Only if the APK was built from HTML. An APK is a ZIP archive: in a WebView app the original HTML, CSS and JavaScript sit in the assets folder and can be extracted by unzipping it. A native Android app has no HTML inside — its interface is compiled code — so it cannot be converted back into HTML.
Recovering your own HTML from your APK
Lost your source but still have the APK? Copy it, rename .apk to .zip, and open it. Look in assets/ for your index.html and folders. If the builder minified or packed the files, you will get them as they were bundled. Inside an APK file shows where everything lives.
cp myapp.apk myapp.zip
unzip myapp.zip 'assets/*' -d recovered
ls recovered/assetsWhy native apps can't become HTML
Native apps are compiled to DEX bytecode and use Android UI widgets. Decompilers can show approximate Java code, but there is no HTML to recover and no automatic way to produce a website from it.
Only for apps you own
Extracting someone else's app content to reuse it is usually copyright infringement and breaks most app terms. Recover your own work, or ask the author.
Frequently asked questions
Can people extract my HTML from my APK?
Yes — anyone with the file can unzip it. Do not put secrets or private data in the HTML.