {
             try {
               const canvas = new OffscreenCanvas(
@@ -569,10 +590,38 @@ class BrowserRuntime implements Runtime {
     }
     return ''
   }
-  async showOpenFileDialog(
-    _options: RuntimeOpenDialogOptions
-  ): Promise<string> {
-    throw new Error('Method not implemented.')
+  async showOpenFileDialog(options: RuntimeOpenDialogOptions): Promise<string> {
+    const extstring = options.filters
+      ?.map(filter => filter.extensions)
+      .reduce((p, c) => c.concat(p))
+      .map(ext => `.${ext}`)
+      .join()
+    return new Promise(resolve => {
+      const input = document.createElement('input')
+      input.type = 'file'
+      input.accept = extstring || ''
+      input.onchange = async () => {
+        if (input.files != null) {
+          resolve(
+            (
+              await (
+                await fetch(
+                  `/backend-api/uploadTempFile/${input.files[0].name}`,
+                  {
+                    method: 'POST',
+                    body: input.files[0],
+                  }
+                )
+              ).json()
+            ).path
+          )
+        } else {
+          resolve('')
+        }
+      }
+
+      input.click()
+    })
   }
 
   openLink(link: string): void {
diff --git a/packages/target-browser/src/backendApi.ts b/packages/target-browser/src/backendApi.ts
index 05192278f..0608df69a 100644
--- a/packages/target-browser/src/backendApi.ts
+++ b/packages/target-browser/src/backendApi.ts
@@ -1,5 +1,5 @@
 import express, { json as BodyParserJson, Router } from 'express'
-import { mkdtemp, writeFile } from 'fs/promises'
+import { mkdtemp, writeFile, unlink } from 'fs/promises'
 import { basename, join } from 'path'
 import { tmpdir } from 'os'
 import {
@@ -64,7 +64,7 @@ BackendApiRoute.post(
     type: () => {
       return true /* Accept all filetypes */
     },
-    limit: '500mb'
+    limit: '500mb',
   }),
   async (req, res) => {
     try {
@@ -80,7 +80,57 @@ BackendApiRoute.post(
       console.log(tmpFile)
       console.log(filename, tmppath, filepath)
     } catch (error) {
-      res.status(500).json({message: 'Failed to create Tempfile'})
+      res.status(500).json({ message: 'Failed to create Tempfile' })
+    }
+  }
+)
+
+BackendApiRoute.post(
+  '/uploadTempFileB64/:filename',
+  express.raw({
+    type: () => {
+      return true /* Accept all filetypes */
+    },
+    limit: '500mb',
+  }),
+  async (req, res) => {
+    try {
+      const tmpFilebin: Buffer = Buffer.from(req.body.toString(), 'base64')
+
+      const filename = basename(req.params.filename)
+      const tmppath = await mkdtemp(join(tmpdir(), 'tmp-'))
+
+      const filepath = join(tmppath, filename)
+      await writeFile(filepath, tmpFilebin, 'binary')
+
+      res.status(200).send({ path: filepath })
+      console.log(tmpFilebin.toString('utf-8'))
+      console.log(filename, tmppath, filepath)
+    } catch (error) {
+      res.status(500).json({ message: 'Failed to create Tempfile' })
+    }
+  }
+)
+
+BackendApiRoute.post(
+  '/removeTempFile',
+  express.raw({
+    type: () => {
+      return true /* Accept all filetypes */
+    },
+  }),
+  async (req, _res) => {
+    try {
+      const filepath = req.body.toString('utf8')
+      console.log(filepath)
+      if (filepath.includes('tmp') && !filepath.includes('..')) {
+        await unlink(filepath)
+      }
+    } catch (e) {
+      // file doesn't exist, no permissions, etc..
+      // full list of possible errors is here
+      // http://man7.org/linux/man-pages/man2/unlink.2.html#ERRORS
+      console.log(e)
     }
   }
 )